Homework 6
Computer Graphics (ECSE-4750), RPI
Fall 2005

2, 1/d^2 could cause harsh rendering, since it is only true
for point sources and omitted inter-reflection
components. Instead, (a+bd+cd^2)^-1 is used, where d is the
distance and a,b,c are parameters chosen to soften the
lighting.

3, This may appear unnatural, but it is helpful to create
realistic shading effects in as close to real time as
possible. that's why in Phong's model, light regarded
addictive, ie, made up of ambient, diffuse and specular
components: I=Ia+Id+Is. We could calculate each compenent
seperately and then sum them up to get the total effect.

4, l=(1,0,0), n=(0.6,0.8,0)
r=2(l.n)n-l=(-0.28,0.96,0)