Hello!
I would like to start producing some virtual films. I do have a green screen and I am looking for a solution to Chroma Key.
My first concern are the feet and the shadow they cast, looks like it will be an unsolvable problem? 
If the feet of the actor are aligned in the beginning of the quad/plane then the shadow connects OK. But what if the actor is walking? Or has a stance where one foot is in front, like a skateboard.They wont be aligned then the shadow from the front foot is OK but not for the foot behind. I attach a screenshot - please take a look
I saw that in After Effects or Premiere one can distort and move the shadow. Can you do this in Unity? Perhaps a projection?
The cool thing about all of this is that the shadows are projected from a light inside unity so they are as correct as they can get.
I’m not an expert here, but maybe there is some interesting knowledge in this video until someone else responds
Waiting for people that does chroma key and has the traditional shadow issue, when using the keyed actor in unity and a real time.
Hello! In the scenario you describe, the chromakey video is just a texture displayed on a plane, so any shadows that are cast will be similar to what would be expected from a flat cardboard cut-out. You should take this into account when designing your shots.
You may be able to put some approximation of what you need with some experimentation. For example, you could duplicate the keyed plane, mirror it on the Y axis, align the feet, make it look like a shadow using some filters (desaturate, darken, blur). This would result in a shadow texture on a plane, but it would just “float” in the scene and not interact with any of the geometry.
Another possible approach would be to have an invisible 3D character model in the scene that only casts shadows to create a shadow that approximates the keyed actor’s motion.