xl, yl, xr, yr don't have to be normalized but the image center has to be origin, e.g., -512 < x < 512 and -384 < y < 384. X, Y, Z has the same unit as disparity d. Perhaps this article helps:
http://disparity.wikidot.com/triangulation-geometrics
But probably you need some optimization to apply blob detection at 60fps or more. For example, you can limit the search window by predicting the ball motion.