interactive rendering techniques for focus+context visualization of 3d indoor models

Interactive Rendering Techniques

for Focus+Context Visualization

of virtual 3D Indoor Models

Graduant: Alessandro Florio - 161704 Supervisor: Nicola Conci Assistant supervisors: Jürgen Döllner, Matthias Trapp Co-examiner: Niculae Sebe

Trento, 14. October 2014

Focus+Context visualization

A. Florio Interactive Rendering Techniques for Focus+Context Visualization of virtual 3D Indoor Models 2

Basic idea:

Show selected regions in greater detail (focus)

Preserve global view at reduced detail (context)

No occlusion (all information is visible simultaneously)

T. Alan Keahey. Network Visualization Course. Indiana University. 2003

The main problem of information visualization is the insufficient space,

which restricts the user in showing detail and context contemporaneously.

The Focus+Context system allows the user to show detailed information

linked with the context, by also having the possibility to focus on other

information by interacting with the system.

Dürsteler, Juan C. "Focus+Context." The digital magazine of InfoVis.net (2002)

Motivation


Constructions* are nowadays

designed with CAD programs:

detailed indoor models are

available

In most applications only the

external shape is used (e.g.,

buildings: used in city models)

Usage of BIMs through a building’s life cycle

http://www.climatetechwiki.org/sites/climatetechwiki.org/files/images/teaser/ building_life_cycle_teaser_image.jpg

*: not only buildings are considered

Indoor models could be exploited in many phases of the construction’s life cycle, but: Too much information complicates

understanding

Occlusion of elements of interest Indoor models are already available in Google Maps

The IFC data model


Open, international

standardized

specification for BIM*

data exchanged

between participants in

buildings’ lifecycle

Entities with semantics

in an object-based

hierarchy

* Building Information Model

IFC: Industry Foundation Classes

Graphical representation of the structure of

different elements in an IFC dataset

Overview


Five rendering techniques for interactive Focus+Context

visualization of IFC models:

Using two libraries for 3D scene management and GUI:

a) b) c)

d) e)

a) Semantic-based cut-away views b) LODs c) Semantic-based ghosted views d) Exploded views e) Highlighting of single objects

F+C Rendering Techniques


Semantic-based cut-away views

IFC objects as osg::Switch nodes in the scene graph

All elements of the selected type are switched off/on

Example of semantic-based cut-away views



Levels of Detail (LODs)

Predefined configurations of cut-away views

Exemplary LOD

Hagedorn, Benjamin, et al. "Towards an indoor level-of-detail

model for route visualization.„ Mobile Data Management: Systems,

Services and Middleware, 2009. MDM'09. Tenth International

Conference on. IEEE, 2009.



Semantic-based ghosted views

Intermediate representation between switching on and off

2 techniques: transparency, wireframing (type-based)

Example of semantic-based ghosted views



Highlighting of single elements

All elements rendered

with ghosted view

Selected element

rendered opaque

Multiple selection possible

Example of how a single element is highlighted



Exploded views

The transformation matrices of storey nodes are updated

with new translation factors depending on floor’s height

Normal building representation Building rendered using exploded views



Exploded views (automatic)

∀ frame { if (autoEVenabled) { bool overlap = checkBBs(); if (overlap) { while (overlap) { zOffset += DELTA; overlap = checkBBs(); } } else { while (!overlap) { zOffset -= DELTA; overlap = checkBBs(); } } } }

Explanation of how automatic exploded views work



Combination of techniques

All the implemented Focus+Context visualization techniques used simultaneously

Demo


Possible applications


Visualization for facility/disaster management:

Render with focus the elements which should be managed

or taken into account

Render as context the spatially related elements

Cut away the unnecessary or occluding elements

Possible visualization in facility management Possible visualization in disaster management

Performance evaluation


Model

# lines 82237 98515 62678 49675 1845439

loading time 19 s 20 s 21 s 13 s 83 min

frame rate (LOD4) 8 fps 9 fps 3 fps 3 fps 0,12 fps

frame rate (LOD3) 17 fps 24 fps 6 fps 10 fps 0,47 fps

IFC elements 117 92 483 782 14882

drawables 17201 24148 47134 15932 1504707

Measurements on: 3.1 GHz Intel® Core™ i5-2400 processor

8GB RAM NVIDIA GeForce GT630 with 2GB video memory

Windows 7 Enterprise 64-bit

Performance depends on:

Quantity of elements

Complexity of elements

Quality of the dataset

Future work


Storey-based LODs

Focus lens

«X-ray» lens

Clipping volumes

Conclusions


Semantic-based Focus+Context visualization:

Hide or make only slightly visible entire types of elements

Facilitates perception of important scene elements

Retain reference objects as context to spatially relate

Interactive rendering:

Configuration settings can be changed at runtime

View-dependent visualization (automatic exploded views)

Tool for effective exploration of 3D indoor models

Sufficient rendering performance, space for improvements

Questions?


Thank you for your attention!

interactive rendering techniques for focus+context visualization of 3d indoor models

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