Cleaning up a volume render

   1351   5   1
User Avatar
Member
9 posts
Joined: Sept. 2018
Offline
Hello all

I have been spending a lot of time making nebulas and clouds lately.
I start with points and then convert those points into volumes or VDBs, but I keep encountering this "popping" issue.

I was hoping to get some ideas of how to solve it. I understand that it is caused by areas of low particle density, but I am really not sure how to solve that without having absolutely ludicrous amounts of points.

.hip file attached
Image Not Found




Edited by MostlyBees - Oct. 7, 2021 03:27:22

Attachments:
cloud02.png (1.7 MB)
Cloud01.png (1.5 MB)

User Avatar
Member
861 posts
Joined: Oct. 2008
Offline
If you use a scatter you can get a radius attribute with it. You can use that as a minimal size to convert to volume and are less like to have lone micropuffs of smoke.
--
Jobless
User Avatar
Member
9 posts
Joined: Sept. 2018
Offline
This is true, but I start to lose some detail on the rest of the volume when doing this.

I guess I was really hoping for a way to eliminate those stray particles. Or have then rasterize ignore them
User Avatar
Member
238 posts
Joined: Nov. 2013
Offline
First off all you might fall short on the point amount side. Give it some more! As long as you have enough RAM use it.
Second, in theory you will need a voxel per pixel to get rid of the stepping, usually that is not needed as you will have density overlapping so you can get away with less.
Than be aware that the Volume Shader in Redshift clamps density values at 1 on default.
http://www.sekowfx.com [www.sekowfx.com]
User Avatar
Member
861 posts
Joined: Oct. 2008
Offline
MostlyBees
This is true, but I start to lose some detail on the rest of the volume when doing this.

I guess I was really hoping for a way to eliminate those stray particles. Or have then rasterize ignore them

You can do some fancy lone-particle detection or use the particle fluid surface sop. Those kind of things never work that well in practice though so you need more points.
--
Jobless
User Avatar
Member
2 posts
Joined: Nov. 2008
Offline
I have had some success separating out more sparse edge points ( with nearpoints or pcfilter ) and using them to generate a mask which is used in the second input of vdbsmooth back on the main set of points, often this will smooth the edges but leave detail in the main volume.
  • Quick Links