status of airborne oblique imaging eurosdr …

STATUS OF AIRBORNE OBLIQUE IMAGING EUROSDR COMMISSION I PROJECT “OBLIQUE IMAGERY” Markus Gerke May 15, 2014

THE FIRST AIRBORNE PHOTOS …WERE OBLIQUE

First recorded aerial photograph in the US (Boston),

by James Wallace Black, 1860, source Wikipedia

Presenter

Presentation Notes

Actually the first one to take images from an hot air balloon was P. Nadar (french). First experiments in 1858. Those photos are no more available

Intuitively the operator shot from a slanted angle

Recognition of buildings In the 1930’s: USGS and

military systematically captured oblique images

THE FIRST AIRBORNE PHOTOS …WERE OBLIQUE

First recorded aerial photograph in the US (Boston),

by James Wallace Black, 1860, source Wikipedia

Fairchild T3-A camera, source

Petrie (2009)

Presenter

Presentation Notes

Actually the first one to take images from an hot air balloon was P. Nadar (french). First experiments in 1858. Those photos are no more available

1. Brief overview

2. EuroSDR questionnaire on the current status of oblique airborne imagery

3. Conclusions and Outlook

CONTENT

Vertical/nadir images: good observation of ground features and roof structures, assume constant scale Oblique images: observation of vertical structures, but occlusion more dominant, varying scale

PROPERTIES SCENE OBSERVATION

PROPERTIES SCALE

According to Shufelt (1999): Vertical images: t < 5° Low oblique: 5°< t <30° High oblique: t > 30° If (t+α) > 90°: horizon visible For mapping purpose: concentration on high oblique images which do not include the horizon

(symbols from Höhle (2008))

PROPERTIES OCCLUSION

“Self-” occlusion

visible

invisible


“Self-” occlusion Occlusion by other objects

visible

invisible

Mitigation through multiple view and overlap


visible

invisible

PROPERTIES OCCLUSION - EXAMPLE

All images © Slagboom en Peeters


PROPERTIES MALTESE CROSS CONFIGURATION

Source: Petrie, 2009

IGI Penta DigiCAM, Source: Homepage IGI

Maltese Cross configuration: one vertically pointing camera and 4 highly obliques pointing to the four cardinal directions. Used mainly for visualisation and (urban) data interpretation.

PROPERTIES MALTESE CROSS CONFIGURATION

Leica Oblique 5-camera head, source homepage Leica

Maltese Cross configuration: one vertically pointing camera and 4 highly obliques pointing to the four cardinal directions. Used mainly for visualisation and (urban) data interpretation. Companies offering such systems, eg: Track‘Air MIDAS Modular mid format systems IGI Penta DigiCam (RGB or CIR) Hexagon/Leica 5 camera head, mid format camera RCD30. RGB (plus

optional NIR in all cameras) Microsoft Osprey 5 camera head, NIR only in nadir See also January to May 2014 issues of the GIM international magazine for an overview

1. Brief overview



CONTENT

CURRENT STATUS OF OBLIQUE AIRBORNE IMAGERY EUROSDR QUSTIONNAIRE

Motivation of users/producers/sellers etc to buy or produce oblique airborne images not fully analyzed yet

1st step of the EuroSDR project on obliques: create an online survey Put online end March 2014 Today: presentation of (preliminary) analysis, selection

CURRENT STATUS OF OBLIQUE AIRBORNE IMAGERY EUROSDR QUSTIONNAIRE

Motivation of users/producers/sellers etc to buy or produce oblique airborne images not fully analyzed yet

1st step of the EuroSDR project on obliques: create an online survey Put online end March 2014 Today: presentation of (preliminary) analysis, selection Key figures of the survey: Separation user of images /software or hardware vendor About 10questions As of 9 May 2014: 127 participants

CURRENT STATUS OF OBLIQUE AIRBORNE IMAGERY EUROSDR QUSTIONNAIRE, AS OF 9 MAY 2014

127 participants, 59 from academia, 24 NMA, 15 companies

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Usage of oblique airborne images

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USERSVENDORS


Usage of oblique airborne images (end users, vs. producer)

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Presenter

Presentation Notes

NOTE Markus: diversity of possible usage seems to be regarded larger by users, not by companies

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USERSVENDORS


Usage of oblique airborne images (end users, vs. producer)

• Good agreement • Users see texturing less important than vendors • identification / mapping tasks in focus of users • other usages listed by participants

• Geological hazard assessment (rockfall, landslide...) • wetland mapping, habitat mapping, forest mapping

Presenter

Presentation Notes

NOTE Markus: diversity of possible usage seems to be regarded larger by users, not by companies


What can obliques do better? (only asked to users)

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easier identificationof objects

increase degree ofautomation

increase reliability do what is notpossible today


What can obliques do better? (only asked to users)

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easier identificationof objects

increase degree ofautomation

increase reliability do what is notpossible today

Interesting comments (apart from what we know already) • Identifying the heights of the features like trees, buildings

and etc. while editing automatically generated DSM for producing DTM.

• Collect multiview datasets, eg for BDRF measurements • Complement SAR for urban imaging • Rock surface analysis • Model/measure roof overhang


Vendors we asked: In which sense would the tasks mentioned benefit if oblique images were used?

