I create 4 scalar fields with values from 0 to 1.
Merge them together, name them Cd.x, Cd.y, Cd.z and density.
Why dont they show as colored volume ?
Why does the trail sop not find the Cd fields ?
Error message on trail node:
Cannot find any volumes of name Cd

Why does the trail sop not find the Cd fields ?

use Cd.* instead of Cd.

Why dont they show as colored volume ?

Only density is get displayed on viewport. So use “volumevisualization” sop and type “Cd.x” or “Cd.y” or “Cd.z” or “Cd.*” in Density Field.

Or use “Primitive” sop and turn on Adjust Visualization under Volumes tab.

Just found the error in the trail sop.
Had to write Cd.* instead of Cd.
But why the color volume does not show up in the viewport is a mystery to me…

PradeepBarua

Why dont they show as colored volume ?

Only density is get displayed on viewport. So use “volumevisualization” sop and type “Cd.x” or “Cd.y” or “Cd.z” or “Cd.*” in Density Field.

Yes, but the fourth node in the merge is a rename to density.
Shouldnt that be enough for the volume to show up in the viewport ?

Yes, but the fourth node in the merge is a rename to density.

Dear dulo, the file you posted doesn't have fourth node (density).

And one more thing, you are using Iso Offset to calculate SDF Volume (which is scalar) and naming it vel and without changing anything inside volumevop you're renaming those as Cd.x, Cd.y and Cd.z. That means all are the same. they hold exact same values.
Merge will return a vector volume with all the same three components.

The copied Fields are just for the example file. In the real scene all components come from a python sop.
You are right. I didn't post the latest example file with the fourth density component .. will post the file when I am at the office.