Caching in VDB nearly freezing 3dsMax

[BeneZ]

Hi Georgi,

many thanks for the explanations.
1. I will check it out next time - it means now, I have keep "simple smoke" but enable "modulate".

2. yes I followed an older forum post, where was suggested just to copy cache_converter.exe into the same folder like the files.

the manual is unfortunately not telling much, where exactly to put the files and how the converter appication is targeted
in the command line example I can't find something written, that tells where to find the folder of cache_converter AND the other folder of the aur-files.

So it would need to destinations specified:
- where is cache_converter.exe
- where are the ".aur"-files to find
please let me know how to do this.
If I navigate the command panel to the folder with the "aur"-files, then how do I tell where to find the cache_converter.exe?

4. okay that's new to me, another unknown hidden rule
It means I must never scale the simulator? You can see plenty tutorials, where they do it...
It means I have always to do it with the input fields?

Thanks again

[BeneZ]

1. ...

In your case the Smoke color is being shaded by the RGB channel, but in the scene the RGB is colored only where the emission of the fluid happens and the empty space in the grid has a black RGB.
So the renders turned black because the RGB at the walls of the sim is black.

One thing I still don't understand:
I did not choose "RGB", I set it to "Texture" and the attached Texture is a checker, and so it should be visible.

Or does it mean, that "Texture" means here the RGB channel (so it should be called RGB in my opinion) and the connected "Texture" right below is something different, which only comes into play as multiplier, when I activate "modulate"?

Attached the screenshot I mean...
Cheers

[Svetlin.Nikolov]

I did not see the scene so Georgi will be able to tell more, but I wanted to drop in on something else.

Note that if you choose Based On Texture, then this is enough to replace the smoke opacity with a texture entirely. You don't need to check Modulate in that case. You need Modulate when Based On is set to anything else but Texture, e.g. Smoke or Speed, and you want to multiply that by a texture. In the screenshot you have attached, you are just basically telling the shader that the opacity texture should get multiplied by itself.

Cheers!

[georgi.zhekov]

One thing I still don't understand:
I did not choose "RGB", I set it to "Texture" and the attached Texture is a checker, and so it should be visible.

Or does it mean, that "Texture" means here the RGB channel (so it should be called RGB in my opinion) and the connected "Texture" right below is something different, which only comes into play as multiplier, when I activate "modulate"?

Attached the screenshot I mean...
Cheers

Yes, you have the Smoke opacity set to Texture, but the color of the smoke is set to RGB.

In your scene - the RGB channel will color the smoke emitted from the teapot based on the texture you have set in the source. The rest of the cells, where there is no smoke emitted will use the default RGB value - which is black.
The easiest way to check how the RGB channel looks like is to turn off the GPU preview checkbox in the Preview rollout and enabled the RGB voxel preview.

When you set the opacity to be based on Texture - the opacity of the smoke will be coming only from the Texture itself as Svetlin mentioned above.

In you case the texture will make opaque cells that have no smoke and these cells have black RGB color.

As for the cache converter - the cache_converter.exe doesn't need to be in the same folder as the cache files you will be converting - they are independent. You can have the exe in one folder, the source files in another one and the final destination in a third place.
In the default location of the cache converter there are two dll files - openvdbio_phx.dll and field3dio_phx.dll - these need to be in the same folder as the cache_converter.exe so that the files can be read and converted properly to VDB and f3d format.

As for the scaling - you can scale it, but the scale needs to be uniform in all dimensions. This is relevant if you wish to simulate the scaled simulator.
If you have finished simming and will only render the cache files, feel free to change the scale as you see fit.

[Svetlin.Nikolov]

Btw, maybe you are looking at some tutorial that only used the simulator to load already simulated caches for rendering? Otherwise scaling the simulator for doing simulation is not gonna end good. Can you link such tutorials here? I wonder why they are working out at all...

[BeneZ]

Many thanks, I will test it again I'm next time in 2 weeks back at this topic.

The cache_converter worked now and very fast! (so if that works there is no reason anymore to waste time with any VDB simulation).
(I did not check the conversion result, but I have it anyway to redo it with an undistorted simulator.)

I left the "exe" it in its original folder and addressed the full pathes of source and destination files.