1. CS 534 Homework #4 References

2. Cylindrical Projection
Alpha Blending

3. Cylindrical Projection Example3

4. Cylindrical Projectionx y
unwrapped cylinder x θ f 4

5. Cylindrical Projectionx y
unwrapped cylinder y z f θ x 5

6. Cylindrical Projectionx y
unwrapped cylinder y
s defines size of the final image,
often convenient to set s = f z f x
cylindrical image 6

7. Cylindrical Projection
How to do the warping? Forward or inverse? Y X 7

8. Inverse Cylindrical Projection
(X,Y,Z)
(sinq,h,cosq) Y Z X

9. Alpha Blending I3 p I1
Optional: see Blinn (CGA, 1994) for details: I2
Encoding blend weights: I(x,y) = (R, G, B, )
color at p =
Implement this in two steps:
1. accumulate: add up the ( premultiplied) RGB values at each pixel
2. normalize: divide each pixel’s accumulated RGB by its  value
Q: what if  = 0?
A: render as black 9