Abstract
Transparent objects are simulated in ray tracing by using reflected and transmitted light rays. We present a simple technique for ray tracing dielectric materials where the filter color inside objects varies with position. The surface reflection and transmission can be specular or glossy. This is based on Whitted-style ray tracing and path tracing. We also ray trace materials where the index of refraction varies with position. This results in curved light paths which in some cases have to be computed numerically. We ray trace Luneberg lenses, and spheres where the index of refraction is proportional to 1 / r , and r is the radial distance from the center. We call these inverse spheres. We mathematically analyze the light ray paths inside these spheres, which are logarithmic spirals, and ray trace them from the inside with a fisheye camera. This camera allows rays to be shot in all directions from the location of the camera. We found that the resulting images contained one or more fractals, and our analysis allowed us to understand how the fractals formed. We rendered a number of images to confirm the existence of the fractals. As a case study, we model a vase in Maya with a high-resolution triangle mesh, and render it in our ray tracer with a variety of materials and ray tracing techniques. These include dielectric and glossy transmitter materials, a rainbow-colored filter color, and path tracing to produce colored caustics. There is more work to do with the inverse spheres. We want to ray trace them when the index of refraction at the surface is greater than one, and has arbitrarily large values. We also want to place a reflective sphere inside an inverse sphere, and find out what it looks like when we ray trace it with the camera inside and outside.