There is a boundary map between a 2D image and a 3D image. Let's say the sun light shines behind you and your shadow projects in front of you - in the plane. There is a boundary match between yourself (3D object) and your shadow (2D image).
Now let's say I want to know what is the volume of head from the information of your shadow image. let's assume I am able to segment or isolate the image shadow of your head. How can I calculate the volume of your head image? Thanks.