Simulating projection on a rectangular screen at an angle with perspective distortion
In a presentation where the lighting conditions make the powerpoint projection barely visible, I would like to superimpose the actual powerpoint slides simulating the projection in the screen area.
The video was shot at an angle. Therefore, I need to accordingly stretch the projection, so that the corners of the powerpoint slides coincide with the corners of the screen. First, I experimented in a composite shot, with a jpg image of the same resolution as the video of the powerpoint. After some tweaking, I managed a quite good approximation by turning the layer of the image to 3d and by changing its parameters.
I then tried to do the same with the video of the powerpoint. The video would show only in 2d and would disappear as soon as I turned it to 3d.
(If things come to worst, I could do a sequence of images, but I would lose the animations of the powerpoint).
Does anyone know why this problem happens with the video and if there is some way around it?
Thank you in advance.