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Found 171 results

  1. Hey, I'm currently trying to get my skeleton object to interact with my vellum grains sim, I want it to start from sleeping and get awakened by the character animation pushing through it to imitate snow. Any help would be appreciated! If you could explain more, how/why this makes sense to Houdini will be even better to build my understanding for the program as I'm still a noob Snow_Crawl_2.hip
  2. For everone who dont know it already: detailed explanations about VDB, narrowband levelsets etc... from the founders at Dreamworks. Lot of explained examples in one file. A must have for everyone: Website: https://www.openvdb.org/download/ File: https://artifacts.aswf.io/io/aswf/openvdb/houdini_examples.hip/1.0.0/houdini_examples.hip-1.0.0.zip Dont miss to have a look, again, again... Cheers
  3. Hi Superior brains, as I approach modelling methodologies, I've turn my attention towards VDB's In the below example I've used a grid (but this would be an arbitrary shape Convex/concave "2Shape") with a noise pattern to create heights for a later extrude; I then convert to VDB to "cleanup the geo" My question: is it possible to directly manipulate the VDB via VEX to do something similar without having to go through the conversion process (poly to VDB) One reason behind this is the shape I wish to extrude can be fairly complex and dense thus making the conversion process slow, so perhaps adding voxels or extruding/expanding/manipulating voxels is possible in some way? ( VDB Wrangle?), feels like this is not possible but never hurts to ask... unless its physical...;)
  4. hi, I scattering points on a surface then I use vdb from particles on them, and finally convert the result into polygons, but I got an unwanted inner core geometry. How can I get rid of that procedurally?
  5. Hello, I made a comparison between Arnold and Mantra renderer about vdb motion blur. Mantra works like a charm, but anyone knows why Arnold volume motion blur looks like this??
  6. Dilate VDB

    Hi everyone, Is it possible to dilate a velocity vector field? The VDB Reshape SDF node only works on sdf fields. VDB Activate can expand but it only makes active voxels, I would like to expand the vel field values from the border of the field outward.
  7. Hi everyone, I'm trying to render vdbs with motion blur using mantra and arnold. With mantra it's working fine, but with arnold the motion blur won't be proper. I made a comparison. You can clearly see, something is not right. It became more obvious when I increased the velocity. The motion blur with mantra is excellent, but with arnold it became a mess. Do you have any idea what is happening here?
  8. Hi there, I want share for free my HDA for combine and export the cache of fluid from cluster system and convert it in VDB. Download here It's a open HDA so you can edit it if you want, please let me know if you do/did it and let me know if you use it in production. It's free, but a little donation is grateful Have a nice day Matteo video demo https://youtu.be/dLj2CaWam7Q
  9. Upres external simulation

