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Cylindrical Projection
3d coordinate -> cylinder coordinate -> warped image
3d coordinate to cylinder coordinate
if a point in 3dimension is (X, Y, Z) ...
theta = atan(X/Z)
h = Y/sqrt(X^2+Z^2);
cylinder coordinate to warped images
x' = f*theta + 0.5 * alpha
y' = f*h + yp
it is called forward mapping. this method has one problem that include holes in image.
therefore, we can use linear or bilinear interpolation..
or.. we can use backward mapping .
a result of backward maaping is better than forward maapping.
Therefore, in the following implementations, we choose the warping method based on backward mapping instead of that on forward mapping.
Experiments
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