Problem trying to create water material Tweet

[mattbakeratomiq]

Hi, I'm new to using Octane, and I'm struggling to find detailed and helpful documentation on the renderer in general, but specifically on how to create realistic/physically accurate water. I'm using the 3DS Max plugin but figure this relates to the standalone too. The LiveDB materials don't look realistic - i.e. they are very dark and are a consistent colour regardless of the depth of the water. The best I've been able to do is turn on fake shadows and place a red colour in absorption (which creates blue water), but is this physically accurate? I'm not sure why I need fake shadows on.

[bepeg4d]

Hi,
your approach is correct, leave the transmission at 1 and use the absorption value to give a color to the water based on the scale parameter.
When the light has to travel, it's a good idea to use the Gaussian spectrum node instead of a classic RGB node, here you can find some info:
viewtopic.php?f=87&t=52449
The fake shadow option is needed to speed up the approximation and let the light to come in, otherwise it will take too long to be useful.
Don't forget to switch to Path Tracing or PMC kernel and also play with the Specular and Glossy depth.
Anyway it is always an approximation so it cannot be physically accurate, but physically correct
ciao beppe

[mattbakeratomiq]

Thanks so much for your reply Beppe! That's very helpful! I'm surprised that the LiveDB materials don't seem to use this method, at least from what I can tell. Is there a better source for information on Octane other than the manual? I'm not finding the manual very helpful at all. Also if you would be so kind as to point me in the direction of information on caustics I would be very grateful. I can't seem to get a strong caustic effect with my water, and haven't had luck searching the forums.
Cheers! Matt

[bepeg4d]

Hi,
You know, the Live DB is not moderated, so, sometimes the materials are not properly created, probably we need a rating system
In my opinion the online documentation is not so bad:
https://docs.otoy.com/#rOctaneRender%20Universe
OctaneRender is still young and quite fluid because of its continuous development, so the documentation is not an easy task, but Otoy is working hard to improve also this aspect.
About coustics, first of all, you need to switch to the PMC kernel, since Path Tracing is not really good in this aspect.
Then you need a tiny light source, like the sun or a mesh emitter not greater then 10 cm, otherwise the coustics will be blurred and difficult to be seen.
On the PMC kernel side, you need to know that is not possible to reduce the GI Clamp value to speed up the render, because the caustics will be cutted.
The Parallelism value must be set to 1 and you can slightly increase or decrease the Coustic blur value for speeding up a bit the calculation, in general , not greater then 0.025.
A value of 0 gives sharper caustics.
I hope that this is enough for you for starting to work with caustics, let us know if you have more questions
ciao beppe

[mattbakeratomiq]

Thanks so much Beppe! I really appreciate it. I was using a hdri image so perhaps that was the problem. I'll apply your suggestions when I get back to work on Monday. Thanks again!