Radiance Equation 1 Outline Introduction Light Simplifying Assumptions Radiance Reflectance The Radiance Equation Traditional Rendering Solutions Visibility Conclusions 2 Overview Polygons Planes Creating an object from polygons 3 No More Spheres Most things in computer graphics are not described with spheres! Polygonal meshes are the most common representation Look at how polygons can be described and how they can used in ray-casting 4 Polygonal Meshes 5 Polygons A polygon (face) Q is defined by a series of points [ 0 , 1, 2 ,..., −1, ppppp nn ] = (),, zyxp iiii The points are must be co-planar 3 points define a plane, but a 4th point need not lie on that plane 6 Convex, Concave Convex Concave CG people dislike concave polygons CG people would prefer triangles!! Easy to break convex object into triangles, hard for concave 7 COP 8 Why Triangles? In general for an object representation (bezier, CSG) is it far from easy to find the 2D projection of the shape 9 Spherical Coordinate System Differential Solid Angle dω d ω = dxdy = {rdθ}{rsin(θdφ} = (r2) sin(θdθdφ
