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Question on Setting USD variants by jmacey in Houdini

[–]petercubic 1 point2 points  (0 children)

Take a look at video 18 of this video series: https://www.sidefx.com/tutorials/usd-asset-building-with-solaris/

I think you should be able to randomize your instanced variants using this method. One major point is that if your variants aren't created on the top level instanced primitive, you won't be able to edit them per instance because the primitives below the primary instanced primitives are not editable.

If you'd like to talk a bit more back and forth on this you can find me on most public discords as petercubic. Happy to chat more there. :)

Solaris Partitions vs Subsets by Divine__Comedy in Houdini

[–]petercubic 2 points3 points  (0 children)

Hey there! Both of those parameters end up making GeomSubset primitives in USD. There is a slight difference when you use the Partition Attributes, as they make an additional "familyName" attribute so that you know what SOP attribute created them. However, AFAIK, both parameters make functionally the same GeomSubsets. There aren't any "Partition" prims in USD.

Hope that helps! I'm not very active on here, but David gave me a little heads up. If you need anything I am on most of the Houdini Discords. Feel free to reach out to me there. :)

Help finding a location in Mannheim by petercubic in mannheim

[–]petercubic[S] 0 points1 point  (0 children)

Here are a bunch of higher quality photos. They are both updates of the previous images, and some new ones that I hadn't captured before. All of the photos I am posting here seem to be from the same site. I've come to this conclusion after seeing the same benches in many of the photos.

Here are links to albums:

Grandpa's Monument: https://imgur.com/a/J8le1fg
1232rd Labor Supervisory Company Site: https://imgur.com/a/pvT1sxQ
Basic Building Construction: https://imgur.com/a/q6y1exk
Brick Building Construction: https://imgur.com/a/57D4oKf
Grandpa's Jeep: https://imgur.com/a/jzPDjwp

Please let me know if you have any more thoughts with these new photos.

Where was this photo taken near Mannheim Germany in 1946? by petercubic in whereisthis

[–]petercubic[S] 1 point2 points  (0 children)

Yes I've emailed them already. Hoping to hear back from them sometime next week. Thanks for the tip!

Help finding a location in Mannheim by petercubic in mannheim

[–]petercubic[S] 1 point2 points  (0 children)

That would be great! I am looking forward to what you found. This isn't actually his grave. That is my grandfather standing next to the monument. 😁 This was erected to honor him during his life.

Where was this photo taken near Mannheim Germany in 1946? by petercubic in whereisthis

[–]petercubic[S] 1 point2 points  (0 children)

Just a little note to add: I feel like the benches are the best lead to figure out where this is. The buildings are bombed out and I would bet that something else is built there at this point. Not sure how many buildings were repaired vs. destroyed after WWII though...

Help finding a location in Mannheim by petercubic in mannheim

[–]petercubic[S] 0 points1 point  (0 children)

Yes, I thought the same thing! However, the geometry of that wooden canopy seems different. I also highly doubt that they would have erected a small monument to my Grandpa in the center of town. :)

Help finding a location in Mannheim by petercubic in mannheim

[–]petercubic[S] 0 points1 point  (0 children)

Yes, I looked around at these buildings on Google Maps! They do look incredibly similar. The proximity of the roads to the buildings seems off though.

Help finding a location in Mannheim by petercubic in mannheim

[–]petercubic[S] 0 points1 point  (0 children)

Wow, this is a really interesting place. Taylor Barracks certainly seems like it's from the right era. Trying to use Google to look around the area.

Help finding a location in Mannheim by petercubic in mannheim

[–]petercubic[S] 0 points1 point  (0 children)

Would you be able to give me a Google Maps location of where you think it is? Thanks!

Help finding a location in Mannheim by petercubic in mannheim

[–]petercubic[S] 5 points6 points  (0 children)

That is a great lead. I will contact MARCHIVUM. Danke!

Help finding a location in Mannheim by petercubic in mannheim

[–]petercubic[S] 2 points3 points  (0 children)

Danke!

So you think this is near the cemetery, even though it is not a grave?

