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1Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
The architectonic-style likelihood principle for
procedural development of
Cultural Heritage Virtual Worlds
ELIOS Lab
F. Bellotti, R. Berta, S. Cardona, A. De Gloria
ELIOS Lab DIBE – University of Genoa
2Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
3D urban areas
3D reconstruction of a urban area for educational cultural Virtual Worlds (VWs) or Serious Games (SGs)A trade-off between the 3D model’s realism and weight
An impressive and culturally valid experiencePhotorealistic models, weather effects, surround-sound
audio, graspable virtual objects, natural lighting system
Performance and usability problems for an SG/VW online platformAn enjoyable experience and real-time interactive
exploration
3Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
3D model details
In a highly interactive system details are not fundamental
However, in Cultural Heritage, the player is acting almost like an art detective.
Highly realistic, complex systems are costly to implement
3D modeling and texturingTaking and processing pictures (ground-level images)
4Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Travel in Europe
Involve students and teachers in living compelling adventures in a cultural SG
Easy configuration through authoring toolsEnhance the educational value also through content-creation
The artistic heritage domain involves strict requirements in terms of realism and cultural soundness
Feeling the “sense of place” for a compelling and fruitful experience
A cognitive foundationAfter a visit, a visitor typically remembers the general
features of a city, its architectonic styles.
5Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Travel in Europe styles
6Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
The Architectonic Style Area algorithm
Procedural generation of buildings for VWs/SGs based on the concept of “architectonic likelihood”
Give players the sense of being in a particular city/areaNot to implement a detailed reconstruction of every single
building, but to single out few meaningful styles– the templates out of which the single buildings can be instantiated through
statistical variations
An architecture ontology, a statistic description of the architectonic elements
Outputs: facades for all the buildings in the area
Modeler responsibility shiftFrom the 3D implementation and image texturing – to the
definition of the architectural elements and their statistical description
7Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Putting it all together
Geo-referencedGround elevated from a local 3D vectorial mapPrecise placement ensures compatibility/portability to
GISs and expansibility of the system
Few Point-Of-Interests (POIs)Rigorous reconstruction at a high level of detail
Culturally meaningful buildingsCathedrals, theaters, and outstanding palaces.
Textures for other palaces built by the ASA, a statistical template-basedalgorithm
8Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Related work
A shape grammar with production rules that iteratively evolve a design by creating more and more details
Our approach is not concerned on generating the 3D shape of the buildings, but focuses on the look of the façade exploiting architectural grammars
9Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Related works
Mueller subdivide a facade texture in a top-down manner into elements such as floors, tiles, windows, and doors
Image analysis to build semantic 3D models by detecting repetitions in the high-level facade structure
SketchaworldProcedural automatic reconstruction of environments based on semantics
10Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
ASA approach
A different point of view:identifying building templates in an area
focus on:facades rather than shapesautomation on the generation of instances by assembling
components based on a statistical description
Inline with educational aims of SGEmpowerment of users for an easy generation of content
Not exploit semantics to build 3D models from images, but use architectural knowledge to prepare semantic rich 2D textures
11Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
ASA steps
The Map: a 2D vectorial file (Autodesk AutoCAD 2004 DWG format)
3D generated by extruding the DWG polylines that represent the buildings
Height, roof shapes andfaçades textures aredetermined and appliedas results of thesubsequent steps of thealgorithm
12Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Definition of the building Templates (Styles)
Define the building templates in the areaE.g. various types of palaces, villas, churches with their frequency
The algorithm will instantiate buildings in the area out of these frequency values.
ExampleGlass Skyscrapers (20%)Plaster Skyscrapers (30%)Churches (5%)Local Style A houses (15%)Local Style B houses (30%)
13Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Characterization of each template
Constructs the texture for the façades of the buildings by exploiting architectural knowledge assembling architectonical elements
windows, portals, shops, moulding storey, frieze, baseboard, etcThe modeler provides for each floor probabilistic data about elements distribution and textures for each elementsHigher level parameters include the height of the building, the number of floors, the type of roofs, etc.
14Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Parameters’ categories
Vertical structureNumber and height of floor typesGround, first, under roof, other floors
Ground floorType and relevant density of shops, windows and doors
Other floorsType and relevant density of windows, balconies, arches, quoins, plaster. Different statistics for the different types of floors: first, under roof and others.
RoofHeight, ridge, gutter, mansard, etc.
15Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Example
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Sophia Antipolis, 11-12 Feb. 2010
Parameters’ values
For each parameter, the modeler specifies its possible values with the relevant frequency. Frequencies sum up to 1.
The relevant ortho-rectified pictures are to be provided for each value of each item (e.g. type of windows, balconies, etc.) in order for the algorithm to assembly instances of facades based on the statistical description of the architectonic components.
17Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Architectonic parameters
18Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Development tools
The ASA Builder tool is the visual editing tool that implements the ASA algorithm for procedural construction of 3D models
19Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Development tools
A tool chain1- Template CreatorProvide pictures and frequencies for each architectonic
featureOutput: an XML file with all these data
2- Façade BuilderGenerates the 3D models for all the buildings in the
ASA area. Every building is textured with a texture synthetically generated on the basis of the Template Creator statistical description
20Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Genoa
21Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Strasbourg
22Focus K3D Conference
Sophia Antipolis, 11-12 Feb. 2010
Resources
www.tieproject.eu [email protected]