I tracked a footage in maya and then placed a virtual object in it. Everything is fine.
But if i want to show that someone in the footage is holding the virtual object,how can i do that. Like...,if the person is holding it in his hand like a cup, his fingers should be in front the virtual object but everything else behind it.So how can i show that, because otherwise the object will seem to be stuck on his hand and not that he is holding it.

Is this called compositing; if yes- can it be done on combustion,maya or 3ds max ,and is there any good tutorial for it?

I know how to make layers from different videos but how to do that from a single video.

For example - If a monster is shown coming on the streets then the buildings which are in front of it should be overlapping it(should be in front of it) and the bildings which are at its back should be at its back.
In this we will need 3 layers(i think)from front to back they should be:
1.The buildings in front of monster
2.The monster
3.The buildings at its back

So how can we split a single footage into different layers?

Please someone help me…