distorted refraction through bumpy glass done in post?

[fixeighted]

I have a problem.
I need to render a big bumpy glass object with stuff growing on it, with close macro dof needed.
Problem is I need the background in frame , distorted through the glass, which will
take forever to render.
I'd rather not do fake dof if I can help it, so the question is how to get the comped bkg to distort in
the areas where it's seen through the glass.

[super gnu]

id assume that to get something decent it would need raytracing in some way... so why not use the nice fast raytracer chaos have given you?

if the background is heavy, can you render it and use it as a backplate..

[fixeighted]

Hehe, I of course omitted the crucial fact that this is animation, so that's when the issues arise, otherwise no problemo

It's a vast landscape with a tiny hero object, making it a absolute pain, so I'm trying to figure a way
that I can isolate the hero in as many shots as possible.
Your suggestion is one I thought about but there are complications like time-lapse clouds with ground shadows, a moving sun
and other finicky bits that just make it a headache.

As ever with my projects there are curve balls aplenty, and little about this one is straightforward

I have an idea that the refracted alpha can be used to warp the bkg but I've yet to try that...

[^Lele^]

Render a UV backdrop (vraySamplerInfoTex as screen-projected BG) through the glass.
Then STmap (UVmap if not in nuke) the unrefracted environment (and likely some overscan) to the resulting UV render.

[fixeighted]

Thanks ^Lele^ I've actually done most of the shots now, with in-camera dof, with
an acceptable quality at around 15mins per frame. When I posted I wasn't sure how long the shots would be
and it turned out that most are only 2 to 3 secs long, so I am happy with the results.
I'll give your method a try though, as it could come in handy at another time

[^Lele^]

Or you could leverage the damnably quick renderer you're using daily, yes.

[fixeighted]

Well yeah it's quick but the amount of dof on some shots was pretty intense and so I was concerned at one point, mainly because
I refused to pay for a farm out of my end of the budget, so did it all myself. Denoisers weren't really an option, as it didn't do pleasant things to the glass areas
Client is overjoyed so far, so that is a win.

[^Lele^]

Dof is a strange one: when it's blurry enough, spatial contrast in the image lowers naturally, thereby giving the sampler a generally easier time of things.
For Glass denoising, remember you need to set the shaders to "affect all channels" (and forget about recomping, lol.).

[fixeighted]

To be honest I didn't even consider that affect all channels would allow the denoiser to work
properly. It didn't used to work afair...maybe I missed that email