Work in progress: In order to systemize the influence of the Silhouette  on the shadow image I wanted to know how the average Silhouette  looks like. Therefore I calculated the mean of all greyscale values of all images. The resulting image looks like this:

Although this grey blob is not particularly spectacular it improves the workflow of my experiment quite a bit, since now I can use different variations of this blob as alpha map to run some tests:


big todo for me (Andi): Blender Cycles seems to have some issues with alpha maps recently. Have to find a solution for that.