Our goal is to generate the ocean surface image. So we begin at a transparent
object.
First begin with a transparent sphere. We add transmission and reflection ray
on it. Light source is 4 point light sources. The refraction index is 1.33.
This
sphere also has more on reflection.
Then we change the point light source to area light source. We also get rid
of the specular term of wall. By the speed up of bounding box, It take 7 sceonds
to rendering this (600x450) image on a 1.5G PIII computer. We use 1.52 as refraction
index. It is looks better.
Add soft shadow. But there are some noise on the shadow. Because It use only 4
samples per pixel. It takes 47 seconds.
Use photon mapping, we got the caustic under the sphere. Use 500,000 photon is
pretty enought for this caustic. But for other complicate scene, we need more
photon. (Such as radiosity scene).
Now we use two sphere, one is mostly transparent, another is mostly reflective.
Use only 1 sample per pixel per area light source patch. The area light source
is composed by 4 triangle. So there are 4 shadows for each sphere. This one takes
17 seconds.
Photon Mapping, and 160 sample per pixel. The shadow is pretty smooth.