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Version 3.5 Quick Start Manual

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PFTrack - Product Manual 2

PFTrack v3.5 - Quick Start Manual V 1.0

Please remember that existing footage or images that you may want to include in your project may be protected under copyright law. The unauthorizedincorporation of such material into your new work could be in violation of the rights of the copyright owner. Please be sure to obtain any permissionrequired from the copyright owner.

The content of this manual is intended for informational use only, is subject to change without notice, and should not be considered as a commitment byThe Pixel Farm Ltd.The Pixel Farm Ltd assumes no responsibilty or liability for any errors or inaccuracies that may appear in the informational contentcontained in this guide.

The Pixel Farm name and Cow Logo are registrerd trademarks of The Pixel Farm Ltd. PFTrack, PFBarn, PFBarrel, PFStable, PFRetime, PFBlur and PFPlate aretrademarks ofThe Pixel Farm Ltd.Other company and product names may be trademarks or registered trademarks of others. Images from Pride are repro-duced with the kind permission of John Downer Productions

The Pixel Farm Ltd67 Bexley Street,Windsor,Berks, SL4 5BX, UK

2006 The Pixel Farm Ltd.All right s reserved

www.thepixelfarm.co.uk

[email protected]

www.thepixelfarm.co.uk

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Co n t e n t s

Introduction

Using this Manual 4

Conventions Used in This Manual 4

What is PFTrack? 4

PFTrack in Match Moving 5

PFTrack in Pre Viz 5

PFTrack in Compositing 6New in Version 3.5 6

Quick Start Manual

Installing 8

Licensing 8

Setting Preferences 9

Building a Project 10

Importing And Modifying Footage 11

Auto Track And Calibrate Footage 12Track Quality 13

Solving Multiple Camera Motion 14

Camera Translation 15

Adding User features 15

Feature Constraints 16

What Are Mattes 16

View Your Track In 3D 17

Setting The Origin 18

Orientate And Navigate 18

Object Tracking 19

Geometry Tracking 21

Motion Capture 24

Optical Flow Analysis 25

Z Depth Extraction 26

Image Based Modelling 28

Semi-automatic Lens Distortion Correction 31

Editing Camera F-Curves 32

Using Survey Data 33

Exporting Data 34

Getting Help 35


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Introduction

Using this Manu a lThis user guide is designed to enable experienced users of earlier versions of PFTrack or othermatch move applications to quickly get up and running, as well as explaining the unique fea-tures and tools within PFTrack V3.5 in some detail. It is also designed as a comprehensiveguide to those new to PFTrack, match-moving and motion analysis.

If you want to jump straight in all you need is, the Quick Start to get you up and running. Weadvise that new users work through the tutorials on our web site in order to fully understandthe power of PFTrack in the production environment.

The Reference Manual offers a comprehensive reference guide to all the tools and featureswithin PFTrack, with a detailed overview of each function. Once you are familiar with the

basics, it is here that you find how to get the most out of the software.The reference guide isorganised in logical function groups to make it easier to find your way around PFTrack.

If you run into problems we have included a trouble shooting section in the ReferenceManual. This offers advice on the most common issues with installation and a detailedoverview of the licensing process. Please consult this section before contacting our supportteam. Our web site also features an FAQ section with additional information.

Co nventions used in this Manu a lAs a rule, most functions within PFTrack are identical on all operating systems. Wherefunctions are specific to an operating system, the differences will be explained. Where screenshots are used they may appear slightly different on other operating systems. However,

unless otherwise stated, the options contained within the screen shot will be the same acrossall platforms.

Menu items are indicated as Italic text, as are options within Menus.

The word Folder is used throughout the manual and refers to a folder in Mac OSX orWindows, or a directory in Linux or IRIX.

What is PFTra ck ?Firstly its important to know what PFTrack is not. PFTrack is not merely another single pur-pose match moving application. It is much more than that. Certainly PFTrack enables

Computer Generated effects to be exactly matched with film or video sequences no matter

what their resolution. PFTrack V3.5 is also a comprehensive suite of analysis technologiesdesigned to extract both detailed camera information and pixel motion data from video and

film sequences and allow this data to be fully utilised within a post-production environment.

Where PFTrack 3.5 stands head and shoulders above the crowd is its comprehensive range of

tools and its common-sense approach to dealing with complex workflow issues and datamanagement. These include the handling of proxy image resolutions, manipulation of imagedata and batch processing of tracked shots over a cross platform network, allowing multiple

shots to be accessed and processed simultaneously. The philosophy behind data produced byPFTrack is analyse once use many times. PFTrack 3.5 allows the user to work with camera,pixel and geometrical data within a fully collaborative environment. Once the data has been

generated, it is available to provide a single reference source for multiple operations. Since


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everyone working on a project will be using the same data (from 3D animators to the 2D

compositors) consistency throughout a project is guaranteed.This delivers improved results

along with time and cost savings and removes the need for multiple clip processing. The opti-

cal flow data can be used to retime shots or produce motion blur while the camera data isused for match moving computer generated animation.

PFTrack 3.5, in conjunction with other Pixel Farm products, has been designed with first hand

knowledge of digital content production and management in film and television. It addressespractical problems of logistics and production workflow within a post facility as well as gen-erating the data required to get your job done.

P FTra ck in Match MovingPFTrack 3.5 offers users the most comprehensive suite of match moving tools in any applica-

tion, as well as providing unique ways to obtain camera and motion data from footage.PFTrack offers:

Fully automatic tracking capabilitiesAdvanced user feature trackingSingle Solve of Multiple Camera Motions

Object trackingGeometry based trackingEditable post solve camera parameters

All these features are backed up with the most robust camera solver available, giving you fastand accurate results. Unlike other match moving applications, PFTrack allows you to manipu-

late tracking data at many levels. From the simple one button click approach, right thoughtto building complex mattes and editing of individual camera parameters via spline-based F-

Curves. Hybrid, automatic and manual tracking options provide the means to get the best ofboth worlds when tracking complex sequences and 3.5 introduces the ability to solve formultiple camera motions in a single pass.

I m p ro ved geometry based tra cking functionality within PFTra ck 3.5 provides all the tools you needto import geometry and tra ck this into your sequence.This can be used for extracting motion fo r

head and face replacement or to tra ck an entire set model into a shot rather than having to match

the set position to exported camera data. Geometry can also be used to extract camera motioninstead of using fe a t u re tra ck s , giving you maximum control over the re s u lt s .

P FTra ck in Pre Vi z

PFTracks motion capture functionality, image based modelling and automated Z depthextraction are all ideal tools for use in the pre-visualisation stage of a project.The tools with-

in PFTrack have been designed to provide ways to quickly produce useful information thatcan be used as guidance when working up a project.

Animation guidance and path planning can be made a lot easier by providing both geometryand camera information to the 3D department. This can be done using the image based mod-elling and the Z Depth extraction tools.

Multiple cameras can be used to shoot a sequence and the results used to generate motioncapture data. Again allowing tests to be carried out without the need to rent an expensive

motion capture studio.


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P FTra ck in Co m p o s t i n gClearly this is not simply a single purpose match-moving application but a high-end 3D dataanalysis and production workflow toolset. Designed to produce excellent results while saving

you time and money. PFTracks optical flow tools. track individual pixels from one frame tothe next, building a comprehensive data model of all pixel movement within a shot. PFTrackhas a comprehensive toolset to modify and enhance any anomalies in the flow data, allowing

you to produce an accurate flow model.

A suite of editing tools allows you to clean up flow data before exporting the optical flowdata for use within 2D compositing application. Optical flow data can be used for Retiming,Image Stabilisation, Motion Blur and even for driving 3D particle systems

The Z Maps produced by PFTrack are ideal for use as clipping guides, depth based matting,focal effects and layer generation.

New In Ve rsion 3.5PFTrack V3.5 is the severnth major release of the application and contains over 50 new fea-tures and enhancements driven by both our research and customer requests. PFTrack V3.5includes a brand new camera solver. Faster than ever the new 3.5 solver adds three new cam-era types and allows multiple camera motions to be solved and exported in a single process.Shots can be broken down into multiple camera motions using automatic or manualkeyframes and each segment can then be assigned one of seven camera motion types.Another first in a tracking application. segmented solving means that you no longer have to

break shots down andcarry out individual solvesand try and join theresults back togetheragain. The new solver alsoallows partial solves to beused in very difficultshots. If the camera solvefails at any point, PFTrackwill still give you a partialcamera track for as muchof the shot as possible.You will no longer havethe frustration of seeing asolve get to 95% beforefailing and not giving

you anything!

