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VSFX 319 - Programming Models and Shaders

Matrix Composition in Renderman Code

Project Summary:
A demonstration of the basics of scripting shapes RenderMan scene description (rib) protocol. Writing rib files by hand focuses attention on the use of color, opacity and the fundamental concepts related to xyz coordinate system. The preliminary renders have been done using basic shading so that the geometry can be more easily seen.

Results:
Click on the image to the right to see the final render.

Basic Geometry

The basic shape of the "trix". It consists of 3 cylinders, 3 spheres, and a torus.

Here is the first of many iterations used to build the final grids. I've just duplicated the trix twice to make a small group.

Below is a small group is again duplicated to make a full line, the line is duplicated to make a full plane, and the planes are finally stacked one in front of another to make the full grid.


Here is the final grid layout with the matching code (some of it has been trimmed out for brevity).

Basic Shading and Lighting

Below at left is the geometry with a basic plastic surface shader. To keep things simple and to clearly illustrate the geometry this basic shader was fine. Next came the actual lighting of the scene. First, I rendered my occlusion pass. In the center is the unclamped occlusion pass which caused some areas, particularly the planes further back, to become too dark. On the right is the clamped occlusion which kept the darkness above a certain point so that everthing is visible.

   

At first I used depth map shadows because of some glitches I was having with ray tracing. Below are the .tex files generated by Cutter for each of the three shadow-casting lights in the scene. Ultimately I didn't need them because prefered the ray-traced shadows but I feel they serve as a good illustration of the z-depth of the scene from the point of view of the lights. On the left is the main light, the center is the left red light, and the right is the right blue light.

   

Advanced Lighting - Shadows

After rendering out pass after pass with depth map shadows I did a visual comparison of them versus ray-trace shadows and felt that, despite the longer rendering times, I prefered the ray-trace shadows for their sharper edges. I think it echoes the hardness of the grid well. What follows are renders showing each of the 4 lights in the scene on their own along with their code. Later, we will see how they all worked together and layered over each other to produce the final image.

Main White Light

Left Red Light

Right Blue Light

Dim Fill Light at Origin

All Lights On and with Depth of Field added

Below are the final images. The first is with all 4 lights on and interacting with each other. The second is the same image but with depth of field applied. I focused on the second row back to add to the dimensionality and sense of depth of the image. To me, the image feels unfinished without it because of the many different layers of geometry and lighting.