TARDIS Compositing issues

I’m relatively new to the program but I learn quickly. The only really big issue I’m dealing with now is composition.

I’m working on a TARDIS model that will be used in an animation. I want to take advantage of the compositor to add glow effects to all sources of light, notably some windows. From what I’ve researched, I’ve learned about splitting things into layers (ex. windows layer and “core” layer). However, if I now try to blend the two layers, all four sides of the windows are laid over the TARDIS. I’m including a screenshot example of what I’m talking about. I’ve simplified it to the essentials for the sake of this thread (Input -> Output).

While I’m here, I was also wondering about other mixing issues such as transparent backgrounds. It seems that it’s impossible for a glow to extend beyond a model if the background is transparent, and in the example itself, the background is causing blending issues (i.e. the TARDIS faded out). I was wondering if this had anything to do with Ambient Occlusion.

You need to put your booth on a Mask Layer, in addition to whichever layer that it’s on. Select the booth, click M and when the layer buttons appear, hold the shift key while selecting an unused layer button. You want it on two layers because it needs to appear in the scene, but it also needs to serve as a mask to block out the unseen windows.

Then in the Render Layers panel, select the render layer for the windows and under Mask Layer select that new layer you put the booth on. It will serve to block out the windows that can’t be seen.

Thank you so much! This seems to have worked perfectly. My second question is in regards to blurring. It seems as though the effect affects the mask edges as well. If I keep it low then it’s not a problem, but is there a way around this?

Pic of W.I.P.

Blur for glare? Can you post an image of what your talking about with it messing with the masking? And what are you using the renderlayers for, is it just for the glare on the windows or is there some other reason your using them?