Phoenix rendering issue from 2.2 to 3.1

[Badbullet]

So, I'm experiencing an issue with an old file that was done with Phoenix 2.2 I believe. When opened up with Phoenix 3.1, the atmospherics and materials with opacity (no refraction or reflections), looks like it is additive in the colors instead of subtractive. Channels used are smoke, and RGB set in separate PHXSources, but one Phoenix sim.

Or is it possible there's a rendering difference because of using VRay 2.4 to 3.6? I also noticed that the lights don't work they way they used to either. If I tell a light (omnis with VRayShadows) to only include the Phoenix sim, it casts shadows from the geometry even though it should exclude it, so Phoenix renders black.

If anyone has ran into this issue, any way to fix it? Am I missing a setting that has been added between old and new versions of either Phoenix or VRay that adds the colors together instead of rendering one color in front of the other?

Attached is the render done this morning, and one frame grabbed from the old animation. You can see in the current render how the yellow is added to the blue, no matter which one is in front. Edit, the yellow and blue also ignore the diffuse and opacity of the objects in front of them, they should be more greenish in appearance as those materials are not 100% transparent.

[Svetlin.Nikolov]

I'm afraid there is such a huge number of changes between Phoenix 2.2, Phoenix 3.0 and the latest Phoenix 3.12 that even though we've added conversion code for most of the changes we did, some of the settings cannot be converted directly so you will have to manually re-adjust the settings.

[Badbullet]

Switching to Atmospheric Geometry seems to have fixed the additive issue so far, renders slower though. But as a benefit it now shows up in the MultiMatteElement.

[Svetlin.Nikolov]

Indeed, in geometry mode you will get render elements, but at the cost of much lower render speed.

[Badbullet]

Turns out it was the transparent material used on the object that the simulation flows through. Previously, I could use a fog color to kind of cheat the color of the opacity (no refraction) on that material, and deepen the color of the smoke the further it was from the surface. Previous version of VRay and Phoenix had no issue rendering this with Volumetric smoke. Now, it causes issues with the transparency of the smoke. Setting the opacity to Stochastic fixed some of the issues, but created whole other issues and dramatically increased the render time. So it could be VRay, or Phoenix and some changes to how opacity is treated with the fog color? Volumetric Geometry renders fine when using the fog color this way, it just takes too long to render, and also doesn't work with the Fade Out setting or Cutter Geometry. So I guess my best bet will be to tweak the opacity and diffuse of the transparent geometry until it is kind of close to the original look. Unfortunately it doesn't change the color of the smoke flowing through like the fog setting did, it really added some depth without using GI, and rendered fast. Hopefully the client won't notice too much.