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noizFACTORY
02-12-2008, 11:01 AM
Hello,
Crisp may not be the right word here but basically what i want to do is render fluid clouds in mental ray which do not end up looking too soft/blurry or less detailed.
I'm using static textured cloud banks right now and most of the containers have at least 40x40x40 resolution (some are much much higher res) with volume samples override set to 2 which has gotten rid of some blotches and noise. I've left the mental ray global settings to low quality as I've read in threads over here that the fluids quality setting (right now 2) should take care of the final render quality and not the render global settings which just increases the render times without any apparent gain in quality. I've left the filter settings at box and 1,1. Is that a reason i'm not getting sharp looking renders? Should i switch to my regular lanczos? This thing is meant for the big screen and i want to make sure that the renders hold up at that resolution.
Also, would increasing the fluid resolution beyond what i have right now, have any apparent effect?
My apologies if some queries seem too obvious. Just want to make sure i'm on the right track.
Thanks,
Sachin
Don3Don
05-07-2008, 03:54 AM
do u mean the softness of the cloud edge? If so, it's about the opacity curve, tweak it to make the cloud sharper..

and if u are only using texture cloud, (non-dynamic), higher resolution won't affect the quality much..
over 10-20 should be enough...
fedayi
05-07-2008, 06:43 AM
mental ray doesnt render out nice clouds, i would suggest you use the software renderer instead.

this is from my own little experiments. and its my own preference.
noizFACTORY
05-07-2008, 06:59 AM
Hey thank you people for still taking interest in this problem. I should have posted my solution long ago but somehow this thread skipped my mind.

Anyway, I did manage to get sharp cloud renders in mental ray by changing the filter to lanczos and using higher samples in adaptive sampling settings. Ideally, these shouldn't affect the quality of fluid renders as they have their own shading quality setting. At least thats what I had read. However, when I just started using the lanczos filter with high quality production settings I got sharper looking (non blurry) cloud renders.

Yeah, sw renders clouds pretty crisp but its slow as hell, especially with raytraced shadows. So I'll stick to mr. Thanks anyway folks! :)
untelon
05-07-2008, 05:42 PM
Hi noizFactory. I am not sure this will help but... in my experience you can get rather good results with low-rez containers and simple setups. I usually achieve crispness of the clouds by tinkering the opacity graph, specially now that you can maximize it. Truncate the curve on a perlin noise at frequency and frequency ratio around 2.4. One issue is that the sharpest you truncate the shading graph curve, the more likely you will see artifacts (black dots) on your clouds. This needs to be balance by increasing the shading quality (2 or more) and mentalray's Raytrace/Scanline Quality's min max (in my case -1 to 1). I think the following file takes about a minute to render (960x540). Hope this helps.

Jim
noizFACTORY
05-07-2008, 07:12 PM
Hi noizFactory. I am not sure this will help but... in my experience you can get rather good results with low-rez containers and simple setups. I usually achieve crispness of the clouds by tinkering the opacity graph, specially now that you can maximize it. Truncate the curve on a perlin noise at frequency and frequency ratio around 2.4. One issue is that the sharpest you truncate the shading graph curve, the more likely you will see artifacts (black dots) on your clouds. This needs to be balance by increasing the shading quality (2 or more) and mentalray's Raytrace/Scanline Quality's min max (in my case -1 to 1). I think the following file takes about a minute to render (960x540). Hope this helps.

Jim

Hey Jim,

Thanks a lot for your example file. I'll surely go through it and try to learn from it. :) Thanks again!
RoundRobbin
05-14-2008, 06:35 PM
Its optimal to have your thoughts on a single cloud, have a container large enough for it. increase the resolution to fit the quality of your render, and when it comes time to render more clouds, extend the container. But one cloud within the a fair resolution container should suffice for testing purposes. Can't wait to see your results.
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