After solving, the camera can be transformed using numerical edit boxes You can enter rela-tive or absolute translation, rotation and scale adjustments in the Translate, Rotate andScale edit boxes. The camera can also be transformed using the Camera Orientation toolbarbutton. This operates in a similar way to scene orientation.

A new Auto-Mesh modelling tool in 3.5.This will triangulate a set of feature points and buildan editable mesh for export to a 3D system. This can be used in conjuction with a new Viewmenu option called Missing Features. This toggles display of projection points for featuresthat aren't tracked in the current frame.This is useful for the auto-mesh image-based model-ling, where you often only want to triangulate features visible from the camera .Image-basedmodelling primitives can now also be used to provide hints for the Z-Depth calculation

greatly improving results.


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The use of survey data has been extended as points can now be specified as either Exact orApproximate. Exact points are assumed to be measured exactly. Approximate survey pointshave an associated uncertainty, so for example, you can specify that the point is approxi-mately at position (1,2,3) with an uncertainty of 0.01. This would mean the the true surveymeasurement is somewhere between 0.99 and 1.01 for the x coordinate, and similarly for the

y and z coordinates.

After feature tracking, you cansee how many frames arespanned by each feature, aswell as find out which framesdo not have enough features inthem.

Other GUI improvmentsinclude new short-cut buttons

for forward/backward user-fea-ture tracking on either side ofthe playback controls and aright-click on the Auto-Features item in the ShotOverview list opens a popupmenu for sorting the features.


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Q u i ck St a rt

Installing PFTra ckIn most cases you will receive your copy of the software as a download.The principle is thesame for a downloaded version of the software as it is for a copy provided on CD. In thisQuick Start we look at the installation on Mac and PC of a node locked license. This is themost common type of installation and ties the software to a single machine. For Linux andIRIX installations or the installation of a floating server-based license please refer to thedetailed information in the, PFLic Licensing manual.You will also need a three-button mouseto use PFTrack properly on any operating system, including Mac OS X.You may also have pur-chased a Dongle to use with your software. The Dongle needs to be plugged into the machineon which the software is installed and drivers may need to be installed on that machinebefore your are able to use the Dongle.

Mac OS XPFTrack 3.5 requires Mac OS X 10.4.7 or later. If you have an earlier version of the OS you willneed to upgrade. As a rule any hardware supporting OS X 10.4 will run PFTrack. However,because it is a highly processor intensive application we recommend a G5 or Intel Mac withat least 1GB of RAM and a graphics card with 64MB of memory. If you are processing longshots or making extensive use of the optical flow tools, we recommend at least 2GB of RAMand a graphics card with 128MB of memory. If you are using an Intel based Mac please ensure

you install the Intel version of the software.

After double clicking on the application installer you will be guided through the installationprocess. By default the installer creates a Folder called Pixel Farm in your applications

folder. You will need to have Administor rights to install the software.

Windows PCPFTrack 3.5 has been tested with Microsoft Windows XP using NVidia GeForce 2, 3, 4 and FXand 6600/6800 cards, and ATI Radeon 9700 and 9800 graphics cards. To run PFTrack onWindows youll need to have DirectX 8.1 or later installed.As with everything the better theprocessor the faster the software will run.

PFTrack for Windows comes as an executable file whether you download it from the Internetor install it from a CD. To install PFTrack, double click on the executable and follow the onscreen directions.

Licensing PFTra ckPFTrack requires a license in order to run.The license file is a simple text file that will be sentto you once you have purchased the software. Most users will be running the software on asingle machine using a Node Locked license. This type of license lives inside the Pixel Farmfolder and is locked to a particular machine. This means if you move your software to a newmachine it will not work.Your license will turn up as a text file called license.txt and all youhave to do is save this in the Pixel Farm folder and off you go. It is important not to alter theformat or name of the license file, as this will stop it working.

To obtain a license you will need your Pixel Farm Host ID.This is not the same as the MAC orEthernet address but a unique number PFTrack uses to identify your machine. In order to find

your Host ID you can simply run PFTrack after installation. An error message will be displayed


Quick Start

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containing your Host ID.You can copy and paste your Host ID from this message in order toapply for your license. If you have a Dongle installed, then the Host ID of the Dongle will bedisplayed.To check this remove the Dongle and try to run PFTrack again, you should see a dif-ferent Host ID. If not please ensure you have the correct Dongle drivers installed. Check oursupport pages for Driver download locations.

The other option is to run a license server and a floating license.The license server is a machine on your network that containsthe license and allows other machines to use this license as andwhen they need to. This has the advantage of allowing anymachine on the network to run the software. The license on thelicense server can allow any number of clients to use the soft-ware, limited to the number of licenses you have purchased.

Important Note: PFTrack Version 3.5 requires a different license than older versions. If youare upgrading you will need to obtain a new license. Details of setting up a license server can

be found in the PFLic manual.

Setting Pre fe re n c e sB e fo re we jump into your first project it is worth taking a little time to explain a couple of PFTra ck s pre fe re n c e s .As with many applications you can set pre fe rences to alter the behaviour of thea p p l i c a t i o n ,and these are explained in more detail in Pa rt 2.The most important one at this stage is setting thememory cach e .

The memory cache is important because it has a major effect on the ove rall performance of PFTra ck.The mem-ory cache sets the amount of RAM that is re s e r ved for storing frames of your fo o t a ge in memory,and as a ru l e ,the bigger the cache the better the perfo r m a n c e .The size of the cache you set will depend on how mu ch RAM

you have installed, the re solution of the fo o t a ge you are tra cking and the memory re q u i rements of the opera t-

ing system you are ru n n i n g. N o t e :Mac OS X can curre n t ly only address 2GB of Ram per application.

To ch a n ge the cache pre fe rences Select P re fe rences f rom the file menu (note that on Mac OS X machines thep re fe rences option appears under the P FTra ck m e nu ).A tabbed Pre fe rences dialog box will appear.C l i ck on the

Pe r formance tab.You can then set the amount of memory used by the cache in mega by t e s .The screen shotshows a memory cache set to 700MB.The C a che on import option allows PFTra ck to automatically cach e

your clip into RAM when it is first loaded from disk.This does slow down the import process but then speeds upworking once the shot is loaded up.You will also see an option to set the number of threads (or processes) usedby PFTra ck for tra cking and optical flow calculations. By defa u lt, this is set to the number of pro c e s so rs ava i l a b l eon your system.If you have a dual pro c e s sor machine and wish to re s t rict PFTra ck to a run on a single pro c e s so r,

you can do so by setting the number of threads to one. It is worth noting that when fe a t u re tra ck i n g,e x t raactivities performed by the operating system may mean that using two theads is not exactly twices as fast asone using one tre a d .


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Two other pre fe rences worth setting at this point are Load locked proj e c t and Auto Save in the G e n e ral tab,a sthese can save you time and fru s t ration if you do have pro b l e m s .C l i cking the OS Native b ox under Import inthe Interface tab will gi ve Mac and Windows users a standard OS file browser to load fo o t a ge .You may alsowant to ch a n ge the number of undo leve l s ,as a ge n e ral rule the more you have , the more RAM you will needto set aside

The Keys tab provides access to all the key b o a rd shortcuts in PFTra ck.You can quick ly ch a n ge these by editingthe values shown in the second column.When entering modifier keys such as Co n t ro l orS h i f t make sure yo utype the modifier name corre c t ly,so Shift+C would be entered as S h i f t + C.

You can quick ly re s t o re PFTra ck to its defa u lt settings across all tabs by clicking the D e fa u lt button at the bot-tom of the Pre fe rence window.

Building a Proj e c tWhen you first open up the application you will find a blank interface, like the one shownhere.The interface is split into five main areas. An icon tool bar, area 1, runs across the top ofthe screen giving you access to the most common operations in PFTrack. Area 2 shows theproject information, Area 3 shows Shot information, Area 4 displays the footage and Area 5shows the time-line, dope sheet, f-curves and playback options and also contains details ofthe cache and provides user feedback via the log window.

The first thing to do is create a New Project. A Project is the container holding all the shotsyou are working on and a Project can contain any number of shots. To create a new project,select File>New Project.You are then shown the new project dialog in which you can set thelocation of the new project and its name. If you are returning to a project created earlier clickthe Open Project button shown left and navigate to its location to load it.

P FTra ck projects are spilt into a number of files within the dire c t o r y.


