Is there a best method for Compositing glasses into an actor to allow for the ear bands of a pair of glasses to disappear behind the actors head say if they turned to the left or right significantly. I can't use a mask as the glasses are fully transparent (like workman googles) so the part that needs to disappear is visible through the lens if that makes sense, image looking at them head on and they turn 45 degrees left.
In short I tracked the head in pftrack, exported data to 3ds max, attached the glasses to the motion pfdata and rendered out to exr using vray for all elements. This might be more of a 3ds max trick, apologies if it's the wrong forum. I have modelled the actress head to match the glasses up if that helps with somehow masking off the arms to the glasses.
I've seen they manage this well in a film like gravity for example where the helmet glass is CGI, yet the far side will pass behind the actors head creating the illusion the head is surrounded by this.
I would suggest rendering the front of the glasses (lenses and frame) separate and the ear bands on a different pass. Then use masks to sandwich all and different transfer modes and opacity - sometimes you may have to duplicate the same layer and use one with low opacity and the other with Overlay or Screen to bring highlights in and give the right transparency.
You would have to slice the Bubble with a plane that is oriented to the camera (always facing the camera and set at the distance where it intersects the bubble at the edge of the bend of the glass and it rotates around the center of the bubble). This way you can render the front and the back of the bubble on separate passes.
Thanks, makes sense. It's all about creating solid tracking data to work from is key then, all this is achievable then I can see. I eventually got a solid track on the actress but wish now I placed marker dots down the nose also which would have helped. Using a dust and scratch matte they were easy to removed in the end, which was my first concern of having too many. Thanks again