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Found 182 results

  1. Hello, I need a way to set the value of a voxel of a hou.VDB with python. Do you know if there is an equivalent to the setVoxel() function used to the hou.Volume for the vdb ? Thanks in advance,
  2. how can i detect and delete small regions of a vdb sdf (which is changing every frame) - i want to delete anything smaller than a certain treshold.
  3. Hey all I have some low-ish resolution VDB dust clouds created in C4D with the TurbulenceFD plugin. These contain velocity channels. So far, I'm just not satisfied with the overall detail. What I've done to try and increase detail is convert the VDBs to Volumes, Volume Resample them, then use Volume Velocity to add some curl noise. It's looks OK, but by no means what you would call a true Up-res, that uses existing velocity channels to increase detail in turbulent areas... So that's the question really. How do I take a pre-calculated VDB (not dynamic at all) and give it a high-res makeover? Any pointers would be appreciated. Please be aware that the overall motion has been signed off, so all that I should be changing at this point is detail. I would just do the Up-res in TurbulenceFD, but it's buggy as hell and wont work. Every day I get closer to ditching C4D entirely. Thanks!
  4. Hello guys, So I have been trying to make a cloth collide with an animation sequence that is changing topology. I started with vellum and I hit a wall. Apparently, Vellum doesn't handle collisions with changing topology stuff. So I need to find a solution around this. My animation sequence is converted into a VDB and what else beside vellum can I use to handle the cloth? Any other ideas? Tx
  5. Hi guys I have a cloud volume render problem. I creat a instance VDB cloud and use ass to arnold render But in some places there appeared undesirable lines I will not have this error when I test in a single cloud and I only use standard_volume as the Shading I am also sure that there are no lights in these directions(2 arnold light) The horizontal or straight line in the image below is my problem I don't know how it is caused, is there any solution?
  6. Hi, I feel quite stupid, but does anyone know how I can make the surface vdb visible coming from a compressed fluid nde? The node contains the compressed points, a surface and a velocity vdb, but I cannot see them. I already tried the visibility SOP. Thanks for any hints. .... okay I found it. In the primitive SOP I can switch visibility for VDB's to isosurface what is exactly what I need.
  7. Clear VDB Cache after each frame

    Hi, I was wondering if you guys know a good way to clear caches after each frame so the available memory doesnt cause a crash, because its still full from the frame gefore.
  8. Volume shaping in dop network

    Hi guys! Recently I was asking for some advice on how to deform spherical parts of volume into different shapes (in my case skulls). And here is the best reply I've got: "You need a dop I/O node - target your dop network and then point it to your smoke object. Add an import field with the little plus button and import the field named "Pressure". This value is very small but if you use volume visualize nodes or volume vops you can fit the values to pull out the pressure range where these mushroom shapes occur. Once you know the range (usually somewhere around 0.02 to 0.00 for these shapes) you now have the correct mask range. You can now set "Pressure" as the control field in your disturbance tab on the pyro solver. Just make sure you use the correct range, then you can dial the strength of your disturbance applied in only the areas highlighted previously in your volume visualizer. One thing to note - if you want to identify them each you're going to need a sop solver. Once you have the pressure field isolated, you can convert the vdb to poly and use connectivity to seperate them out and then pack them to get a centroid for the specific mushroom. But you're going to want to blend the point position of that centroid over time as it may jitter or pop in and out of existence depending on the tightness of your isolation range. Once those points have a history they'll have velocity and direction you can use to orient your custom field that warps it into a skull or whatever." However, I'm stuck on the last step where I have to setup sop solver and feed the output back in a sim. I would be very grateful for any advice or more detailed instructions on how to set the last part up P.S. I've attached a basic setup file in case if needed sklsmk_test.hipnc geo_02.0001.bgeo.sc
  9. There's vel volume, but I can't see it with vdb analysis. Why not...? help me!
  10. Volumetric Temporal Deflicker 2.1 to Houdini 12.1 to 18.x Deflicker VDB/Fluids by analyzing areas of voxels, creating temporal volume gradients and use this info to interpolate those areas based on temporal volume falloff. It is very good at deflicker slow-motion fluids. Very easy 1 node solution to your flickering fluids or VDBs/volumes in general. Available on Orbolt (normal and studio versions) at https://www.orbolt.com/asset/RodTD::Rod_vdb_averaging Available on Gumroad at https://gum.co/deflicker Rod Tebisx | Senior Creature FX Technical Director at Framestore London Overview:
  11. Hi, I am importing an Alembic particle sequence from realflow. Shows up great in Houdini, no problems there. I want to 'mesh' it, I was thinking I would convert it to VDB and then to polys to have maximum control however the 'VDB from Particles' node is not taking the alembic particles (ie. nothing happens). Do I need to convert them to something else before? Am I approaching this completely wrong? Much obliged,
  12. 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
  13. 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
  14. 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...;)
  15. 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?
  16. 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??
  17. 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.
  18. 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?
  19. 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
  20. 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)
  21. 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
  22. 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?
  23. 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!
  24. 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
  25. 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
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