Quick Start

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3

4

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Open Projectbutton

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The .ptp file is the main file holding all the links to the va rious shots, and each shot is stored in its ownd i re c t o r y.If items are moved within the project dire c t o r y, you may need to manu a l ly locate them nexttime you open the proj e c t. H o w e ve r,we recommend that you do not manu a l ly edit the project dire c t o r yas this can mean the project has no longer load corre c t ly.Once a project is save d , P FTra ck can automatical-ly open the last project you were working on, a lthough this behaviour can be turned on/ off in the pre fe r-e n c e s .Once you have set up your project you will need to import some fo o t a ge to tra ck.

I m p o rting and Modifying Fo o t a geTo import your footage into PFTrack select File> Import Footage, click the Import Footagebutton or press Cmd/Ctrl+I. Navigate to the footage you need. Click on your chosensequence and then click Load. Full details of supported file formats can be found in Part 2 ofthis manual.

The first frame will now appear in the main image window and the footage will appear high-lighted in the shot overview panel.You can play the sequence through by using the playbackbuttons at the bottom of the screen or pressing the Space Bar on your keyboard. At first play-back may seem slow if you arent using the cache, or if PFTrack is reading data off disk and-caching the footage into memory.

To make sure of the basic information about your footage and ensure you will be viewing itcorrectly you can check the Footage Format. To do this right-click on the name of thefootage (in the shot overview panel) and select Edit Format to reveal options in the pop-upbox. This allows you to change the default playback rate or de-interlace the footage.

Similarly if you want to make any changes to the appear-ance of your footage, such as altering contrast, brightness orsaturation in order to obtain a better track, you can right-click on its name and select Manipulate to reveal manipula-

tion options in the pop-up window. This process is non-destructive and can be reset at any point. It does howeverallow you to manipulate footage without the need to haveplates re-rendered to get a better basis from which to track.

You will also notice you are able to set a proxy resolution at this stage by selecting the Proxyoption when right clicking on footage. PFTrack is able to generate proxy resolution images on-the-fly allowing you to better manage your projects when working at 2K and above.To set aproxy simply select the required resolution from the pop out menu. If you have problemstracking you can switch to a higher resolution at any time.

There are two basic types of shot you will be working with, Free Motion

and Rotation Only. If you dont know what these are, a Rotation Only ashot is where the camera is mounted on a tripod and doesnt undergo anytranslation, but does have rotations. A Free Motion camera is one that isfree to move (often hand-held) and so does undergo translations and rota-tions. PFTrack 3.5 has 4 main motion types with 7 camera motion types inall. (The other three are refinements of the main motions). The software isable to solve multiple motion types within a shot in a single solve. To usethis feature the camera must be set to Free Motion.

Make sure that you set the correct motion type in the camera parameters dialog.To do this,select Camera>Camera Parameters. From the Motion drop down menu select the type ofshot you are working with. Stationary and Motion Capture are covered in detail later.


Quick Start

Import Footagebutton

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N o t e that even if your camera is translating very slightly, but the rest of your scene is very far from the cam-e ra , you may still have to select the Rotation O n ly setting to get a good quality calibra t i o n .This is becauset h e re may not be enough parallax in your fo o t a ge to acc u ra t e ly determine 3D fe a t u re positions.

The other main setting to consider at this point is the focal length. If you are lucky and havea camera data sheet for the shoot you can enter the relevant data into the CameraParameters window. If however, as is more often the case, you do not, the main considerationis the focal length type. PFTrack can estimate the focal length value itself but you must tell itif the shot has a constant or varying focal length, in short does the shot contain a zoom? Ifso then the focal length is varying and it is important that this information is provided.

Auto Tra ck And C a l i b rate Fo o t a geB e fo re you tra ck a shot you should first make sure any board e rs , t i m e-code orf rame edges are masked out. P FTra ck allows this to be done very quick ly and sim-p ly by adjusting the frame boundary.You will notice a white line around the edge

of the displayed fra m e . C l i ck on any edge of this line with the left mouse buttonand drag it in to mask out any unwanted edge details.Once this is done, you cannow go ahead and tra ck your first shot.

U n d e rs t a n d a b ly the complex calculations PFTra ck undertakes cannot always re so l ve themselves andm ay re q u i re some user interve n t i o n .At this point there fo re , and with all due dilige n c e , you should doone of these three things: either select Tra ck i n g > Tra ck and C a l i b ra t e ,hit the button (shown left) orchoose Ctrl F6 (On the Mac this is Cmd F6, you may also have to select the menu with your mousethe first time you use the key b o a rd shortcut ).

P FTra ck now begins the complex job of analysing the fo o t a ge to identify and tra ck a number of pointsor fe a t u res and then uses this information to work out the camera para m e t e rs and produce an acc u-rate 3D point cloud for the shot, along with an animated camera path.

The time this takes depends upon the length of yo u rs e q u e n c e , the complexity of the camera motion andthe speed of your mach i n e .As this happens you willsee the fe a t u res being tra cked frame by fra m et h roughout your sequence.The green ones indicate agood tra ck, the red are not so go o d .A prog ress win-dow will be displayed wh e re you can follow thep rog ress of your shot. If you have nerdy tendencies,hide the prog ress dialog and press the log button atthe bottom left of the window, and your screen willbe filled with scrolling text with all you want to know about what is going on. S i m p ly click the log but-

ton again if you want to re m o ve this window of info r m a t i o n .

The new camera so l ver re q u i res 6 or more fe a t u res to be tra cked between each frame but will ofc o u rse function better with more fe a t u res and gi ve more acc u rate re s u lt s .The 3.5 so l ver window hasc o n t rols for 6 components:

Specifying wh i ch motion group to so l veSetting Automatic or Manual key - f ra m i n gSpecifying a slower, but more acc u rate Single Frame St e p m o d eStopping the so l ver after it has built the initial so l u t i o n .Including user and/or auto fe a t u res in the so l ve .


Quick Start

Track&Calibratebutton

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P ressing St a rt or hitting the so l ve button, will so l ve the camera using the defa u lt settings.The so l ve rcan operate in automatic or manual key f rame modes.The key f rames are used to create an initial esti-mate for the camera path for part of the shot. Key f rames indicate wh e re PFTra ck thinks cameramotion ch a n ges from one type to another. Because of this you may find no key f rames are added at allif a single motion type is detected. P FTra ck will choose the best location for these key f rames when in

Au t o m a t i cm o d e , but for complex shots,these key f rames may not be sufficient tobuild a good quality initial estimate andm ay need to be placed manu a l ly.

To view any key f rames after the camera has so l ve d , c l i ck the D o p e-S button under the main vieww i n d o w.This will open the Dope Sheet in the time line area and diplay any key f rames as ora n ge bars . I fthe so l ve has fa i l e d , you can place 1, 2 or 3 key f rames manu a l ly.Try to place them in positions wh e re

you can see significant camera motion and parallax in the shot. If you place 1 key f ra m e , P FTra ck willa u t o m a t i c a l ly choose 2 more on either side. If you place 2 key f ra m e s , P FTra ck will automatically pick at h i rd .To re m o ve any key f ra m e , s i m p ly dra g -select a set of frames in the timeline and press the D e l e t e

k ey. (not the back s p a c e )

If the camera so l ve fails at any point, P FTra ck 3.5 will still gi ve you a partial camera tra ck for as mu chof the shot as possible.This is very useful on complex shots as it often saves the need to manu l ly tra ckan entire sequence.A tip here is to extend the shot by using handles at end end of the sequence.

Tra cking Q u a l i t yWhen the tra ck and calibration process is completed you will see that your fo o t a ge has returned tothe frame from wh i ch you start e d , but is now cove red with green and red dots.The green ones shouldmake up the majority as these re p resent those 3D fe a t u res wh i ch match their tra ck position well.T h ered dots show a poor 3D point.You can see exactly how poor by switching on the P rojection Erro rsoption in the Vi ew m e nu .This will draw a small line from the 3D fe a t u re point to the corre s p o n d i n g

2D tra ck point.You can also click on the Tra ck- Q button under the main view window this will displaythe tra cking quality as a graph on a per frame basis.White dots indicate wh e re a fe a t u re wa s ntt ra cked into that frame but is used in the so l ve .

After fe a t u re tra ck i n g, you can see howm a ny frames are spanned by each fe a t u re ,as well as find out wh i ch frames do noth ave enough fe a t u res in them.C l i ck the

Tra ck- L button next to the F- C u r ve and Dope-Sheet buttons. Frames are shown in red when they havefewer than 6 fe a t u res in them.As fe a t u res are tra ck e d , t h ey will appear in the display, showing wh i chf rames have been tra cked and the tra ck quality for that fra m e .This provides a means to quick ly identi-fy frames that re q u i re User Fe a t u re s adding to help get a good so l ve .

