If you have a map from a mesh into the 2D plane. How do you measure its distortion? I know that theoretically what you do is express the differential map of the transformation then use SVD to figure out your components and then find the magnitudes of the principal axes.
But how do I even define the differential map on a mesh?
When talking about distortion I mean the metrics of the differential map. i.e. things like the eigen values of the matrix obtained from the matrix representation of the differential map.