Hello all, I'm getting some strange results when connecting my .obj file node to the Iso Offset node. If I were in Maya I would think the problem would be from the resolution of the container. But I'm fairly new to Houdini and am not sure if this is even an option.

First off, my ISO is not showing a fog-like pattern…more of a giant blob for my volume.

Eventually I want to make it an SDF Volume, but that yields strange results as well. (Pics below)


File and original mesh:


Results:

Construction:


SDF Volume:





I've attempted this on two versions of Houdini on two different machines. I don't have the other machine's info but this is my current one:

Houdini v13.0.437

Platform: windows-x86_64-cl15
Operating System: Windows 8 x64 (6.2.9200)
Number of Cores: 8
Physical Memory: 11.92 GB

OpenGL Vendor: NVIDIA Corporation
OpenGL Renderer: GeForce GTX 860M/PCIe/SSE2
OpenGL Version: 4.4.0
OpenGL Shading Language: 4.40 NVIDIA via Cg compiler
Viewport Render Version: GL 3.3
Detected: NVidia Consumer
2048 MB

My guess for the Fog volume is that Transparency is off (Display Options, Effects, Transparency).

The SDF is a volume, and uses a lit sprite at each voxel so that the volume resolution is easy to see. The previous polygonal display version didn't convey the resolution at all. If you'd like a polygonal surface, use a Convert SOP and adjust the U/V level of detail or divisions/span.

I think the SDF displays as a surface where the SDF value is 0 now, instead of showing the nearly useless display of the SDF values as each voxel (which would look like the inverse of the fog volume).

If you put a scatter on, then hook it up to an attribfromvolume to transfer the SDF values over, you'll see what those values actually are.

I could be wrong, but I think your fog volume looks crisp like that because your resolution is pretty high. The uniform sampling rate of 90 means that you're dividing the maximum dimension up into 90 voxels, so for a cube, that's a 90x90x90 grid for your sphere. If you reduce that to 20 or so, you'll see a much foggier fog volume.

Ben Andersen
I think the SDF displays as a surface where the SDF value is 0 now, instead of showing the nearly useless display of the SDF values as each voxel (which would look like the inverse of the fog volume).

If you put a scatter on, then hook it up to an attribfromvolume to transfer the SDF values over, you'll see what those values actually are.

I could be wrong, but I think your fog volume looks crisp like that because your resolution is pretty high. The uniform sampling rate of 90 means that you're dividing the maximum dimension up into 90 voxels, so for a cube, that's a 90x90x90 grid for your sphere. If you reduce that to 20 or so, you'll see a much foggier fog volume.

Sorry to correct you, but yes it's crisp because of the high resolution. But that does not have a direct correlation with how dense the result is. As you can see in the below image - It effects the crispness but not exactly the ‘foggy’ thing I'm looking for.

The scatter on SDF doesn't seem to help either.

twod
My guess for the Fog volume is that Transparency is off (Display Options, Effects, Transparency).

The SDF is a volume, and uses a lit sprite at each voxel so that the volume resolution is easy to see. The previous polygonal display version didn't convey the resolution at all. If you'd like a polygonal surface, use a Convert SOP and adjust the U/V level of detail or divisions/span.

I'm still learning this software so please bear with me:
Alright, the transparency seemed to resolve my fog volume, but I'm not too sure what you're talking about concerning the SDF.

I want a volume - however I'm unable to see the results of the SDF with the way the sprites are currently displaying. I'm trying to follow along with a digital tutors tutorial concerning using the SDF volume to calculate the depth.

This is the desired effect I'm going for:

SDF volumes don't display like the Digital Tutors one.

Perhaps the tutorial is quite old? Which Houdini version are they using.

MartybNz
SDF volumes don't display like the Digital Tutors one.

Perhaps the tutorial is quite old? Which Houdini version are they using.

hi i know this topic is a bit old, but i'm just learning this package and the tutorial i'm following shows the volume as foggy while mine is more crisp. my transparency is on, i'm currently in v14, and i believe the tutorial was made in v12. any help is appreciated.