You can click on the 3D view icon to view the point cloud and camera path in 3D and nav i gate aro u n dthe scene using the mouse buttons. It is also possible to carry out the tra cking process and calibra t i n gp rocess as separate opera t i o n s .This is your second step if the combined process doesnt gi ve you there s u lts you need, and can be useful when you want to clean up your fe a t u re tra cks befo re calibra t i o n .To carry out the steps as separate processes first select the Tra ck b u t t o n .Once you tra ck is complete

you can use the Clean tra ck s option from the Tra ck i n g m e nu to re m o ve any poor tra cked points.Yo ucan then select the S o l ve button to carry out a so l ve .


Part 01 - Quick Start

New Viewerbutton

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Solving Multiple C a m e ra MotionsPFTrack 3.5s new camera solver lets you partition a shot into different segments, and specifya different type of camera motion for each segment. This should be done before solving, but

only if you are having problems with the standard solver.This compound or segmented solvecan then be exported as a single camera.

To use the segmented solver, the main Camera Motion must be set to Free Motion in theCamera Parameters window.Open the Dope-Sheet and use the CutFrame button to placecut-frames at the points where the motion of the camera changes. These will be shown asblue indicators in the Dope-Sheet. As an example, assume the camera performs the followingmotions:

Frames 1-49: Rotation OnlyFrames 50-70: Free Motion (translation and rotation)Frames 71-99: Rotation Only

In this case, you would place 2 cut-frames: one at frame 50, and another atframe 70.The cut-frame at frame 49

signifies that the motion type changes between frames 50 and 51 (the blue indicator in theDope-Sheet is actually drawn half-way between frames 49 and 50).

From the Camera menu select the Motion option and youshould see 3 segments listed: frames 1-49, frames 50-69 andframes 70-99, and alongside is a menu where you can changethe motion type for each segment. In this example, you wouldset Rotation Only for the first and last segments, andTranslation + Rotation for the middle segment.

The six different types of motion are:

Translation + Rotation:

Formally known as Free MotionTranslation Only:

Camera motion with no rotationLinear Translation:

Straight line camera motion, a dolly shot could produce this motionRotation Only:

Pan, tilt and zoom with no translation

Rotation + Small Translation:Useful for shots where the camera is not moving far, relative to the distance from the set.Interpolate:

Will initially ignore the segment during the camera solve, and then interpolate the cameramotion after the solve has completed.

After the solve has finished, you can use the camera transform tools to adjust the position ofthe camera inside each segment if this is required.


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C a m e ra Tra n s l a t i o nAfter solving, the camera can be transformedusing numerical edit boxes by selecting Transform

Camera from the Camera menu.This shows thecamera position and orientation for the currentframe.You can enter relative or absolute transla-tion, rotation and scale adjustments in theTranslate, Rotate and Scale edit boxes. Aftertyping a value, press Apply to apply the trans-form.You can change whether you want to move the current frame only, the current segmentonly, or the entire camera path by changing the Mode box.The Copy and Paste buttons canbe used to take a copy of the current camera position and then paste that into a new frame.

The camera can also be transformed using the Camera Orientation toolbar button.This oper-ates in a similar way to scene orientation. Press the Camera Orientation button and then usethe left/middle/right mouse buttons in a viewer window to transform the camera around itscurrent position. By changing the Mode in the camera transform window, the adjustmentscan be made to the current frame, the current segment or the entire shot.

Adding User Fe a t u re sWhile using automatic tracking will usually get you the results you need, the tracking pointsare positioned by the software and so they may not be exactly where you want them to helpwith compositing jobs. For example if you want to track a specific component within a shot,say - a door or window, you may want points in each corner. PFTrack cant know what youare thinking and so may not place features specifically where you need them.

PFTrack allows you to add your own points and track these through a sequence along with, orinstead of automatic points. User features can also be used to aid or influence automatictracking if youve got a really difficult shot.

To create a user feature select Tracking>New User Feature or press theUser Feature button on the toolbar. To place the user feature simply left-click at the point on the image you want. To help you place the featurewith greater accuracy, hold Shift along with the left mouse button tomagnify the location you have selected (right) and place your feature byreleasing the mouse button.The magnified window will also close.

Once youve created a new user feature, it will be selected in the shot overview window.While selected, each click in the image window will change its position. If you want to createanother user feature, either select New User Feature again from the Tracking menu, or click

on another item in the shot window, such as the User Features container, to de-select theuser features. Repeat this process to place as many user features as you need.You can alter

the region of influence used by clicking on the square box surround-ing the feature point and dragging the mouse to make it larger orsmaller.This changes the size of the region of pixels PFTrack looks atwhen tracking to determine the movement of the feature.

Right clicking on a user feature reveals a menu of further options.Choosing Track Forwards will start the tracking process for that userfeature moving forwards from the current frame. There is also an

option to Track Backwards if you did not place the user feature on the first frame. There arenew short-cut buttons for forward/backward user-feature tracking on either side of the play-


Quick Start

New User Featurebutton

Camera Orientationbutton

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back controls. Pressing these buttons willtrack all selected user-features.To track

all your user features at the same time, go into Selection Mode by clicking the toolbar iconand lassoo them, or select them in the shot overview by pressing Shift to select multiple fea-tures at the same time.

If youve already calibrated the shot, you can select Solve from these options, after trackingthe user feature. This will calculate the 3D position of the feature and place it in the scene.Selecting the Tracking Guides option allows user-features to influence the auto trackingprocess by providing hints about how the objects in the scene are moving.

Once calibrated, user features can be tagged for export. In the case of our door we could usethis to export just the four corner points to a 3D or 2D application. It is also useful to renamethe feature tracks in the shot window to make it easier to identify them. To do this, right clickon the feature and choose Rename, or double click on the feature in the project window.Once you have renamed the feature, hit the Return key to confirm the change.

While user features can be used on their own to calibrate the camera motion, you will alwaysneed at least 6 features for a Free Motion camera, or 4 for a Nodal Pan. Generally, the morefeatures you have the better provided they are tracked accurately - more poorly tracked fea-tures will have a detrimental effect on the solution.As a rule of thumb, it is much better toemploy user features along with auto features (rather than by themselves) unless you aresolving a shot with widely spaced frames. They are also useful if you do require specific track-ing points, or if the calibration is not accurate enough when using auto features alone.

Fe a t u re Co n s t ra i n t sBoth user and auto-features can be set to either Hard or Soft constraints for the solver. AHard Constraint means that the feature track is assumed to be accurate. Soft Constraint

means that the track may have errors in it. Because of this, parts of the track may be incor-rectly discarded during the camera solve. By default, auto-features are set to Soft Constraint,and user-features are set to Hard Constraint.You can change these by right-clicking on a fea-ture and changing the menu option. If your camera track is drifting in places, and you can seea particular auto-feature moving out of place, try switching that auto-feature to HardConstraint and solving for camera motion again by hitting the Re-solve Scene button. Thiswill try to ensure the camerapath matches that feature more accurately throughout the shot.

What are Mattes?PFTrack picks the features it thinks are best to achieve a good track when in automatic mode.But if your shot contains moving objects, these features may not be ideally placed, particular-ly if your footage contains large objects such as, trees or people that move independently of

the camera.You may be able to easily distinguish between these objects, but the computeroften needs some guidance.

The way to fix this is to mask out problem areas with a matte. PFTrack has a verycomprehensive set of matte tools to build and animate highly complex mattes. Mattes canalso be set up to track a moving object, or key framed to change shape to match problemareas.

To build a matte select Tracking>New Matte or click the Matte button in the toolbar andthen left click over the area up want to hide. With each click a point is added to the matte.These points can be edited once your basic shape is created. Right clicking closes the matte.Dont worry about being too accurate with the placement of the points - often a quick


Quick Start

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Setting The O ri gi nIt is unlikely the ground plan will match the position or orientation of your shot when it isautomatically placed by PFTrack. It is important that you spend some time orientating the

ground plane, as this provides the point cloud the X,Y and Z coordinates that will be usedwhen exporting to another application.While it is possible to orientate the scene within a 3Dsystems, it is possible to re-orientate data in PFTrack, a little time spent now will save a greatdeal down the road.The ground plane is also used when carrying out image based modellingwithin PFTrack so poor positioning can result in difficulty building models.

