RGB post sim

[joshclos]

This is a workflow question about the possibility of remapping output RGB data post sim. I'm simulating an explosion of temperature, smoke, and RGB. I'm using a red and green noise map producing the RGB output data, which I plan to use while rendering the smoke to produce variation in the color. The smoke could be rendered as red/green and colored in compositing (if fire and light emission wasn't involved) but I'm curious if it's possible to remap those RGB channel colors in the rendering settings post-sim from red/green to something else? Perhaps if there was a custom scalar channel, then those values could be used as a linear interpolation for the remapped color spectrum.

Or perhaps there is a better workflow for this. In the end I'm just aiming to get a natural variation in smoke color without re-simulating when those colors are changed.

Thanks!

[LarsSonparsson]

You can map Phoenix RGB channels using color correction node.
No need to resim anything.

Check the jpg attached.
In the zip file, there is Max material library (.mat file), where you can find that same node tree.

PHX_Smoke_RGB.zip

[Svetlin.Nikolov]

In addition, we have it in out TODO list to add a channel that does just what you said. Hopefully we can get there not long from now

[joshclos]

You can map Phoenix RGB channels using color correction node.
No need to resim anything.

Thanks for the tip! I gave it a shot and although this method makes sense, it doesn't seem to work in my scene. The smoke renders red/green when color is set to "RGB" as normal and when I set to "texture" and use this method for the texture, it seems to render a grey-ish color and does not appear to be properly masking. I'll keep testing a bit.

[joshclos]

In addition, we have it in out TODO list to add a channel that does just what you said. Hopefully we can get there not long from now

Fantastic! Thanks again!

[joshclos]

I'm not yet sure why but I've found that setting Smoke Color to be based on Texture and setting the texture to a PhoenixFDTexmap set to RGB will render differently than setting RGB directly through the smoke color method. In my case, it renders with the same colors but with some dark areas mixed into the smoke.

[LarsSonparsson]

I just did another test remapping colors using composite map and it works just fine.
Source color red and green turned to yellow and blue.

Remap_Smoke_Colors.zip

[joshclos]

I just did another test remapping colors using composite map and it works just fine.
Source color red and green turned to yellow and blue.

[ATTACH]n991508[/ATTACH]

Oh that's strange; It might be the version I'm on at this particular studio (3.04). I'll give it a shot at home with 3.1. Thanks again for the tip!

[Svetlin.Nikolov]

Ah yes - I know why this happens, will try to fix it in the next few days, thanks!

[Svetlin.Nikolov]

Hey, please check tomorrow's nightly (18 Apr) - this issue should be fixed and I also added a Sampler Type like in the Rendering rollout to the Grid Tex.

Cheers

[joshclos]

Thanks for fixing that so quickly! Very much appreciated

[LarsSonparsson]

Was this already fixed? Now I'm having this same problem, not getting pure rgb when using grid rgb as a texture.
Kinda looks like the rgb values from the grid texture are not coming thrue as pure colors.

Also, when doing this remapping colors using color correction nodes and composite map, the render time goes really high. Like 5 to 10 times slower? It wasn't that slow earlier, if I remember right.

Vray Next, Max 2019, Phoenix nightly from about two weeks ago.

I really would like to see a real solution for this. Some Phoenix color mix node maybe.

[Svetlin.Nikolov]

Hey,

If you can share a scene where the color is changed, and is possible one that gets much slower too so we can see what's wrong?

Otherwise, simulating indices and assigning colors post sim is important and hopefully we'll find some time between fixing issues to implement it

Cheers!

[LarsSonparsson]

It's a same scene. I'll send you later a Dropbox link with the scene and few aur frames.