    Is ist possible to make a simulation in embergen, export as vdb, import into houdini, and upres the simulation using gas upres? (you have density, temperature, vel, fuel and heat)
  10. I'm sure the answer to this will be something so easy, obvious, and profoundly stupid that my family and friends will all disavow having ever known me, but I'm stymied. I am using an animated noise to create a lumpy VDB fog field, which I convert to SDF and then use VDB Combine to cut out part of a hero model. I'm cutting it into two interlocking parts, using SDF Union Subtract for one side and SDF Union Intersection for the other, and I will subsequently assign a different material to each part. Originally I got it set up, no problem, with a standard AAnoise. I'm trying to get it set up with a periodic noise so I can loop it. The problem is that at the VDB combine stage, it doesn't subtract or intersect cleanly. You can tell something is happening, as there are little dotted lines on the resulting surface, and the occasional hole, but it's not cutting it out like I would like. I've tried different resolutions with the VDB from Polygons and that doesn't seem to make a difference. (I've actually run into this before, but I'll either rebuild the Volume VOP or fudge some numbers and it goes away. No such luck here.) What obvious, stupid thing am I doing wrong so that the VDB combine isn't working like I'm hoping? Thanks for help and forebearance! sdf_union_problems.hiplc
  11. I can save to bgeo.sc then once the simulation is cached I can read it with a file and convert to vdb, this takes longer (two steps). The initial sim with bgeo.sc is already using maximum RAM If I add a convert to vdb before the filecache, does this step take up more memory?
  12. I have a scene where I am dropping a bottle into a flip tank all at small scale. The issue im having is that I am getting a quite a large space/void between the bottle and the liquid. Im trying to reduce this and make the liquid hug the bottle more in the beginning and not blow outwards and make this gap. The setup is an RDB of the bottle falling using gravity from around 10cm into the tank, both the RDB and Flip have been slowed down to 0.025 in time scale. I tried a number of things like lowering the velocity scale, upping the subframes from 10 to 30 in the RDB and upping the subframes in the DOP network to 4/5, and changing the surface tension and viscosity, but it still happens. There is no problem with the collision guide and I dont have any sort of surface offset on that either, it matches the bottle perfectly. You can see in the attached screen grabs that the bottle has barely entered the fluid surface but has created a large void underneath it blowing out the liquid. This is the sort of splash im aiming for: https://www.youtube.com/watch?v=npAuLi1y5AA Dramatic but close and not blowing out internally too much. I know my bottle is a different shape to that reference but my sim seems way off and I cant seem to figure out how to lessen that gap. Any suggestions I would be very welcome as nothing I seem to try is making the gap any smaller. Thanks!
  13. Hi guys! I'm doing some tests with VDB and Point Deform SOP to recover original geometry point animation. The thing is I noticed when the VDB mesh result have a slightly different shape, the point deform SOP lose precision to move the new points. Is there any way to improve this? You can see what I'm talking in this basic example: If I raise the capture radius from 0.1 to 0.25 it works like 90% but only with this basic example, with a more complex element, my working scene, have some weird results displacing some parts of the geometry, and this happen if I change the capture radius or maximum points too. Maybe because I'm generating the hair / tentacles border with VDB dilate and the original geometry doesn't have those polygons? Is there a better technique to achieve this? I'm trying to use the VDB mesh because I want to generate motion vectors and rest attribute for procedural shading. I uploaded the basic scene if anyone can take a look. Thanks a lot! Bacteria VDB Mesh Example_v01.hiplc
  14. Displace surface by noise?

    Hello all, I know how to displace a surface, using the volume vop. VDB workflow. The displacement is generated by noise within the volume VOP. What I am trying to figure out now is how to have the displacement only on certain parts of the surface, only on certain parts of a sphere, for example. I can create noise on a surface, but how would I have that noise drive the displacement? So white is full displacement, black is none, for example? Thanks! T
  15. Transfer point color to vdb

    Hello, i am new with houdini and am trying to make a melt effect, i made it to transfer the uvs from the object to the melted object but now i want to transfer the vertex color from a ply file to the vdb but attribute transfer seams not working, Do you have any idea? I attach the file Thanks in advance Phaidonas melting.hip
  16. Hi; I would like to create a VDB from a polygon (that contains UV texture) and after some deformations (like anti-alias noise), I would like to convert it back to polygon. I tried to transfer UV attribute from volume to deformed polygon by turning the "Transfer Surface Attribut" option ON, in "ConvertVDB SOP", but it doesn't work in some parts of the final result. Thanks for helping. uv_Volume.hip
  17. Hello everyone, I have been attempting to figure out this problem on my own, however I have spent far too much time on it and would love some help if I could get it. It would be very much appreciated. I am attempting to create the effect seen in my first image, the very odd colored smoke. The second gif is what I currently have, which I would say is a good 70% of the final look for about the first third of the chunk of smoke. I need to create the next chunk of the effect, which is the larger more diffused, bigger turbulent smoke. I have been attempting various methods to achieve this. I have tried to use control fields on the current simulation. I don't think this is the best way because my GPU runs out of VRAM, and also I have less control than if I were to break it into multiple sims. I also tried copying the first VDB, clipping, transforming to the XMAX of the first VDB (where the next part of smoke should start), scaling, and retiming, which sort of worked from certain angles (not my camera) and I felt it was sloppy. So now I am wondering, what would be the best method to break this into 3 simulations? First part is fine, the tight, high frequency turbulence that I am happy with (happy to fine tune it later). Now second, the middle chunk of the bigger poofier part, and then finally the tail end. Maybe this could be done in 2 simulations. Maybe I would need 3. Would I want to source in from the same direction the first simulation is flowing outwards? I am not sure how to proceed efficiently and would really love some help! Thanks!
  18. VDB From particle fluid question

