Overview

Toon-Textures is an attempt to render Alice worlds in a natural, hand-drawn style. While many users may prefer photorealistic texturing, others find non-photorealistic rendering a more appealing style. Through providing multiple rendering techniques, Alice becomes a more useful tool for expressing one's creative vision.
  
Traditional Alice rendering. Toon-Textures rendering.

Techniques

Toon-Textures uses two 2D drawing techniques to convey information about the form of an object -- line weight and shading. (detailed below) While these techniques are common in cartoon drawings and other 2D media, they are scarcer in real-time 3D graphics. Alice Toon-Textures was inspired by several papers on the subject of non-photorealistic rendering - interested parties are encouraged to follow the links below.

Line Weight

Toon-Textures use dynamic line weighting to give depth and shape to 3D objects. Outlines on an object's dark side (the side farthest from the scene's light) appear thicker than lines on the object's light side.    
Cartoon-Style Snowman   
without line weighting.		 Cartoon-Style Snowman   
with line weighting.

Shading

Toon-Textures use a flat-shading like filling style to give a hand-drawn look.

Example Worlds 

Toon-Textures vs. Traditional rendering
Texture Chicken
Trees
Take-Me-On

Future Work

Multipass texturing
Currently, Toon-Texturing is an all or nothing decision - an object can either be rendered in cartoon or not. Many users may wish to render single objects using a combination of several techniques. For example, one might choose to render the body of the chicken in cartoon, while rendering the chicken's eyes with a traditional bitmap. Such mixing of styles will require the use of a technique called multiple-pass texturing - a planned addition to Alice.  
Low-level Rendering
Toon-Texturing is currently working at a very high level in the system. It is not a separate rendering engine for Alice per se, but rather a method to feed Alice's rendering engine a specific style of data to produce the desired effect. By writing Toon-Textures as a rendering engine itself, we expect to see a dramatic increase in performance and find it easier to add functionality.  

Links

Interested in the specifics of how Toon-Texturing works? Want to share your own ideas about how to make it better? Send your questions to forlines@andrew.cmu.edu   

Lee Markosian, Kowalski Michael A., Trychin Samuel J., et. al, Real-Time Nonphotorealistic Rendering, Brown Univeristy, SIGGRAPH 1997   
   

 

   

  
  
  
  

 

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