Generating Sinewy Networks using Environment-Sensitive Automata Anthony Gaarenstroom Bachelor of Software Engineering Honours Project 2006

2 Introduction  Computer generated images have enjoyed much use  Visual Art  Animations and Movies incl. special effects  Generating realistic models of plant life is an ongoing challenge  Simulating conditions such as light and object interaction helps to improve realism  A sinewy network is a model that has an organic structure -> 2

3 Presentation Outline  Background  Software  Voxel Environment  Sinewy Network Model  Effects of Light  Rendering images using POV-Ray  Creating Animations  Future Work  Conclusion

4 Background  Simulation of vine growth created by Ned Greene. [1]  Uses a voxel environment.  Limitations:  Light only calculated based on the sun.

5 Aims  Produce software that can generate a sinewy network around an existing 3D model.  Should be able to wrap around the model as well as avoiding collisions with it.  The sinewy network should be affected by light energy is present in the environment.  The output can be rendered, and an animation can also be produced that shows the growth of the sinewy network.

6 Sinewy Network Generator  Written in C++, using OpenGL to display output.  Made up of three sections  Read in model and initialize environment  Generate sinewy network  Output and render final image

7 Voxel Environment  Stores information about objects in a grid of voxels.  Voxel => Volumetric (3D) pixel  Two types of objects  3DS Model (Taken as input to the Software)  Sinewy Network Model  When a model is created, the voxels it occupies are given a new value.  Collision detection is now easy…  By examining the contents of a voxel.

8 Voxelised Model

9 Sinewy Network Model  Modelled using a dynamic node-based structure.  Each node can have multiple child nodes.  A node represents a segment of the sinewy network.

10 Process of Adding a New Segment  Choose a large number of random directions  Check to see that none of them intersect with any other objects  Calculate which one is the most suitable  Create a new segment Tile the new segment into the Voxel Environment

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12 Effects of Support by 3DS Model Good ChoiceNot Very Good Choice Awful Choice

13 Effects of Light  Previous implementation used only one light source.  SiNGe can create any number of light sources.  Can be placed anywhere in the voxel environment.  Can either enhance or inhibit growth.  Will affect the final appearance of the sinewy network.  Light values are calculated for each voxel at the start of the program.

14 Enhancer (Positive Intensity) Good ChoiceNot Very Good Choice

15 Example of Light Growth Small Enhancer Large Enhancer Large Inhibitor Starting Point

16 Rendering Images using POV-Ray  Persistence Of Vision Ray-Tracing tool  Uses an object-driven language to define  3D Objects  Lights  Materials  Textures  SiNGe creates files that can be read by POV-Ray.  Can manually edit appearance of 3D model and sinewy network in POV-Ray.

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18 Future Work  Adding textures  The appearance for the sinewy network is decided by an RGB value.  Every segment could instead have a texture.  Using ambient light  Currently light value are only calculated if in direct line of sight with light source.  Should be calculated with ambient light in mind.

19 Conclusion  Aim:  To create software that generates sinewy networks while taking environmental factors into account.  Software produced: SiNGe  Models sinewy networks that:  Can both avoid and wrap around 3D virtual objects.  Have their growth either enhanced or inhibited by a variable amount of light sources.  Can be exported either as a single image or an animation to be rendered.

20 References [1]Greene, N. (1989). Voxel Space Automata: Modeling with stochastic growth processes in voxel space. In Proceedings of SIGGRAPH ’89, Boston, MA, USA, July 31-August 4, 1989 (pp ). New York, NY, USA: ACM SIGGRAPH Question Time! Question Time Question Time!