Stepping through the Portal with the Portal effect?
I have a scene in an upcoming short film where the main character shoots a portal onto the wall in front of him, then steps through the portal, and the cameraman "follows him through" the portal, and they both emerge outside. The room itself is completely CGI—the actor is going to be in front of a green screen. I am good with green screening and I can place markers on the green screen to track, moving the background with the camera if you get what I mean. But, how can I have him step through and be outside? I could do it with clever masking, but when he steps outside the lighting needs to be realistic to outside as opposed to the dull, more mood-lighted room he was in (which will be a CGI room composited in place of the green screen). How can I achieve this stepping through effect? How can the cameraman "step through" the portal with the actor, since it'll be in front of a green screen, then need to be outside? I wanted to do it in one continuous shot, but if I can't I can use two shots and do some editing to make it look like they just walking through.