2.3 GPU Volume Grid


Using the V-Ray Volume Grid on the GPU allows you to render volumetric effects such as fire and smoke, extremely fast.

  • Go to Create Panel > V-Ray > and create a “VolumeGrid”
  • Click somewhere close to the origin and pick one of the Cloud cache files from the “Asset” folder
  • Start IPR
  • You can control the color, opacity and other properties of the smoke through the rendering options of the “VolumeGrid”
  • In “Smoke Color” rollout, change the “Constant color” to white
  • In “Smoke Opacity” rollout, reduce the “Simple Smoke Opacity” quite a bit
  • You can also reduce the “External Scatter Mult” to make the cloud a bit more contrasty
  • Next you can experiment with the preview settings  
  • They are going to affect only the viewport appearance and not the rendering result of the cache
  • When creating multiple copies you might want to reduce the preview voxels number for better viewport performance (Details Reduction)
  • You can switch to the render camera and populate the sky with some clouds

 

 

 

 

2.3.1 Volume Grid Texture Steps


With V-Ray Next Update 1, you can also use the Volume Grid without needing to load in cache files. Instead, you can use a 3D Texture to create a volume, such as non-uniform fog, or textured details in the fog.

  • Go to Create Panel > V-Ray and create a “VolumeGrid”.
  • When prompted to load a cache file, click cancel.
  • Next with the volume grid selected, go to the Modify Panel> Rendering > Volumetric Options.
  • Expand the “Smoke Opacity” tab and set it to be based on a texture.
  • Click on the texture slot and select a 3D texture - such as noise.
  • Start IPR.
  • Create an instance of the noise texture in the material editor to modify it.
  • Decrease its size to something around 6.
  • To add more contrast, you can also adjust the high and low thresholds of the noise texture.
  • Finally set the noise type to fractal and its levels to 10.
  • Stop the IPR.
  • Next go to the “Layer Explorer” and make the “Geometry” layer visible.
  • With the volume grid selected go to the main toolbar and right click on the scale icon.
  • Set the scale to 25000%.
  • Now switch to the render camera.
  • Change the proportions of the volume grid from its "Grid" section.
  • You can set it to roughly match the size of the green rectangle visible in the top viewport.
  • Click on the "Decrease Resolution" button a few times until you end up with a few million cells.
  • Once again start IPR.
  • Now let’s change the color of the volume grid.
  • From “Volumetric Options” set the color to be based on a texture.
  • Drag and drop a copy of the texture used for the opacity in the color texture slot.
  • Adjust its colors and continue tweaking the parameters of both noise textures until you are happy with the result.