By default you should be in Navigation Mode. If for any reason this is not the case, simplyclick on the Navigation Mode button shown here.

Now you need to decide upon a suitable location for your point of origin.This is a pointaround which you will move the ground plane and it can be anywhere in your scene.You canchange the origin using a calibrated tracking point and it makes sense to select a locationwhich will be of the most practical use for the purposes of your footage, e.g. a spot on anobvious ground plane if your footage has, one which will provide a good reference within thedata for export to your 3D package.

While in Navigation Mode, find a well calibrated feature (a green dot) and move the mousepointer over this dot/feature.Youll see that the dot expands slightly and information aboutthe point appears. Now right click and from the pop-up menu select Set As Origin. Youll seethat the mesh ground plane now snaps to this selected point. This is now your point of originand PFTrack has switched to Scene Orientation Mode as indicated by the Scene Orientationbutton shown here, and now darkened.

O rientate And Nav i ga t e

In Scene Orientation Modeyou can now reposition the ground plane until it is arranged tomatch real world orientation. It is often easiest to do this in the footage window, and thebest tool for this is your eye. Use the left mouse button to rotate the ground plane aroundthe origin so it looks correct. If you need to change the origin point to a better position youcan do this at any time by selecting a new origin point, as described above.

Use the mouse to orientate as follows:

Left button = rotateMiddle button/wheel = zoom/scaleRight button = pan

To give you more precise control over adjustments to the mesh plane you can constrain the

ground planes rotation about an individual axis using the left mouse button in conjunctionwith the X, Y and Z modifer keys.You can also use the Horizon Line option in the View menu

to switch on a virtual horizon line that can help line upyour ground plane.

As you do this you will see in the 3D viewer the cam-era and point cloud move according to your adjust-ments, while the ground plane remains stationary. If

you need to quickly switch into Navigation modewhen doing this, you can use the keyboard shortcut(the N key, by default). Creating new orthographicviews can also help orientate your scene.


Quick Start

Navigation Modebutton

Orientation Modebutton

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Click the New Viewerbutton to open a new 3D window, then use the drop down menu toswitch between perspective and orthographic views. Clicking the Tile Window button willtidy your windows up.

Once you are satisfied with the position, orientation and scaling of the ground plane andsubsequent display of the 3D camera data, you may wish to check your sequence by playingit back before you export it.

Now that you have completed the track and calibration of yourfootage, examined the 3D camera data and are satisfied with theresults youve seen played back, you can export the data to the 3Dapplication of your choice.You can do this by Right-Clicking onone of the Exports items in the shot window, and selecting Newfrom the pop up menu. This allows you to choose the format ofthe export, and the file location where the data will be written.

Object Tra ck i n gPFTrack 3.0 introduced the concept of motion groups. These are individual sets of motiondata. In essence you are now able to determine a number of distinct motions within asequence and solve these independently. For example you can solve the general cameramotion as well as the motion of a rigid object moving independently from the camera, suchas a car driving along a road. Object motions can then be exported individually or as groupsto your 3D environments. In the example of tracking a car we would first use the default set-tings for tracking to obtain the camera motion.

The best way to achieve good results is to matte out theobject you wish to extract the motion from before track-ing to obtain the camera motion. After building a basic

matte over the object, Track and Solve the sequence inthe normal way. It is a good idea to leave the matte loosearound the object as matting too close to an object edge reduces the amount of informationPFTrack has to work with. The edges of a car for example are valid track points and a closecropped matte can obscure these edges making the car harder to track.This is shown in theimage above, with the more effective matte for tracking on the right. By adding a user fea-ture onto the object you are tracking and tracking it throughout the sequence you are able toattach the matte to that user feature, automatically tracking the matte over your object.Thiscan save a great deal of time when because it reduces the need to keyframe your mattethrough the entire shot.

We now have to create a motion group that will contain the

motion of the car.To do this we first open the Groups optionfrom the Tracking menu. Within this window we can build up anynumber of distinct motions. The default number of motions is setto 1 (i.e only camera motion). To add a second motion type 2into the number of motions box and then hit the New button tocreate a new group.A new motion group will be created and youcan rename this by clicking on Unnamed. In this case it is

renamed to Car. A new Motion group is also created in the project window,as shown on the right, with all the same elements as the default 'Scene'motion group.To assign a different motion to this group, right-click on thegroup name and choose Motion 1 from the popup menu.


Quick Start

New Viewerbutton

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To obtain just the motion of the car, invert the matte to matte the main area of thesequence. This is done by right clicking on the matte and selecting Invert from the pop upmenu. By default, features are tracked into the Scene motion group so in order to track intothe Car group open up the Tracking Parameters window under the Tracking menu and setthe target group to Car (or whatever you've called your second motion group).

We can then track features using the Track button to place 2D feature tracks on the object. Ifyou have used a user feature to track your matte you can set this up as a tracking guide byRight Clicking on the feature and selecting Tracking Guide from the pop up menu.You may

need to alter the number of auto features in the Tracking Parameters dialogue if you are try-ing to track a relatively small object, as the default number of 150 may confuse the camerasolver. Alternatively, you can select the Area Feature Limit option which will automaticallylimit the number of auto features that are selected according to the area of the image youare tracking into.

Once the track is complete we can solve the motion intothe new group either by Right Clicking on the group nameand selecting Solve from the popup menu, or by highlight-ing the group name and clicking the Solve button in thetoolbar.You may need to alter the number of auto featuresin the Tracking Parameters dialogue if you are trying to tracka relatively small object, as the default number of 150 mayconfuse the camera solver.

You can orientate the scene based on the camera motionas you would with a standard track, but you will alsonotice when viewed in the 3D window your object trackappears with a bounding box.This box represents theobject orientation and can be used to orientate the objectgroup independently of the main camera group. To do thisselect the group name and click the Scene Orientationbutton on the toolbar. As with ground plane orientationthe X, Y and Z keys can be used to constrain the axisaround which you move the bounding box.


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If not already selected, you can select the Model in the projectwindow by opening the Tracking Geometry container. Whenselected your model will turn yellow.You can then use themouse buttons to rotate, scale and move the model until itmatches up with the element in one frame of the footage youwant to track. Try and find a frame in the sequence that allows

you to best align the camera with the model.You will notice that a key-frame is created inthe dope sheet once you have placed your model. Alternatively you can activate manipula-tors by selecting, translate, rotate or scale from the drop down menu shown on the left.

Hit the Track Forward (or Backwards) button or and you should see the geometry startto track through your shot. Once completed the sequence will return to the frame you start-ed tracking at.You can also reverse your track direction to complete the sequence from thekeyframe you started at.

If you see the geometry start to drift from the image underneath then you can go to thatframe and using the mouse re-position the geometry to better match the footage.Again akey frame is placed in the time-line. This can be repeated as needed. Hitting the track buttonwill then re-track between key-frames blending the motion of the object appropriately.

If you have a very difficult sequence totrack you can click the S button andthis will force PFTrack to track forwardor backward one frame at a time. Each

time you hit the track button it willtrack to the next frame.You can finetune your model position and track tothe next frame. In this way even themost difficult shot can be tracked rela-tively quickly.

If you want to set the position of amodel very accurately in a frame, aswould be the case with a head or facereplacement you can attach a vertex

on your model to a pixel in the sequence. This process will try to lock your model position sothe vertex matches the pixel you have attached it to. To activate this mode select Drag fromthe object drop down.You will notice as youmove the mouse over the model a vertex underthe mouse will have a red circle around it. Onceactive you can position the vertex over the pixel

you require. Repeating this with a number ofpoints will transform the mesh to try andmatch all the pixel positions you have set. Atany point you can delete a pixel constraint byhovering the mouse over the vertex and press-ing the Delete key.


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Changing the Field Of View FOV may also help you match your imported geometry to thefootage. If you are finding it hard to position your model try altering the FOV using the upand down arrows until you find a match.

You can select a number of display modes for the imported geometry to suit your workingmethod. Hidden line is often the most useful when placingan object over a sequence especially if you are using theDrag option to position a vertex.The other modes, Facet,Smooth and Transparent can be switched using the objectview drop down menu and are shown to the left.

As well as its use for head/face replacement, geometry based tracking can be used to quicklysolve camera motion using simple geometry. For example if you are trying to track a shot inwhich you know you have right angles, you can import a cube and use this as the basis for

your solve. Even a simple plane can be used placed on a flat surface. In this case a cube wasimported and aligned with the corner of

the building. The mouse buttons and fieldof view control can then be used tomanipulate the object, for example, toline the cube up with the corner of thebuilding.

