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Ok, once again, here’s another mr production shader setup, this time concentrating on refractive materials for post compositing.
(There is a scene to download with maps.)
You got your background picture, a matching mirror ball picture which both go in the Environment Switcher in the usual way with the BG image in the mi camera map thing.
Then you make an MSR material, put another env switcher in it’s background slot, and in those two slots, put the mi camera map shader with the BG image, yes, that’s right, in both slots. Check “Force Transparent Alpha” for these.
Make MSR object in your scene, stuff to represent objects that are in the BG picture, the ground, walls, or whatever there is.
Try to cover as much of the BG as possible, this is important with refractive materials in the scene. Reflections can use the chrome ball for any of their faces ‘cos they all face the camera and have a reference point on the ball. With refractions however, you see right through to backfacing faces where the chrome ball has poor, or no resolution and you will see the rear-end of the chrome ball in refractions (not pretty). The good news is that the areas with poor coverage from the chrome ball are covered by the BG image, so get it covered with MSR objects. If there isn’t much in the scene or a lot of sky, then make a big vertical plane at the back with MSR mat for the sky.
Do a camera match using your preferred method, I just quickly eyeballed it here.
Make sure all the BG stand in objects have the MSR mat applied, and put your nice A&D glass mat on your render subjects. As I said earlier, I don’t want transparency to propagate to the alpha on my glass, so uncheck it if it’s on, I also use solid, not thin walled, and also use Max distance with colour at max distance for more realistic filtering of solid glass.
Do a render, and it comes out on the BG like pic #1.
The alpha channel has solid objects like pic#2
But I don’t want Max to comp it. I want to do it in PS/AE/Combustion/Fusion Etc…
Yes, this was just a test render to get a preview of how the comp may look, you may want to tweak a few things and do some more test renders before you do the final.
So, when you are ready for a final render, go to the mat editor, find those env switchers, uncheck the Background maps so they use the black colour swatch instead, pic#3, leaving the Environment maps active.
That should render like pic#4, on plain black alpha.
Load it into your chosen compositor with the original BG footage, and get something like pic#5, with those refracted images in the glass objects.
But I still insist that I want to use transparent alpha to do this
That’s OK for thin walled stuff, bubbles, sheets of flat glass, anything that is clear doesn’t create a lot of distortion. It’s also OK if the BG is a flat colour like the photo of the plastic thing.
But in a scene like this with thick solid glass, or one with frosted glass, using an alpha channel like pic#6.
Will result in a comp like pic#7.
All that hard work setting it up for realistic refractions was a waste of time, it just looks like thin wall.
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