    Hey everybody, Hope you're all doing fine. I'm a Houdini rookie and got a question about the VDB from particles fluid node. Here is the case: I've got a particles emitter as a texture mapped on a distorted sphere. At the end of my POP node, when I plug a Particle Fluid Surface node, I get only the particles meshed and not the emitter. This is the result I want. But Particle fluid Surface result is poor. I would prefer using a VDB from particle fluid, but when I plug this node after my POP node, I get my emitter "meshed" in my VDB and not only my particles :(. Can anyone help please, getting mad on that s*"t since a few days now. Thank you very much <3 popfluid2.hip
  19. Hi. I'm rendering a clouds scene. Redshift log tells me I have 19 unique volumes, How can I instance those? I only have one volume in a geometry node and I copy pasted it another 18 times with different rotations. How can I make those an instance for houdini(redshift) Thank you.
  20. Flatten VDB sdf from multiple VDBs?

    Hi guys I'm currently working on a Particle collision situation with pre-sim RBD (converted to VDB SDF already). The SDF is a combination of multiple SDF moving within a timeframe, is there any way (or workaround) to flatten multiple vdb sdf into single VDB so POP static object can read properly (default volume collision did not support multiple SDF I think)? Anyway to flatten it? Thanks! Here's the VDB file. filecache2.v1.0040.bgeo.sc filecache2.v1.0040.bgeo.sc
  21. How do you combine 2 velocity fields?

    So, I am trying to advect some particles around a torus with a 'volume velocity from surface', thing is, once they get out of range of the torus they just kinda stay there. So I am trying to add another velocity field to push them back, however I have gotten awfully stuck on this. In the example I have a torus with velocity and a box with all velocities pointing inwards, so how do I best combine these two? Also Happy New Year to all! vel_test-01.hiplc
  22. Hello again, I need to turn a bunch of fairly low-quality objects (mostly intersections) from different sources I have no control over into watertight meshes. I tried using a vdbfrompolygons SOP followed by a convertvdb to turn the orignial mesh with all its intersections into a volume and then back into a clean mesh. This does work pretty well in some cases, unfortunately only as long as I keep a relatively large voxel size. When I increase the resolution in order to capture more of the original model's fidelity I run into a weird behaviour: when decreasing the voxel size below a certain value (in the current case 0.033) the object disintegrates and loses its solid shape, in most of the areas at least. The only way I found to counter this effect is to put in a VDBreshape node and dialate the whole thing a couple of notches before meshing it again. This, however, creates the next issue as it turnes the formally solid into a thin-walled mesh, as seen in the example on the right. Is there any way to resolve this? Why does the VDB suddenly flip from solid as expected to this strange partially solid, partially frame-like structure? If the mesh itself is unclear to the VDB algorithm, why does it work as long it is low-res? I've tried workarounds using grains or remesh or ISO offset but with pretty much the same result. I'm greatful for any advise! Felix vdb-resolution-issue.hipnc
  23. Hi Houdini friends, Does anyone know if there's a way to just load the metadata of a vdb file without loading the whole file? Trying some load settings on the File sop didn't achieve what I wanted, where "info" and "info bounding box" are both losing the detail attributes which are the metadata fields. Potential options are to use pyopenvdb or inlinecpp with the HDK openvdb classes (?), but maybe there's something I'm missing that is simpler? Thanks so much in advance! - Viola
  24. With fast moving collision geometry and FLIP, what are some things to try to stop fluid from passing thru your geometry? Things I've tried - increasing substeps (using 8 currently) - reducing particle separation (I'm at .01 currently) What else should I try?
  25. I've seen this setup in a few projects VDB from Polygons > create a Distance VDB (SDF) VDB Smooth Convert VDB > convert SDF to Fog Name > rename sdf group (created in Step#1) to density Why not skip SDF altogether and simply create a Fog VDB in Step#1?
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