By default PFTrack will produce a staticobject and moving camera. As arule whendoing head replacment or object tracking

you will want a moving object and staticcamera.The quickest way to do this is tocreate a new motion group for the head

motion. Select Groups.. from the tracking menu and hit New to build a new motion group.You also need to set the number of motions to 2 and change the motion type for your newgroup to Motion 1 rather than the default Camera.

Select the new Motion Group in the ShotOverview and then import your geometery.The tracking geometry should appear underthe new motion group.You then follow thesame process to place the geometry and trackit over your footage. Once complete you willhave the camera motion in the Scene motiongroup and your head movement in the newmotion group.You can choose to export eitheror both of these when you export to a 3D sys-tem.You can opt to export the animatedgeometry as well as the camera motion.

You will also notice the geometry appearswith a bounding box. This box represents the geometry orientation and can be used to orien-tate the geometry independently of the main camera group. To do this select the group nameand click the Scene Orientation button on the toolbar.As with ground plane orientation theX, Y and Z keys can be used to constrain the axis around which you move the bounding box.

PFTrack 3.5 does not support the import of animated geometry however multiple geometricelements can be imported and placed within a sequence to solve highly complex movement.


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Motion C a p t u reMotion capture is the process of extracting movement information from a live action eventsuch as a person running or dancing. It is commonly used in game and film production and

applied to animated characters to give realistic animation. Motion capture can also be usedto capture subtle movement such as those of a face when talking.

PFTrack offers users the ability to undertake motion capture by combining two or more cam-era views of the same event, and tracking user features within each sequence. An example ofthis would be to set up two or three cameras pointed at an actors face.The main camera orprinciple camera would be the view you were going to use in post production, perhaps thefront view.The second and third cameras could then be set up to provide right and left handviews.

Tracking markers could then be placed on the face of an actor and the sequence filmed.Themore markers placed on the face the better the resulting track. Once you have your threevideo sequences they can be imported into PFTrack and synchronised.

After setting up a new project the first thing you need to do is import your footage. In thiscase it will be your two or three camera views. Whichever clip you have designated as theprimary footage should be imported first. Import your footage in the normal way. Either clickon the Import Footage button or select File>Import Footage.

When your primary footage is loaded you need to setup PFTracks motion capture facilities.To do this openthe Camera Parameters dialog by selectingCamera>Camera Parameters. From the Motiondrop down menu option, select Motion Capture asshown in the screen shot on the right.

Once you have done this you will notice that theImport Footage button has become active again,allowing you to import your next sequence. Repeatthe steps you took to import the first sequence andthen import a third sequence if you have one.

PFTrack will solve motion using only two cameras but in the case a facial or head tracking itis worth using three for increased accuracy. Support for multiple resolution means you canmix DV cameras for reference with a high res or film camera for the principle footage, provid-ing a fast and cheap way to produce motion capture data.

To display the additional footage, click on the New Window button, to create a second win-

dow. Click inside this window to make it active and then click on the sequence name (in theshot overview) you want the window to display. For additional sequences, repeat this process,until you have as many windows open as you need, each with a different sequence displayed.Click the Tile Window Layout button if you need to make them fit better.

The next stage is to synchronise the sequences.This is the process of making sure eachsequence is displaying exactly the same frame at each time step. To do this, find a frame ineach sequence where a clearly identifiable action is happening (something like a blink, if

youre shooting a talking head). Once you have done this, find the relevant frame in yourprimary sequence and hit the Set Sync button (right hand side of the time-line).You willnotice a blue marker is placed on the time line at that frame.


Quick Start

Import Footagebutton

New Windowbutton

TileWindowbutton

Set Syncbutton

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Next, activate your other sequences by clicking in their windows and find the correspondingframe for each, making sure to repeat the Set Sync process.When youve done this, click onthe Sync button (next to the Set Sync button) and you should find when you play through

your shot, all the sequences are synchronised, and play back together.

The next stage is the process of matching up tracking points in each sequence. The only wayto do this is by hand, placing User Features on each tracking marker.This is where your great

idea of having 1000 markers on someonesface backfires! PFTrack will performmotion capture even if you only have asingle marker on your object, althoughobviously you should place enough toensure you capture all the animation youneed. For accurate results, we generallyrecommend using at least 5 or 6 markersplaced on key points to allow you to

match them with any geometry you buildin your 3D application

Place the first user feature on a tracking marker in the primary sequence. Assuming you are inframe one, Right-Click the user feature and track forwards. Once you are happy with itsplacement click on the secondary sequence and place the same user feature on the corre-sponding tracking marker. Repeat this in the third sequence and so on, and then repeat theentire process for your other tracking markers.

Once you have user features on each marker you need to cali-brate the shot by selecting Solve Camera from the Cameramenu or pressing the toolbar button.Once the calibration is fin-

ished, you can view the 3D point cloud in the 3D window beforeexporting.

While this process can be time consuming it is the perfect toolto produce highly accurate and complex motion information. Tolearn more about the Motion Capture tools including how tospecify rigid motion constraints consult the reference manual.

Optical Flow A n a ly s i sThe advanced optical flow tools in PFTrack 3.5 work alongside the already powerful trackingtoolset and provide incredibly detailed per-pixel motion analysis of your footage.

Optical flow tracks pixels from one frame to the next, building a comprehensive data modelof all pixel movement. A simple brush based tool set allows you to modify and enhance anyanomalies in the flow data, producing an accurate flow field. A number of viewing methodsalso provide the means to fully check the data prior to export. Any PhotoShop user will soonget to grips with these tools. The Pixel Farm provide a number of plug-ins for major com-positing applications that use the optical flow data to perform common tasks such as re-tim-ing and per-pixel motion blur (PFRetime and PFBlur).Alternatively, the data can also bepassed to other 3rd party compositing applications by exporting the flow data as RGB orfloating-point images.

The optical flow tools calculate a flow vector for every pixel, and use feature tracks as hintsto help out the calculation. Before calculating a flow field, you must therefore track someuser or auto-features. If you want, you can also calibrate the shot before calculating flow.This


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can be performed on a single task by hitting the Track and Flow button or can be carried outafter you have solved your shot by using the Calculate Flow button.

It is important to have a good spread of features throughout your shot to make sure you getan accurate flow field. If you have any moving objects in your scene, it would be wise tomake sure that a user feature or two is tracked on each one.

To prepare the optical flow calculation, select Optical Flow>Parameters The optical flowwindow (pictured right) will then appear. The options within this window are fully explainedin the reference manual but for now just select the correct camera motion, and pressCalculate Flow.

As the flow calculation progresses you will see a coloured overlay appear on the screen. Thisis a representation of the flow accuracy of each pixel. As with camera tracking, red areas indi-cate areas where the analysis could not be performed accurately.

Once the sequence has finished you canzoom into the flow field and see eachindividual pixels motion vector.Thearrows indicate the direction and dis-tance that each pixel moves, and arecoloured simiary to the coloured overlay.If you need to clean up any areas, selectthe Edit option from the Optical Flowmenu.

You can use these tools to fix any prob-lem areas by painting on motion vectors

or cloning them from other areas. If you are going to be using the optical flow data for retim-ing, one very useful feature within the Parameters dialogue is the Morphed Frame option inthe Display drop down menu.This generates a mid-frame between the current displayedframe and the next giving you a fast visual reference showing any problem area with yourflow data. If this frame appears OK then when you retime your shot you should get goodresults.

Z Depth Extra c t i o nPer-pixel Z depth information from a moving sequence can now be derived within PFTrack.This produces a grey map that can be used within a compositing system for a number ofdepth based effects and can also be exported as a 3D mesh, for import into common 3Dmodelling applications.

To build a Z map the first stage is to track and solve your shot. The depth map calculationsuse solved feature positions as hints, so once you have solved for camera motion and featurepositions, you can press the Depth Map button or chooseCamera>Depth Map to open the depth parameter window. Mostof the settings have been set for optimum performance so inmost cases can be left at their default values. We will explain thesettings here, so if you do not get the results expected you canadjust things and recalculate.

The Look Ahead parameter sets the number of frames PFTracklooks ahead of your current frame in order to do pixel positioncomparison. This comparison is used to calculate the depth of


Quick Start

Track and Flowbutton

Calculate Flowbutton

Depth Mapbutton

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pixels. If you have a sequence with very slow movement you may want to increase this num-ber. Lowering the number can also provide better results in fast moving sequences. Youshould try to ensure that there is a significant amount of camera motion between the currentframe and the Look Ahead frame.

