In a smoke sim, does Houdini require the value range for the density attribute to be between 0 and 1, or can this be higher than 1? I ask because in one tutorial these values are deliberately set within this range. I am not sure if this is because it must be kept withing this range to use in Houdini smoke sims or for another reason. i.e. can density value be higher than 1 or does Houdini expect a normalised 0-1 range? I have

It can be higher

AFAIK Houdini doesn't use any specific unit for density so it's a bit arbitrary and often times further multiplied in the shader

On the other hand there may be an advantage of establishing some personal consistency for the sake of reusability

In my opinion it's worse with temperature which is not in any units either, which makes it difficult to be really consistent across sim and shading

Thanks for clarifying that tamte.

Typically, there is no need to control density in the 0-1 range in smoke simulations. This requirement may occur with some custom fields.

But sometimes I will control the density or some other custom fields in the sop to 0-1 according to my own needs, such as when I need to use volume sampling.

Hope this helps you.

Thanks