OTOY Forums

Hi

I'm new to Octane and just trying to do some renders of glass with some caustics on the ground but I just can't seem to get it to really show up. My quick test scene render here is done in 2019.1.2 , PMC kernal, specular material, one quad light off to the left. There's a hint of some caustics there but it's pretty subtle and undefined. I've kept the caustic blur at it's default too of 1%.

I had been looking at caustics in Redshift, see pic attached of a Youtube video, and it looks absolutely brilliant.

Can Octane replicate this?

Thanks.

Hi,

I'm not an expert in how the caustics internals work, but if you share the scene we could take a look at it to check what can be done.

Thanks,
-Juanjo

It looks like your light source is large and weak. Try making it small and bright. In the tutorial they've got a pretty bright, small light source, based on the shadows it casts. With a diffused, low power light source, you don't get much of a caustics effect, in CG or in real life.

Thanks, I did some more tests and you're right, it needs to be a smaller and much brighter light. Also after many tests I found that using the Pathtracing kernel was fine, and the key was to make sure that diffuse bounces needed to be higher than the default of 8, it seemed 12 lightened the shadows a bit. The main key though was the GI Clamp setting. I've been putting it down at 1 sometimes, or maybe 5 which most of the time is fine and speeds renders up. But with caustics the GI clamp needs to be much higher, I found that 500 or 1000 or higher was very important to get the caustics to appear brighter. I tried the PMC kernel but found that to be too slow, and the shadows seemed darker so I didn't use it on this. I've attached the scene files here in case anyone finds it useful.

Forgot to turn the spec on again