The Output options allow you to set the number of depth layers (or underlying resolution) ofthe image produced and select the frame or frames for which a depth map will be built.PFTrack allows you to build depth data from either a single frame, range of frames or theentire sequence. Select the option you require from the drop down menu.

NOTE: All numerical dialogues within PFTrack can be altered by left clicking and dragging left andright within the dialogue box.

The Parameters settings control the time/quality scale for image generation. Increasing anyof the values within this section will increase the quality of the resultant depth map but mayalso increase the time taken to calculate it.

The Display controls manipulate the way the depth map is displayed on screen.TheNormalisation setting switches from a Local frame based calculation, in which the grey val-ues from white to black are based on the nearest and furthest pixels in that frame to Globalthat sets the values based on the nearest and furthest pixels in the sequence overall.

The Nearand Far Plane settings change the weighting orfocus of the depth map convertion to a grey-scale image.Increasing the Near Plane slider will adjust the start point ofthe grey-scale image, setting the slider to 0.1 will push thestart point of the image back 10%.This is a way to increasethe accuracy of the limited precision grey-scale image in afocused area. Decreasing the Far Plane slider has the reverseeffect, in that it pulls the end point or far position of thegrey-scale image back towards the camera.After altering any settings clickStart to generate a depthmap.

Once generated you can use the 3D window in PFTrack to visualise the depth map and seewhere pixels have been placed. If you do not get the results you expect you can alter settingsand re-calculate the depth map, possibly after adding extra user-features into the solution inthe problem areas.

Grey-scale representations ofdepth maps can be exported as

standard image formats.To exporta depth map as a grey-scale imageor an ascii-text file containing 3Dpoint cloud data right click on theDepth Map icon in the ShotWindow to open a dialogue box.You can also save a geometricdepth mesh using options found inthe Export window, details ofwhich are given in the ExportingData section of this guide.


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Basic Image ModellingIntegrated into PFTrack 3.5 is the ability to carry out image based modelling within the appli-cation. Image based modelling is the process of using camera data and visual references to

build up 3D geometry and meshes. Unlike other systems, PFTrack now has a complete set oftools for carrying this out, making it very easy to build up even complex geometry quickly,using just still or moving images as a start point.

Image modelling is an ideal tool for pre-visualisation and animation planning as it allows ani-mators to quickly build up an accurate 3D environment from background plates. In additionto matching the geometric characteristics of a background, you can also extract textureinformation from the image and map it onto the corresponding geometry.Textures can bereconstructed from multiple frames in the case of a moving image.This means if a texturewas visible at any point in a sequence it will be placed on the 3D geometry in every frame.The quality of the textures has a direct relationship to the format and resolution of thefootage you are using.

The first step in building a modelis to track and solve the cameramotion. In the case of a still image

you do this using the focal lengthestimation tools (see the refer-ence manual for details). Usingthese will often help produce abetter result when modelling, aswell as orientating the groundplan for you.

If you want to place objects on a

ground plane, it is important tomake sure that you correctly ori-entate the scene before you start building your model. Geometry will be imported in thesame orientation as your scene and good positioning of the ground plan can make building

your model much easier.You can use the new orthographic views to help with this. Once thisis done you can switch off the user features etc., in the View menu to give you a cleanerinterface within which to work.

From the Modelling menu select NewPrimitive and you will see a list a primi-tives available.You can import other geo-

metric models using the Add Primitive option at the bottom of the menu. PFTrack currently

supports the import of Wavefront OBJ files, which can be exported from most common 3Dmodelling applications.You can also open the modelling toolbar by selecting the PrimitiveToolbaroption from the Modelling menu. Select a suitable primitive and you will see it dis-played into the main view window.You will also see that the modelling control menus haveappeared in the bottom left hand corner of the main view window.

PFTrack 3.5 features a new Auto-Mesh modelling tool.This will triangulate a set of featurepoints and build an editable mesh from them. To use this, lasso a set of feature points andthen press the "Build Mesh" toolbar button (in the Modelling toolbar). The points will be tri-angulated from the point-of-view of the current camera position. This is very useful when try-ing to model organic shape or topology.


Quick Start

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The first drop down controls the way the geometry is displayed,Hidden Line is the default with the other options being prettyself-explanatory. The next drop down menu controls the way theediting tools affect an object. The default is Object Edit.This willdeform or translate the object in a uniform way dependant onthe manipulation options selected; translate, rotate or scale.TheDeform Edit option allows you to edit a vertex point while tryingto maintain the relative relationship of the other points, but willallow the object to distort. Vertex Edit allows you to move a ver-tex independently of other vertex points, or the overall primitive'sshape. In this mode the manipulation options have no effect,however you can constrain the movement of a vertex point to an axis by holding down the'X', 'Y' or 'Z' modifier keys on the keyboard. Edit Mesh allows you to add additional vertexpoints to the primitive's surface. Select Edit Mesh and then click the mouse on the surfacewhere you want the new vertex to be placed.

When starting to build your model in Object Edit mode, the first vertex you click onwill act as an anchor. When you click and drag a vertex around the screen you willsee that the primitive moves and a small red dot appears. This dot is an anchor pointthat indicates that you want to vertex to stay in this position. If you have placed

your ground plane correctly, i.e. in a realistic ground position you can also right clickon a vertex and constrain it to ground plane before moving the primitive into posi-tion. The next vertex you move will also create an anchor point, and as you movethe vertex around you will see that the primitive is adjusted so to match both

anchor points. You can add multiple anchor points to a vertex by moving it in differentframes: this allows you to manipulate the primitive and place it correctly in 3D. Primitivesare transformed according to which of the Translate, Rotate and Scale manipulation buttonsare active.

In this example you start by selecting the nearside bottom vertex having made sure that theTranslate, Rotate and Scale manipulation buttons are selected (they appear dark whenactive), and you are in Object Edit mode. After pinning the vertex to the ground we positionit in an appropriate position, in this case the corner of the building. Once in place you canselect another vertex and start to deform the box to match the reference image below. If youwant to remove any anchor points from a vertex, right-click and select the appropriate menuoption.

Using the manipulation buttons you can restrict the way objects are deformed. Switchingmodes will also have an affect on how the geometry behaves when edited.To build the roofwe can add a new box by selecting one from the New Primitive menu option or thePrimitive Toolbar. If a primitive is already selectedthe new one will be created as a 'child' of theselected one. If no primitive is selected the newone will be independent. The relationship ofobjects is shown in the project window the 'child'objects linked to 'parents'.

Making sure that Translate and Scale are active,right-click on the bottom left hand vertex of thenew box.You will see a pop up menu with a num-ber of vertex edit options. Most of these are self-explanatory, and each option will be explained indetail later in this guide.


Quick Start

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In order to connect one vertex to another, choose the Pin to Vertex option from the popupmenu. As the mouse is moved over other vertices they will highlight to indicate that the pinoperation is possible, and a dotted line will be drawn that connectsthe vertices together (See1 below). By clicking on the vertex on the top right hand front of the 'wall' the second cubewill snap to that point(See 2 below). If it does not, the correct manipulation options have notbeen selected.

This process can be repeated with the other corners asshown in 3 & 4. Once all the corners have been pinned the'child' box will exactly match the wall box below it. We canthen start to build the roof from the 'child' box. In order topin the back corner we will have to switch the view modeto Wire Frame in order to see the back corner.We will thenend up with a box exactly fitting the primitive below it.During this process it is useful to open a 3D window as thisallows you to check the way your model is progressing.

To build the roof shape we first need to build a prism.Youcould of course import a model of the roof from a 3D sys-tem if the shape was very complex or use a Prism primitive.

Right-click on the vertex at the top left hand corner of the 'roof' box. From the drop downmenu select Pin to Self. As with the Pin to Vertex option, when the mouse moves around adotted 'target line' appears.This illustrates the target position of the vertex. Unlike Pin toVertex, Pin to Self allows vertices to merge within the same primitive. After clicking on theopposite corner at the top of the box as shown in 2 the roof starts to take shape. Repeatingthis with the back of the box to produces what looks like a single sloped roof, 3.

