TurbulenceFD & Octane Volume

[zoppo]

Have you checked Casey Hupkey NAB 2016 2nd presentation : at 21min he goes through the new Octane volume features with TFD. he gets a pretty good result by using emission tex & volume gradient in the VOLUME MEDIUM attributes (as oaktar mentioned eralier)

Unfortunately he deletes the fire / temperature channel before setting up the smoke, and he never turns it on again. Playing around with his scene I can't get Octane to render fire and smoke because I can't find a way to set where one changes into the other.

[speedracerlo]

I'm still having trouble getting some decent looking fire and smoke through Octane and TFD
By selecting "Use 3rd Party Shaders" everything from the LV disappears. I tried setting the shaders in the TFD container itself, but that seems to have no effect.
I guess I will try the volume medium as best as possible, but so far it has been a little confusing for me.

[aoktar]

I'm still having trouble getting some decent looking fire and smoke through Octane and TFD
By selecting "Use 3rd Party Shaders" everything from the LV disappears. I tried setting the shaders in the TFD container itself, but that seems to have no effect.
I guess I will try the volume medium as best as possible, but so far it has been a little confusing for me.

Did you read post from this topic and have you tried sample scenes? Post somethings what you get.

[speedracerlo]

I actually started getting some better results by changing the 'Scattering Phase' from 1.0 to 0
However that was increasing my render time by an incredible amount, so I tried various settings and found 0.5 to be acceptable. Render times are however still a bit slow. I think standard renderer might be faster.

I have a GTX 980 TI and GTX 970

[aoktar]

I actually started getting some better results by changing the 'Scattering Phase' from 1.0 to 0
However that was increasing my render time by an incredible amount, so I tried various settings and found 0.5 to be acceptable. Render times are however still a bit slow. I think standard renderer might be faster.

I have a GTX 980 TI and GTX 970

standard renderer is a standard renderer. Using low "volume step lenght" will make is slower because it increases details and counts of calculated steps.

[skotch]

Hi !

I would like to share some results and get some advice.
I made an explosion i would like to render with Octane. Simulation is like i'm expecting to be, no trouble with Octane neither, everything works fine. Interaction of the smoke with lights is pretty neat and fire is lighting up my smoke.
I checked Casey Hupkey NAB 2016 presentation to match his settings and found out he was true : Volume Step length for fire and smoke settings is around 0.2. So far, i'm getting good results.

But i can't get very much detail in the smoke. No matter what i do, i still get some big round results around the edges and most of the small details are gone in semi-transparent smoke.
When i try some test files shared in the forum, i can notice the same kind of results. Small details are gone and i would like to know if there is a way to get them back.
So far, i'm rendering some extra pass with Atmosphere pass in Standard Renderer and composite it in post.

Here is a picture of the simulation.
There is a lot of detail in it, this is an 2x upres simulation.


My settings are OK. Volume Step Length is at 0.3 and Density at 2000 to get volume density as i would like to be.
I found out there is no much difference if i lower density and lower Volume step length. Render time increase but i don't get much more detail.


I made a custom emission ramp to have more detail in the fire colors. Came out pretty good. I animated Max value to prevent overexposure at the beginning.


Here is a picture of the result i get from Octane Live Viewer. Render time is around 5 to 7 minutes with GTX 970 (1000 max samples)
Even if i increase max samples, grain go away but my detail problem remains.


And here is the result i get from Standard Renderer.
I placed lights to mimic the light of the Octane scene (i used a mix of HDRI Octane Sky and Octane lights). Obviously i was expecting a render difference, but my point is to show detail difference in the smoke.
Render time increase with time from 1 minute/image up to 15 minutes/image when there are a lot of details and transparent smoke


Is there something i can do to get more detail in the smoke ?
Thanks for your advice !

[Aleksei]

Hi, skotch. I had exactly the same problem. And it's all about Volume Step Length. Try to decrease it more. Set it to 0.1. If this won't help, then decrease even more. Once I've set it to 0,02 to get a decent result.

[skotch]

Hi, skotch. I had exactly the same problem. And it's all about Volume Step Length. Try to decrease it more. Set it to 0.1. If this won't help, then decrease even more. Once I've set it to 0,02 to get a decent result.

OK, i will try that but i'm afraid my render times will go insanely long !! It takes already 5 to 7 minutes per frame to render. I got 2 GTX 1080 but i can't use it and we're all expecting Octane compatibility to get the best out of it.
But i'm afraid i can't afford 30 minutes long per frame : i have a 200 frames long animation to render and multiple explosion in it. It would take months to render !!
What would your results had been regarding render times ?

[aoktar]

Hi, skotch. I had exactly the same problem. And it's all about Volume Step Length. Try to decrease it more. Set it to 0.1. If this won't help, then decrease even more. Once I've set it to 0,02 to get a decent result.

OK, i will try that but i'm afraid my render times will go insanely long !! It takes already 5 to 7 minutes per frame to render. I got 2 GTX 1080 but i can't use it and we're all expecting Octane compatibility to get the best out of it.
But i'm afraid i can't afford 30 minutes long per frame : i have a 200 frames long animation to render and multiple explosion in it. It would take months to render !!
What would your results had been regarding render times ?

There is not a straight logic as do step=0.02. It depend to voxel sizes. If you have voxel size=1 this means that you have 1 voxel on 1 unit. Forcing to use very small voxel steps just gives darker and longer results. I think you should solve the details by decreasing TFD simulation.

[skotch]

I made my simulation with voxel size at 1 and upres the simulation. I couldn't upres more, so i used the value of 2x.
Obviously, i could make a much longer and bigger simulation with voxel size at 0.5 but would i get better results ?

My point is : i get pretty good result with standard renderer and smoke comes out pretty good. I assume the simulation is OK since i already got the details i would like to have with standard rendering. They are already existing.
What would be the point to decrease TFD simulation (that would take longer to simulate and change drastically how the explosion would look like). Obviously, i would get finer details, but will they render ?