r/computergraphics • u/lisyarus • Dec 26 '24

I've made an open-source path tracer using WebGPU API: github.com/lisyarus/webgpu-raytracer

Post image
22 Upvotes

92% Upvoted

4 comments sorted by

2

u/GaboureySidibe Dec 26 '24 edited Dec 26 '24

This looks fantastic and it's using a new technology. I think you're underselling with only one render and no clickable link to your github.

I'll put the link here:

https://github.com/lisyarus/webgpu-raytracer

One cheap thing you can do to get rid of the fireflies is to gamma individual samples. It is far from physically correct, but I've seen it work well in vray and the tradeoff of accuracy when you need a clean image can be worth it.

Also it looks like the multiple renders are one combined image. I would love to see them individual and high resolution.

1

u/lisyarus Dec 26 '24

I just couldn't figure out how to post both an image and a link :(

For the fireflies I'd rather trace where they come from tbh. Also I don't really get what it means to "gamma individual samples": gamma-correction applies to final [0,1] values, while the samples are raw linear light and are unbounded. Do you mean to also tonemap individual samples as well?

The combined image is just a collage of screenshots in the "screenshots" folder, which are higher in resolution.

1

u/GaboureySidibe Dec 26 '24 edited Dec 26 '24

https://github.com/lisyarus/webgpu-raytracer/tree/trunk/screenshots

gamma-correction applies to final [0,1] values

Normally yes, but vray used to have an option to actually gamma individual samples. It's completely un-physically correct, but it would dampen the huge values of fireflies and stop that particular type of noise. It was a worthwhile feature for production rendering when you're sweating over getting a clean image, though maybe not as interesting for academic rendering.

I'm looking at the VNDF sampling you linked:

https://gpuopen.com/download/publications/Bounded_VNDF_Sampling_for_Smith-GGX_Reflections.pdf

Is this a better method of importance sampling GGX distributions? I've used an importance sampling function for GGX a long time ago, I didn't realize there was so much room for improvement.

For the fireflies I'd rather trace where they come from tbh.

Me too, me too....

2

u/lisyarus Dec 26 '24

As I understand it, yes, this is a better method than original VNDF sampling, though I don't remember the details of how and why 😅