Bakes the light fields together before raymarching through them. This remaps the values in the VDBs before starting to raymarch. The node iterates over the density field and light field VDBs (the combination of Diffuse Color and Emission Color). Quality decreases and the output can appear more blocky when the VDB contains tiles. Turn this off if you want higher quality output.

When off, the node can take longer to run since the OpenCL kernel must iterate over four uncombined VDBs simultaneously, which requires more shader registers.

This parameter internally generates a new VDB to store the combined light fields. It uses the Density field’s topology as this VDB’s topology, so a density input is always required. To render a pure Emission field, wire the same layer into the density and emission inputs and set Density Scale to 0.

Determines the amount of diffuse light at any point. The node finds the eight voxels that surround the sample locations in the Density field and multiply these by the corresponding voxels in the Diffuse field. The node linearly interpolates the eight voxel values at the sample location. This has higher accuracy but can be slow since the node remaps each field eight times. This can cause a difference near the boundaries of the active region of the density field since you might expect regions with zero density to not contribute any color to the final raster.

When off, the node samples the two fields at the given sample location and multiplies the interpolated values together. This is faster but has lower accuracy.

Turn this on when there are visual artifacts in the output or the density changes very quickly from inactive (0) to a high density. This option may not make a difference for rasterizing pyro simulations because density often varies smoothly, so turn this off for better performance.

For example, consider sampling halfway between a voxel with nonzero density and an inactive density voxel. In the color field there may be some non-black color where the density field is nonzero and a black background color. If you sample halfway between these two voxels, the interpolated density is nonzero but the interpolated color is darker because it’s halfway between black and the active voxel’s color. This results in the boundary of the active region looking darker than it should. When this option is turned on, the node first multiplies the density and diffuse fields and the inactive voxels with a black color don’t contribute to the final output because they have zero density.

The length of ray slices. This is the expected distance between samples when samples are jittered.

Used to prevent the OpenCL kernel from running forever or timing out. You shouldn’t need to change the 4096 value unless rastering a very deep volume.

The transmittance of the accumulated portion of the ray after which to stop raymarching. A value of -1 turns this off and forces raymarching to continue until the ray exits the volume’s bounding box, though there should be no difference in the output between 0 and -1.

This is an optimisation for when a very dense region of the volume is encountered, where almost none of the light from behind this region reaches the camera so you can stop raymarching early to save time. Due to a rounding error, it’s possible for the accumulated transmittance to reach 0 despite this not being physically possible, and this is seen when rasterizing very dense volumes.

Makes the sample location jittering depend on time.

The amount by which to jitter sample locations. When 0, sample locations are always at the centre of ray slices. When 1, sample locations can be drawn from anywhere along their respective ray slice. There is never more than one sample drawn per ray slice.

The amount by which to jitter ray slice locations. This is a single offset applied to each view ray, not per sample. When 0, the start of ray slice #0 coincides with the ray origin. When 1, the start of ray slice #0 varies from backward and forward along the ray by half the step length.