Keypoints detection: modelisation of features

I am trying to find a good and simple modelisation for the features extracted from 3D scans. After several tries the best modelisation seems to be given using the skew normal distribution.

Here are some examples of feature distributions and the corresponding models we get for different keypoints:


As it can be seen, it captures more or less correctly the global shape of the distributions.

Thank you to my lab mates for the interesting conversation about this modelisation issue.