The next stage is to use the vertex translation tools to build a sloping roof. First change to

Vertex Edit mode. In Vertex Edit mode the Translate, Rotate and Scale constraint buttons aredeactivated, but we can use the 'X', 'Y' and 'Z' keys on the keyboard to constrain the move-ment of vertex points along any axis. We can easily identify the coordinates by looking at theaxis marker on the ground plane. Holding down the 'X' key we can select one of the top ver-tices and move it across to the middle to form the pitched roof shape. It is a good idea to usethe orthographic and perspective views to help with this. Repeat the process on the back ver-tex of the roof forms a prism as shown in 4 above.Again using the 'X', 'Y' and 'Z' constraintkeys, the high point of the roof can be moved to match the roof in the image. In this case weuse the 'X' and 'Y' keys as we don't want the roof to move in the 'Z' axis.

You will notice that the roof had an over hang and we can quickly build this by using thesame constraint keys. First we need to un-pin the bottom vertex points. To do this we right

click on the corner points of the 'roof' and de-select Pin to Vertex to switchoff the constraint. We can now use the 'X' and 'Z' keys to pull the corners ofthe roof out to the sides and forward a little.The sky light can be built in thesame way using the 'roof' box as the parent.

Selecting Edit Mesh allows the subdividing of faces, adding new vertex points.This is a usefultool when building more complex shapes. To subdivide a surface, activate Edit Mesh andselect the point on which you would like to place your new vertex

It is worth re m e m b e ring that the pri m i t i ves within PFTra ck are basic and while highly complexmodels can be built, the modelling tools are pretty simple.You are mu ch better off usingP FTra ck as a starting point to build basic geometry to be refined in a full 3D animation system.


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Once this the model is complete, youcan extract textures from the footageand map them onto the geometry. Todo this, select Extract Textures fromthe Modelling menu.

You should now have a textured 3Dmodel that can be exported to your3D animation system. The optionsavailable with the texture extractiontools allow you to best match the out-put of the model with the basefootage you are using. For example,

you can pull textures from any framewithin a sequence, meaning as long as you can see a surface at some point during asequence, its texture can be mapped to the corresponding geometry in the exported model

complete with camera movement. Textures can be extracted on a per-primitive basis by right-clicking on the primitive name in the Shot Window and selecting the menu option.

Image-based modelling primitives can also be used to provide hints for the Z-Depth calcula-tion. This will happen automatically if you have built modelling primitives and then estimateZ-Depth.

There is a new View menu option called Missing Features in PFTrack 3.5.This will toggle thedisplay of projection points for features that aren't tracked in the current frame (these arethe white dots you see in the viewer windows). This is useful for the auto-mesh image-basedmodelling, where you often only want to triangulate features visible from the camera.

Semi-automatic Lens Distortion To o lThe new semi-automatic lens distortion tool available in PFTrack 3.0 allows rapid correctionof any distortions produced by a camera lens. In order to deduce the distortion characteristicsof a lens, distortion lines can be drawn manually within a frame along a 'straight' edge (theedge of a wall or door for example). PFTrack 3.0 now provides tools to identify these linesautomatically. The distortion characteristics of a lens can be saved and reused in othersequences that have been shot with the same lens. We also provide grids that can be used toshoot a few frames of footage in order to produce a more accurate lens model. PFTrack 3.0,while still allowing lines to be drawn manually, will now automatically identify suitable linesand draw them for you. All you have to do is click on what you know to be a straight line inorder to automatically correct the distortion in the footage.

To activate the automatic lens distortion detection, select Lens Distortion from the Cameramenu to display the distortion parameters, and click the Auto Detect button.You will notice


Quick Start

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that a number of thin yellow lines appear in the frame along distinct edges.Above, the first image shows the distorted original frame.You can see PFTrack has identifiededges in the image. Click on a line you know should be straight with the left mouse button,and the frame should un-distort as shown in the second image. Sometimes the image willincorrectly un-distort as shown in the image above on the right. If this happens just pickanother line until the image appears correct. The longer the line the better the distortion esti-mate will be, so try to pick the longest straight line you can find.

If the auto detect does not at first produce the results you require youcan quickly adjust the parameters by re-opening the Lens Distortionwindow (or right click on the Distortion item in the Shot Window andselect Edit Parameters). Clicking the mouse inside the Low OrderRadial edit box and moving the mouse left and right will alter the dis-tortion model in real time, giving you visual feedback in the main imagewindow.This provides a much more intuitive method of un-distorting

footage than before, and allows you to estimate distortion by eye when there are no

straight lines available in your scene.

Editing C a m e ra F- C u r ve sUnlike many other systems full editing of function curves (F-Curves) for each camera param-eter is possible in PFTrack. This provides a means to not only identify anomalies with trackingdata, but also to correct themand quickly re-solve the shot based on the new F-Curve posi-tions.To view the camera F-Curves, click the F-Curve button above the time line and open upthe viewer by moving the horizontal bar above the timeline. F-Curves can be viewed alto-gether or individually by selecting the corresponding item in the Shot Window. To view multi-ple curves at the same time, click on Motion F-Curves, Translation or Rotation. Any individ-ual curve can be selected by clicking on its icon in the list.

PFTrack has a number of basic editing methods, the two main ones are smoothing and inter-polation. Added to these you can simply click on a point and drag it in the F-Curve view win-dow to adjust its position. Smoothing is applied to a range of frames and interpolation isapplied between spline keyframes.

SmoothingIn order to smooth an F-Curve the first step is the select the range of frames to be smoothed.Click on the first frame you want to smooth with the left mouse button and drag the mousealong to another frame.The frames within the selection should be highlighted in yellow.Youcan now use the '-' and '+' keys to smooth/ un-smooth the points that are highlighted.



View F-Curvebutton

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Interpolation

Selecting a single point on the F-Curve and right clicking opens a pop up menu allowing youto place spline keyframes. Select Add Key in the menu then repeat this process on anotherframe. A Bezier curve is created between the two keys. A dotted line is shown representingthe old position of the F-Curve. Moving the Bezier handles alters the curve slope.

As an alternative, you can also drag select a range of frames and place the mouse over apoint on the F-Curve. Right Click and select Make Spline. PFTrack will then automaticallybuild a Bezier spline that covers the range of selected frames providing editing handles andshowing the position of the orginal curve as a dotted line.

As you edit the F-Curves, you are specifying that values thatyou want the parameters to take. Once the F-Curve has beenedited, it is a simple matter to re-solve the camera motion inorder to try to match the parameters you have specified. Thisis done by selecting Re-Solve Scene in the Camera menu orby pressing the Re-Solve button in the toolbar. This opens theRe-solve window (in version 2.0 this process was know asbundle adjustment). To re-solve ensure the F-Curve check boxis selected and hit the Start button.

It is possible to alter the influence that different aspects of

the solution have when re-solving a sequence.This is done bymoving the individual sliders to alter relative weightings. For example, if you want the F-Curves to have more influence than a constant focal length, increase the F-Curves sliderweight.

Using Survey DataTo improve PFTracks calibration calculations even further, it is possible to enter survey datameasured directly from the set.You can open the survey data dialog, shown below, by click-ing on the menu Tracking>Survey Data. When you open the survey data dialog, the left-handlist contains all the features in the shot. It is often useful to track User Features that corre-spond to the position in the real world of the survey point.

To enter the survey data for a feature, select the feature in the left-hand list and click on theadd feature button,(highlighted) and you will see a new entry in the survey table. Enter therelevant survey location for that feature in the SurveyX, SurveyY and SurveyZ fields in the



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right hand table.You need to specify at least 6 survey points before they will be used to solvefor the camera motion.

Survey points can be specified as either Exact or Approximate. Exact points are assumed to bemeasured exactly. Approximate survey points have an associated uncertainty, so for exam-ple, you can specify that the point is approximately at position (1,2,3) with an uncertainty of0.01. This would mean the the true survey measurement is somewhere between 0.99 and1.01 for the x coordinate, and similarly for the y and z coordinates

If you create a survey point after camera motion has been solved, the survey coordinatesdefault to the current feature location. This means that there is a new way of solving problemshots:

1. Solve a small number of frames in the shot2. Create survey points from the feature data3. Extend the in/out points to the entire shot

4. Re-solve for the whole camera path using the survey data.

E x p o rting DataBefore exporting it is a good idea to save the project. If the project is to be saved to a loca-tion other than the one from which it came, or the name of the project is being changed,choose the Save Project As option from the File menu then type in the new details.Otherwise you can simply hit the save button.

Exporting data is very simple. At the bottom of the Shot Overview panel you will find arange of export items. Any number of exports to any number of locations can be set up inPFTrack, making it easy to provide others in the team with the data they need in the correctlocation.You can also set up default exports from within the preferences window.

Exports are grouped in logical families, 2D, 3D and Plug-in. The target application for the datadetermines the type of export you will use. 2D exports will create 2D trac

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