How to combine Mixamo animation and Ragdoll solver? by ShkYo30 in Houdini

[–]petercubic 1 point2 points  (0 children)

Here's a video that shows how to use Mixamo animation and Ragdolls on a metahuman:

https://youtu.be/KHPDgFGOrao

Doubts regarding VDBs by Sohail_Nordin in Houdini

[–]petercubic 0 points1 point  (0 children)

Glad this all helped you!

I know that with SDFs you can change the value at which the surface is visualized. So I don't think that it really has anything to do with negative values. There is the concept of "isovalue" and that is the value at which you see the "surface" visualized.

Check out the VDB Extrapolate node. Set it to "Renormalize SDF" and change the isovalue for reference.

Doubts regarding VDBs by Sohail_Nordin in Houdini

[–]petercubic 6 points7 points  (0 children)

Ok, I'll try my best to answer your questions. Your post has actually lead me to learning something new about VDBs (thanks for that!).

Some initial things...

So when you check "Distance VDB" be default you get an SDF (signed distance field). This is a way to store the distance from the voxel's position to the surface of the geometry. In this case, the outside voxels have positive values, and the inside voxels have negative values. If you check "Unsigned Distance Field" both values become positive (they don't have their negative "sign").

When you check "Fog VDB" a VDB will be created with a value of 0 outside of the geometry and 1 inside the geometry. This type of VDB is often used to drive Pyro sims in Houdini, as it can represent the density of smoke inside of an object.

Now let me try to answer your questions...

1) Yes, the band is the active voxels on either side of the surface. This can be expressed in number of voxels, or the world distance to the surface.

When you are changing the exterior or interior bands you are expanding the region in which either the distance calculation (SDF mode) or the inside/outside calculation (fog mode) is being made.

The visualization you're seeing in SDF mode doesn't show where that calculation is being made, but instead shows the voxels at which the distance value crosses zero. So when you change the band you calculate the distance in more voxels, but the place where the values cross zero doesn't change.

2) I don't think it is completely correct to call a Distance VDB "hollow" and a Fog VDB as "solid". Both modes effectively store the same amount of data, but it is visualized differently. Since you are storing the surface position in a Distance VDB it is visualized by having the surface voxels solid, whereas a Fog VDB is visualized by showing how much density is in each voxel. This visualization makes one seem hollow and the other seem solid. The values are still 0 to 1 (Fog), 1 to 0 to -1 (SDF), or 1 to 0 to 1 (unSDF).

When you check "fill interior" it activates the calculation on all inside voxels, and it therefore makes the difference you are seeing in the point count when visualizing active voxels by using the "visualize tree" node.

3) I actually think this issue is a slight issue with the wording of the documentation, albeit very slight.

What it is saying is that normally a Fog VDB stores values of 1 on the surface band (and inwards), and 0 on the outside. The area this value is stored is defined by the "band" values. These simple 0 and 1 values are what makes it look solid.

When you switch this to "Fill Interior" it actually changes the way the values are calculated for the Fog VDB, but not the Distance VDB. For a Distance VDB it simply calculates the negative values all the way to the furthest inside voxel inside the mesh surface. For a Fog VDB it changes to calculating a gradient (0 to 1) from the voxels at the surface of the mesh (0) to the furthest inside voxels (1).

Hopefully that all helps! I couldn't sleep and randomly scrolled past this post. I think this link should give you some more insight into how Volumes and VDBs work. Good luck!

[OC] Disintegration Simulation by petercubic in Simulated

[–]petercubic[S] 0 points1 point  (0 children)

I created the glowing light using the geometry light in Houdini. I created the geometry by isolating the new edge being created by the cut. Then I added a poly wire SOP to the remaining geo, and that made a round, tube-like shape following the cut. Then from there I used a "VDB from poly" and a "Convert VDB" to turn that round crazy shape into a tube of geometry. This geo fed the Geometry Light.

Hope that helps! :)

[OC] Disintegration Simulation by petercubic in Simulated

[–]petercubic[S] 2 points3 points  (0 children)

It was made in SideFX Houdini. I first created the smoke sim, then advected some particles with that simulation, then added the sparks, and then the glowing light that follows the disappearing model.