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Panther Lily


(Lilium pardalinum)

Translucency Shading



For this assignment I wrote a surface shader that balances front and rear lighting to create the illusion of translucency. One improvement I would like to make is the automatic control of the blend amount relative to the intensities of surrounding lights. Although having control is usually beneficial, automation of the blending would allow an artist to focus solely on the lighting.





Leaf Translucency Reference Images



Light Rotation Tests


Day Time




Night Time





Displacements





Displacement shaders were added to two sections of the lily. The leaf geometry was displaced with my painted image map on the left. The stamen were procedurally displaced using a custom noise shader.

Renderman Shader




The interface to the left controls the properties of the latest panther lily shader. It differs from the previous by having a few specularity controls and the absorbance slider (more detail below). The movie on the right shows the scene light revolving around the geometry with hardware-rendered specularity. The palette with all the shaders used is below the video. The Panther Lily Translucency shader is available here.

Shader Testing


Basic Function Test




Absorbance Test




Final Test




The effect in the top left video was achieved after the shader gained basic functionality. It would determine what one side of the surface would look like and then combine it with the image on the reverse side. In the example, the intensities of a top and bottom light are animated.
The top right video demonstrates the effect of the absorbance slider I incorporated. It controls how much light intensity is allowed to pass through from one side of a plane to another. The bottom light is kept on full intensity as the absorbance value is animated.
By tweaking the absorbance amount and combining the blend feature previously created, the illusion of translucency can be believably faked. The result of the technique is to the left.

Paper & Napkin Translucency Reference Images


Images were taken on one side of the object and then held up to a fluorescent light.

 

Richard Sun / Rich Sun Productions 2007.