Answers (selection): • different view on the subject which is valuable for interpretation. • exact measurements as for mapping updates do not gain from

obliques, ad-hoc measurements however do. • proper textures for city modelling • Geomarketing, 3D-modeling, urban-planning • better geometrical 3D modelling of all imaged objects • intuitive visualization, 3D effect without 3D real geometry • information about the number of floors


Most of the things to be done with oblique are nowadays done using… (only asked to users)

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nadir airborneimages

satellite images ground images ground survey(GPS/tachymetric

survey)

new application

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nadir airborneimages

satellite images ground images ground survey(GPS/tachymetric

survey)

new application


Most of the things to be done with oblique are nowadays done using… (only asked to users)

• so are these typical airborne image applications nowadays done using nadir…?

• other usages listed by participants • 5% already use oblique • 5% UAV (also oblique) • Terrestrial laser scanning

Presenter

Presentation Notes

NOTE Can tasks done today by UAV replaced by very high res obliques?


Automation, user view: In your workflow today, most

tasks are done…

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…how important is automation for you?

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essential important neutral notimportant

at all

Presenter

Presentation Notes

Clash: reality vs. need


Automation, user view: In your workflow today, most

tasks are done…

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…how important is automation for you?

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at all

From comments we see: • initial data processing (orientation, dense matching)

seems to work fully automatically (depending on software, size of block, some say it does not work)

• interpretation still the bottleneck. Differentiation between • “simple” (identification of buildings etc) (realistic to do

automatically) • much more complex, detailed modeling of complex

buildings (should still be done manually, unrealistic do let this be done automatically)

Presenter

Presentation Notes

Clash: reality vs. need


Importance of compatibility to in-house software?

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at all

Experience with oblique processing software: how do

you rate it?

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Still some homework to do by vendors


GSD and stereo overlap

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maximum allowed GSD at image centre (cm)

Mean 19cm, but majority in the 10cm range or less

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at least 60%overlap (i.e.

stereo)

at least 70% at least 80%

But not answered by 45 participants (35%) so do they not need stereo?

Presenter

Presentation Notes

Problem of the question… not asked for that


Near Infrared: would you need NIR for your application?

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Yes, in all viewingdirections

Yes, but in nadir view issufficient

No, not at all


If the nadir camera is a midformat, NIR camera: would a combination of this nadir camera and the oblique views replace

large format camera nadir flights in the future?

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Yes, I think so No, it is unlikely


If the nadir camera is a midformat, NIR camera: would a combination of this nadir camera and the oblique views replace

large format camera nadir flights in the future?

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Yes, I think so No, it is unlikely

Some comments • Yes, first of all in urban areas (3D photo realistic instead of 2.5D

mapping) it is possible, in non-urban still only nadir preferred • Yes, because obliques will increase reliability and accuracy of

products • No, because too much data for normal projects • No, because oblique will not replace high-res orthoimages

• It depends on the products requested on the market (comment

from company…)


One last issue…

UAV pops up again and again… link oblique and nadir on small areas, very high resolution


Example: BlomOblique Mirabello 2012 (earthquake)

Large area overview, details on facades (opposed to nadir) restricted details at façade/building level

Point cloud (SURE)


Example: UAV Mirabello 2012 (earthquake)

Small area only, but details at façade/building level, access unsafe areas

Point cloud (PMVS2)

1. Brief overview



CONTENT

CONCLUSIONS

Systematically captured airborne oblique images have reached the market

Big players jump on and offer systems Some findings from the questionnaire (so far?)

Views from users and vendors coincide quite nicely, users have more ideas of what to do with the images

At least in urban areas a replacement of large format images by advanced 5-camera systems, including NIR seems possible

Users see relation manned/unmanned oblique image acquisition Homework for software vendors (researchers!): Orientation of big blocks Automation of interpretation

OUTLOOK

Next step within the EuroSDR commission I – project Cooperation within the ISPRS Scientific Initiative A new benchmark dataset for multi-platform very high resolution photogrammetry (Nex, Gerke, Remondino) Objectives/Challenges for researcher/vendors/everyone interested To be benchmarked: (joint) orientation of multi-platform imagery dense image matching of (fused) datasets Other things you can do Building detection/update, City modeling, eg CityGML, texturing,

interpretation, vegetation,…., BRDF (restricted)

OUTLOOK

Next step within the EuroSDR commission I – project Cooperation within the ISPRS Scientific Initiative A new benchmark dataset for multi-platform very high resolution photogrammetry (Nex, Gerke, Remondino) (To be) captured in Dortmund: IGI PentaCam-flight by AeroWest (80/80%), GSD 10cm UAV flights in selected areas (oblique/nadir) Terrestrial images in selected areas Reference data: static GNSS, TLS, Totalstation City centre: 1300, open museum 900 airborne images

OUTLOOK

Next step within the EuroSDR commission I – project Cooperation within the ISPRS Scientific Initiative A new benchmark dataset for multi-platform very high resolution photogrammetry (Nex, Gerke, Remondino) (To be) captured in Dortmund: IGI PentaCam-flight (80/80%), GSD 10cm UAV flights in selected areas (oblique/nadir) Terrestrial images in selected areas Reference data: static GNSS, TLS, Totalstation City centre: 1300, open museum 900 airborne images

OUTLOOK

Next step within the EuroSDR commission I – project EuroSDR-specific questions could easily be linked to that ISPRS project. We appreciate any ideas and suggestions!

Thank you for your attention. Questions?

status of airborne oblique imaging eurosdr …

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