Author Topic: Post-process background, with overrides?  (Read 702 times)

2021-03-03, 13:26:56

aaouviz

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I'm sure this has been discussed to death... it's at least bugged me for many, many years, but I'm still unable to figure out any good solution...

The problem; I want a Corona sky to illuminate my interior scene. BUT I want a custom (site-specific) 360 panorama to be visible in the background.

Obviously I can set the Corona Sky as my background, and the HDRI as overrides.

First problem; the weird Corona bug with noisy renders when reflect environment override is in use. Is this fixed yet? Is it close to being fixed? This seems like a pretty major problem...

Problem #2: If I want to 'edit' the background once the render is complete, I run into problems. Obviously I can save my render as *.cxr and export out the image as PNG with alpha background on. This allows me to put a custom background pic into the image in photoshop behind my big glass windows. The problem is that I lose a lot of detail in the reflections of the glass. I get matting on the sides of the window frames (and other objects that are infront of the glass windows). So I can't easily 'paste' in a background.

So, my only option left is to render in the background plates for clean, custom views out of my window. But this solution, of course, allows for no flexibility in editing my background after rendering.

Is this clear? Do others experience this paradox? Is there a solution I'm unaware of?

Many thanks for any input...
Nicolas Pratt
Another Angle 3D
https://www.instagram.com/anotherangle3d/

2021-03-03, 18:06:54
Reply #1

dj_buckley

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When I'm doing interiors, the closest I can get to what you want to achieve is Corona Sky (or HDRI) in the 3DS Max environment slot, then in the Corona Overrides - Direct Visiblity set to black, Reflection/Refraction Override is my 360 backplate JPEG with the RGB Level corrected to match my exposure etc.

Save this as EXR, load it into Photoshop with ProEXR using 'Alpha Makes Layer Transparent' then drop in the backplate.  There is still some ever so slight fringing around window frames or anything that sits directly infront of the alpha, but it's barely noticeable, certainly not the end client.

I've never had the weird noise issue with Reflection Override, unless I'm using one HDRI for light and one HDRI for reflections.  If I'm using a JPEG for reflections then it's fine.