Best way to render glints

Support Lighting and Rendering
1

I have been using the technique in this thread to try and create a snow material with glints.

However I am having difficulty getting them to look right.

I have been using compositor to add in streaks onto the glints - however lighter parts of the image are also affected. I have tried overdriving the RGB values of the glints beyond 1 to make them appear brighter - but the compositor threshold doesnt take account of this since it only works on the final image which has these glints clipped to the limits of the final rendered image.

The best way I have found so far is to render a light and dark version of the scene - then use the 'dark version in which the glints are prominent to create the streaks - then composit these back into the final image. However it’s a bit of a faff.

Does anyone have any techniques for getting convincing glints on snow/glitter type materials.

This is the effect i’m after


2

First let’s understand what we see here: isn’t it a lens effect? Or maybe a little of iridescence?

3

It’s a combination of glossy reflection, dispersion and lens effect (hence why i’m using compositor for the latter - to get the streaks).

The problem is - getting the glossy reflections bright enough to trigger the compositor without affecting the rest of the scene.

It might not even be possible to get a realistic result given this appears to be an active area of research:

https://hal.inria.fr/hal-01200710/document

I was just wondering if anyone had come up with a decent and easy to implement cheat.