Geometry Synthesis

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# Geometry Synthesis - PowerPoint PPT Presentation

Geometry Synthesis. Mathias Ricken Rice Undergraduate Scholar Program November 11, 2003. Overview. Computer-Generated Geometry Uses Creation Previous Work Landscapes Mazes Problems Geometry Synthesis Parametric synthesis Synthesis by analogy. Computer-Generated Geometry. 1.

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### Geometry Synthesis

Mathias Ricken

Rice Undergraduate Scholar Program

November 11, 2003

Overview
• Computer-Generated Geometry
• Uses
• Creation
• Previous Work
• Landscapes
• Mazes
• Problems
• Geometry Synthesis
• Parametric synthesis
• Synthesis by analogy
Creating Geometry
• Hand-Crafted
• Computer games

1 Man-Year for 40 hours of game play 2

• Automation
• Lower costs
• Better training
• Higher replay value
Landscapes
• Height Map
• Matrix of numbers
• e.g. one per square foot
• Numbers

 Elevation

• Filters
• Smoothen or roughen landscape
• Add rivers and lakes
Mazes
• Recursive Backtracking
• Regular grid
• 2-Dimensional
• Creates perfect mazes
• All cells connected in exactly one way
• No loops

algorithm explained in extra slides

Problems
• Landscapes
• Large scale, but low detail
• Only natural, not artificial
• Mazes
• 2-dimensional
• Small scale
• Not reminiscent of human architecture
Proposed Project
• Create meaningful geometry
• Similar to human architecture
• 3-dimensional
• High detail
• Algorithms
• Parametric synthesis
• Synthesis by analogy
Parametric Synthesis
• Create a network of rooms and corridors
• Generalization of DungeonMaker algorithm 4
• Tunnelers, agents (“robots”)
• Randomly
• Probabilities controlled by parameters
• change direction
• create rooms
• create branches
Parametric Synthesis
• Generalize
• 3D, not 2D
• Not grid-based

4

• Examples of Parameters
• Frequencies
• Dimensions
• Angles
• Alignment
Synthesis by Analogy
• Automatically enhance bare geometry created by parametric synthesis
• Use design templates
• Add colors, patterns, details

5

Texture Synthesis by Analogy
• Given small texture, create arbitrarily large similar texture
• Few visual flaws
• Similar to a jigsaw puzzle
• Look at the surrounding pieces (neighborhood) and pick best match
• Does not have to be perfect fit
• Pieces can be used more than once or not at all
Texture Synthesis by Analogy

Template

Synthesis Target

• Randomly pick first color
• Move left to right, top to bottom
• Pick neighborhood that matches best
Texture Synthesis by Analogy

Template

Synthesis Target

• Randomly pick first color
• Move left to right, top to bottom
• Pick neighborhood that matches best
Texture Synthesis by Analogy
• Large features require large neighborhood

Source

5 x 5

7 x 7

9 x 9

6

Geometry Synthesis by Analogy
• Geometry can be represented by matrix
• Distance to next surface
• Implicit representation
• Positiveinside
• Negative  outside
• Zero  surface
• Convert geometry into matrix
• Apply synthesis by analogy to it

7

Geometry Synthesis by Analogy
• Previous research in two dimensions

8

• Generalize from 2D to 3D
• Improve speed
Editor
• Build application
• Graphical user interface
• 3D display
• Support all synthesis steps

9

Notes

[1] Lord of the Rings. New Line Cinema.

Beasts. Comp 460, Rice University.

Midfield Terminal Complex. Southwest Florida International Airport.

Dynamic Flight Simulator. Naval Warfare Center, Westminster, Penn. United States Navy.

[2] Rollings, A., and Morris, D. Game Architecture and Design.

[3] Terragen. Planetside Software. http://www.planetside.co.uk/terragen/

[4] DungeonMaker. Dr. P. Henningsen. http://dungeonmaker.sourceforge.net/

Notes

[5] Illustration. Hive Assault. Comp 460, Rice University.

[6] Wei, Li-Yi. Texture Synthesis by Fixed Neighborhood Searching. Ph.D. thesis.

[7] Implicit Modeling Editor. Scott Schaefer, Rice University.

[8] Actual synthesis result. Geometry Synthesis by Analogy. Mathias Ricken, Rice University (unpublished).

[9] Illustration.

Extra Slides
• Recursive Backtracking
Recursive Backtracking

Unvisited neighbor to the north. Tear down wall!

• Square grid
• Start in one cell
• Pick a neighboring cell that has never been reached before and tear down the wall to it
• Remember previous cell
• If no unvisited neighboring cell, backtrack

No more unvisited neighbors, backtrack!