Filtering out HDRI envoronment Tweet

[ArchPrime]

I am doing my head in trying to figure out how to render an interior + exterior model scene with a camera inside looking out a window and adjacent open door at some trees, using an HDRI texture environment as the sunlight source , but leaving no direct trace of that image visible as a backdrop/sky in final image - to allow substitution of a photo as the backdrop in Photoshop

I can switch off portions of sky that have nothing in front of them easily with the Kernel[PMC] => Keep Environment toggle.
For some reason this does not affect portions of the environment seen through glass

I get the impression that achieving this involves concepts like 'render layers', 'alpha channels' or 'render passes' , for which there are a bewildering multitude of cryptic variants and permutations, but with no tool tips hinting at the specific purpose of any of these functions.

Randomly experimenting with these, I can degrade my image in a multitude of ways by switching off almost everything but portions of environment seen through glass - none of them seem very useful

I discovered I can render just the the environment and model seen through glass by selecting the 'refraction' renderpass, which seemed to narrow things down, but toggling the refraction renderpass function to 'off' in Kernal[PMC] => renderpasses does not switch this renderpass off. In fact it does the opposite - it switches off every renderpass but the refraction renderpass.

The refraction renderpass is apparently the one thing that will survive any setting


Scanning through tutorials posted in other forum areas, I can't seem to find anyone recognizably addressing my particular objective

This surprises me, as I would assume just about everyone doing architectural visualization must need the ability to do exactly this same thing sooner or later?

Am at all on the right track?, and how do the pros render everything other than environment AND refracted portions of the environment?
Also, at least as importantly, how do they switch off refracted portions of the environment without also loosing refracted portions of the model seen through the same glass?

[Schnitzelhorst]

Hey ArchiPrime,
i have the same Problem with all my architecture projects, and i didn't find any solution for this Problem. !!! I think it is actually not possible , to get out the HDRI from the Refraction channel. The only option is to use the "glass fake falloff" Material form the Live DB. But this is only a fake glas and not really the best option. But it produce a Refraction pass without the HDRI....

[face_off]

For some reason this does not affect portions of the environment seen through glass

Tick "Affect Alpha" in the Glass Specular material, then enable Alpha Channel in the Kernel settings.

Paul

[ArchPrime]

For some reason this does not affect portions of the environment seen through glass

Tick "Affect Alpha" in the Glass Specular material, then enable Alpha Channel in the Kernel settings.

Paul

Awesome! Thanks Paul