rigid 2d point set alignment doesn't converge well enough

[smujiang]

Hi, thanks for providing this amazing implementation.

I'm working on align two point sets. To validate the highest alignment accuracy, I simplely create a simulated pointset (illustrated in figure as "simulated", green dots) from the original pointset (illustrated in figure as "original", red dots), and then apply the rigid CPD to align the points. Ideally the affined pointset (illustrated in figure as "simulated_affined", blue dots) should be overlap well on the red dots. However, there is always gap between the two pointsets (red dots and blue dots) even if I set the 'maxiter' very high (~200) and 'tol' very small. Could you please gave me some advice on getting higher alignment accuracy?