Hi
I think this is the correct category for this question.
Is it possible to take a photo, say of a forest, and separate a few trees in the foreground from the trees in the background so I can place an animated mesh in the middle? Is this possible to do in Blender?
Or, is there a way where I don’t have to split the photo and there’s a compositing passes/layers technique of which I am unaware?
Thanks,
AerialBot
You have to manually draw the masks for trees and other elements you want your animation to be behind. Either draw them in some outside soft (photoshop, gimp etc) and use them in compositing like masks or use the mask tools in Blender.
Basically you need a way to tell which part of your image is covering your animation. A mask is a greyscale image which with different pixel values allows you to control the effect of some node in compositor or shader. For example if you draw a mask where foreground trees area are white and everything else is black, you can use it as an alpha channel for your image and sandwitch your animation between original image and the fg part of that image so that you cover your animation with trees that are in front of it. Or you can use that mask in a shader and place the fg trees directly into your scene using a flat plane. This way you get the effect directly from render and can avoid compositing if you want to.
And just so that it is said, yes, masking is a tedious work and it is not a bug, its a “feature”. If still image is too easy, try live action 
Hi Kesonmis
Can you post a link of a tutorial you recommend for this?
Thanks,
AerialBot
Google blender masking or blender mask tutorial, you will get a bunch of stuff that gives you an idea of what and how. Can’t recommend any because I haven’t seen any of them.