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ryew last won the day on May 25

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  1. Visible voxels in collision object in pyro sim

    In addition to Atom's excellent suggestions, double-check your viewport display options: in the Texturing tab, make sure you're not limiting the 3D Texture display resolution which can lead to blocky and low-res viewport visualization
  2. POP Curve Force

    No problem, happy to help. Fortunately, even if the behavior is not documented, some of the nodes in Houdini like the POP Curve Force will accept negative values and behave in a different but still predictable way - it's always worth tinkering a bit just to see what happens!
  3. POP Curve Force

    You can reverse the direction of your source curve with a Reverse SOP before using it in the sim and the green arrows of the curve force will show the change in direction, or you can just set the "Follow Scale" attribute to negative values in the Individual Forces tab however, the green arrows will not show a change in direction, although it will work.
  4. You're not far off, but to make life easier for you, my very first suggestion would be to move all your work closer to (or at) the (0,0,0) point on the grid and it will make the work much easier, especially for issues like this. For a quick and dirty way of doing this, just use -$CEX, -$CEY and -$CEZ respectively in your "Translate" attributes of the transform1 node to move the geo back to the origin from wherever it's at. This is related to the reason your visualization isn't appearing. The volume trail needs points within the area of the volume to trail from, but your grid is currently at (0,0,0) while your source geometry and volumes are many units below away from there (hence the first comment) - if you orient the grid to the YZ plane and move it to the area within your volume VOP output, you'll see the colored trails you're expecting.
  5. Popping / Shaking Artifacts with Whitewater

    Culling is at least a quick troubleshooting check to see if the issue is isolated at your collision surface. If you've already identified the density expressions as the source of the trouble as mentioned earlier in the thread, I'd suggest isolating a set of particles in the cache that is popping and trace their density values back through your expression logic.
  6. Popping / Shaking Artifacts with Whitewater

    It's why I was asking whether you are using a bubble<->whitewater logic in your network, to find out if this happening because certain particles are slowing below a particular threshold and flipping back and forth between states. I dealt with a situation like that previously and wound up culling particles within a certain threshold of the colliders (vdb dilation for grouping in a sopsolver post-sim and then deleting by id)
  7. Popping / Shaking Artifacts with Whitewater

    Is this only occurring where the whitewater is hitting your collider? Does your movie contain both bubbles and whitewater and is there a transition between the two? Hard to tell
  8. Track pyro simulation to a moving (Alembic) object

    If you mean attaching a cached simulation to a moving object, I've always had good results using a simple rivet at object level
  9. Sorry I don't have time to investigate your file, but have you compared your setup to John Lynch's H17 Advanced Vellum Workflows setup? https://www.sidefx.com/tutorials/advanced-vellum-workflows-h17-masterclass/ (apologies if you've already done this)
  10. Output locator

    If the Sphere type is a Primitive, try attaching an Add SOP set to "Delete Geometry but Keep The Points" and export just that point.
  11. DeepEXR to point cloud—how do I do this?

    Thanks for the contributing to the community knowledge pool by posting a solution, I'm sure this will help others in the future seeking a way to do this. Good on ya!
  12. Is the IntersectionStitch SOP what you're after? A quick test seems to create a vertex at the point where the branch touches the original/parent line.
  13. Mulitple Pop source emitters

    Perhaps try wiring in a POP Replicate node for secondary emission - it has an "emit by Attribute" field you can hook up to the attribute your original source is using to determine emission
  14. It's a tricky call, particularly with Houdini which releases fairly significant overhauls to their workflows year to year (Pyro in particular comes to mind, along with the move from cloth/FEM to vellum, etc.). The object-level rigging will be familiar to other packages like Maya, but from the major push, promotion and training that SideFX and others have been releasing, it does not appear that KineFX is going away any time soon. From the initial press releases/discussion, it sounds as though it has been in the works for a while at SideFX with the intention of it being the new go-to rigging technique - I'd say it's a safe bet to invest in learning it so you become more adept with the current/modern rigging techniques for Houdini rather than still using an older/deprecated system.
  15. It's hard to troubleshoot much without a scene to play with, but to be honest, vellum sounds like overkill for a shark swimming - if you just need the basic undulating motion of the tail and body twisting, why not try bend deformers? Unless your shark is doing complex motion - in which case you're better off just rigging it - it seems a more low-tech approach should do the trick without all the simulation headaches. Just my two cents - in my experience, it's unfortunately easy to overcomplicate things in Houdini