CS 534 Homework #4 References

Cylindrical Projection Alpha Blending

Cylindrical Projection Example 3

Cylindrical Projection x y unwrapped cylinder x θ f 4

Cylindrical Projection x y unwrapped cylinder y z f θ x 5

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

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

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

Alpha Blending I3 p I1 Optional: see Blinn (CGA, 1994) for details: http://ieeexplore.ieee.org/iel1/38/7531/00310740.pdf?isNumber=7531&prod=JNL&arnumber=310740&arSt=83&ared=87&arAuthor=Blinn%2C+J.F. 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