Building a Ray Tracer - Page Two

© 1996 Harriet Fell for CSG140 (formerly COM3370) Computer Graphics

For simplicity, all scenes are described in screen coordinates. The view plane coincides with the screen plane and the view window goes from (0, 0, 0) in the upper left to (433, 453, 0) in the lower right. The objects (all spheres in these first pictures) are placed between the screen and the viewer. The direction from the screen toward the viewer is the positive z-axis.

First Order Reflection

The magenta and yellow spheres are seen reflected in the gray sphere. No specular reflection has been added and the gray reflecting shpere appears to have a matte finish rather than a shiny finish.

View Point = (225, 225, 3000)
Light Source = (2500, -2000, 1500)
Spheres:
Center(100, 100, 50) Radius = 50 RGB = (0.5, 0.0, 0.5)
Center(150, 200, 250) Radius = 50 RGB = (0.5, 0.5, 0.0)
Center(350, 220, 500) Radius = 50 RGB = (0.0, 0.5, 0.5)
Center(250, 300, 750) Radius = 50 RGB = (0.25, 0.25, 0.5)
Center(275, 150, 100) Radius = 100 RGB = (0.5, 0.5, 0.5) reflective

Bump Map, Reflected

This is the same scene as above but a bump map has been added to the magenta sphere.

The same scene again with two spheres showing bump maps.

Second Order Reflection

The yellow and gray spheres are both reflective. The reflected ray is followed off the gray sphere to the yellow sphere the off again. We now see other spheres mirrored in the reflected image of the yellow sphere on the gray sphere. The ray-tracing code is recursive. It is eay to raise the order of recursion to causes reflections in refelctions in reflections, . . .

Specular Reflection

Specular reflection has been added using Phong's Illumination model with k_s = 0.5 and n = 15. The reflective spheres appear shiny. Varying k_s and n will give a different feel to the shine.

Polygon

A copper-colored, reflective triangle has been added to the scene. It's coordinates are:

(200, 0, 0) (433, 300, 0) (433, 0, 300)

Checker Board

A texture map has been used to make a checker board pattern on the rectangle that has been added to the picture. The coordinates of the rectangle are:

(40, 100, 15) (250, 100, 15) (250, 400, 35) (40, 400, 35)

Simpler Scene

Just two spheres,
a checkered triangle,
and a copper mirror.

One Reflective Sphere on a Checker Board

If you're going to do ray-tracing,
you have to do this once,
so here it is.

Three Spheres and Three Planes

Stripes and checks on two of the planes and the bumps on one sphere are reflected in the other two spheres.

Harriet J. Fell
College of Computer Science, Northeastern University
360 Huntington Avenue #202WVH,
Boston, MA 02115
Internet: fell@ccs.neu.edu
Phone: (617) 373-2198 / Fax: (617) 373-5121

Last Updated: December 20, 2005, 10:51 a.m.
The URL for this document is: http://www.ccs.neu.edu/home/fell/COM3370/RayTrace2.html