Thanks for the quick answer, Mari-Anne.

The camera is floating above the ground and I do not touch its position. When I import each Poser scene, the camera does not seem to move... actually the offset in the final render is very slight... but enough to prevent me to stack the renders and to create the layers. I have not changed the default parameters for the camera (apart from moving it in the correct position, only the first time).

Giorgio

giorgio_2004 here, ksabers on XBox Live, PSN  and everywhere else.