Rendering a scene and writing the 'Z-buffer' into an EXR file using 'Blender Cycles', I get a depth map. That depth map differs from the depth map which is produced by 'Blender Render'. Given its shape, I was assuming that the depth map corresponds to the 'sight ray's length'. However, that did not work out.
I derived my formula as follows:
ys [px]: y-coordinate of the pixel cy [px]: y-coordinate of the principal point. d [m/px]: density, i.e. length / pixel on the camera sensor (y_size [m] / y_size [px]) f [m]: focal length zs [m]: length of the 'sight ray' zc [m]: orthogonal distance to lense's plane (z-coordinate in camera centered coordinates)
But, that does not seem to work out. What am I doing wrong? What would be the formula?