VDB Voxel

[7enith]

Hello,

will vray for Modo support the vdb voxel? Its very useful since its probably the only option to get smoke simulations in there. Or maybe you guys even bring PhoenixFD to Modo

all the best
christian

[vlado]

We will be working on VDB support, yes.

Best regards,
Vlado

[vladimir.nedev]

We will add the V-Ray Volume Grid that is in V-Ray for Max and Maya. Probably won't support the VDB voxel and MODO "Volume" item directly, as it will take me too much time to figure out how to translate them properly to V-Ray.
I am working on the Volume Grid UI at the moment, hopefully I can add an initial version in the nightly builds before the holidays. Here are some test renders, one uses a VDB file, the other a Phoenix cache generated in Phoenix for 3ds Max:




Greetings,
Vladimir Nedev

[7enith]

We will add the V-Ray Volume Grid that is in V-Ray for Max and Maya. Probably won't support the VDB voxel and MODO "Volume" item directly, as it will take me too much time to figure out how to translate them properly to V-Ray.
I am working on the Volume Grid UI at the moment, hopefully I can add an initial version in the nightly builds before the holidays. Here are some test renders, one uses a VDB file, the other a Phoenix cache generated in Phoenix for 3ds Max:

[ATTACH=CONFIG]27392[/ATTACH]
[ATTACH=CONFIG]27393[/ATTACH]

Greetings,
Vladimir Nedev

that looks pretty good!! I really hope the foundry will add a proper fluid system to Modo! But until then I´ll happily use your Volume Grid once I convinced my boss to buy a Vray to Modo license

all the best
christian

[vladimir.nedev]

The volume grid is in today's nightly builds ( 2015.12.16 ). I still haven't tested it on Mac OS X though.
I will give it a try there, and then post some information on how to use it, some limitations and caveats. It's still a work in progress.

Greetings,
Vladimir Nedev

[vladimir.nedev]

A simple animation I rendered as a test.

https://youtu.be/Ow1mlwY6hz8

Greetings,
Vladimir Nedev

[vladimir.nedev]

It turns out the initial Mac OS X build from today ( 2015.12.16 ) didn't have the OpenVDB and Field3D libraries.
This is fixed in this build : vray_beta_30102_modo_mavericks_x64_DONGLE_LIC_2655 0.rar

Here is a possible workflow with the V-Ray Volume Grid and some current limitations :

1. Create the V-Ray Volume Grid from the Item List -> Add Item -> V-Ray Geometry

2. Choose a cache file in the V-Ray Volume Grid tab under Input

If you choose the file using the "Browse..." button, some automatic things will happen

a) if the file has a frame number, it will be replaced with #### which denotes the current frame

b) if the file is OpenVDB or Field3D, its grids will be auto-remapped to the Phoenix grids (Smoke, Temperature, Fuel, Velocity and Color)
You can see this remapping in the V-Ray Volume Grid Channels tab under 3rd Party Channel Mappings. You can also modify it from there.

3. Different fluid simulators output smoke/temperature/fuel in different units, so the range of values between them differ.

Once you choose a particular grid in one of the Incandescence / Diffuse / Opacity Input drop-downs in the main V-Ray Volume Grid tab,
you can use the Guess input offset and scale from input grid button, which will use the selected grid's min and max values to setup Input Offset and Input Scale.
Input Offset and Input Scale define the range of grid values that the gradients remap. If you have Input Offset to 300 for example, and Input Scale set to 500,
this means that the left-most point of the gradient will be used to remap grid cells that have a value of 300, while the right-most point will be used for grid cells with a value of 800 ( 300 + 500 ).

4. The gradient controls don't have very suitable default values, see my original images for a basic idea how you should set them up.

5. If you have issues with the quality of the rendering check the options in the V-Ray Volume Grid Adv. tab.

Most important are the Rend. Step (%), Shadow Step(%), Sampler Type.

6. Area lights seem to slow down the volume grid shading quite a bit. Not sure if I forgot to set some parameter somewhere.

So you may want to disable Environment Importance Sampling from the Render item -> V-Ray GI tab since it implicitly creates a Dome Light, especially while doing test renders.

7. Some stuff is currently not updated in RT, so you will have to restart it to see the correct result:

- changing Input Cache File ( this can actually cause crashes especially on Mac OS X)
- changing Render Mode
- changing the current MODO time ( you can work-around this by setting Animation Control in Time Bend Controls to Frame Index and then changing the Frame Index channel without restarting RT)
- changing Enable Lighting from the V-Ray Volume Grid Adv. tab
- changing any of the channels in the V-Ray Volume Grid Channels tab

The V-Ray Volume Grid help for V-Ray for Maya can also be useful : http://docs.chaosgroup.com/display/V...VRayVolumeGrid

I am on vacation from tomorrow until 2016.01.04 , so I won't be able to fix any issues until then, but hopefully the volume grid is usable at its current state.

Greetings,
Vladimir Nedev