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Found 154 results

  1. 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
  2. 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.
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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?
  8. 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?
  9. Heightfields

    Hey there! Okay so I have got a grasp of how a heightfield works but what I am trying to do is confusing me. I have the sole of a shoe and on one surface I want it to have the heightfield on. How do I merge the heightfield with the surface? I have used the project node but I still get the square. I also used attributes from volume and then a point wrangle to transfer the height to the Y position but It affects the whole of the geo. I need help! Mountain_Duality_Sole.hip
  10. VDB velocity half circle?

    Hi! Houdini beginner here. I have multiple curves that spin around that's being converted to VDB for smoke sim, but I'm getting this weird half-circle from its velocity. It almost looks like it's being clipped. How do I fix this? Thank you! vel_zero_on_z-axis.hipnc
  11. I have a smoke master cache at the origin created in houdini (vdb). I am positioning this cache in the world (attaching to anim) using copy to points with orientation. I would like to cache out only the point (with position and orientation attribute) Import that point in Maya, and instance the master cache vdb directly from disk with the correct position and orientation. Could you please suggest me how to achieve this? Context. This master is used across an entire sequence. For every shot is placed and re-cached out in position. This is very inefficient, both time and disk storage wise. An instancing system would be a true game changer.
  12. Smoke Sim- vel not coming through?

    Hi! Houdini beginner here. I created a custom velocity using pointVOP and added onto VDB surface attrib point.v as vel. When I middle-mouse click, it shows that vel exists. I have it scaled higher than 0 on the volume source in the DOP network and set "Add" for the operation option, but it makes no difference in the smoke sim. There's supposed to be a noise pattern in the velocity, but it's only taking into account of gravity. If I disable the gravity, nothing happens to the volume (the volume surface get steppier? but it doesn't push the smoke or anything). There's also a custom temperature going into DOP, but that one works fine. So I think I missed a step somewhere when bringing the velocity into the DOP network.....What am I missing? Thank you!!
  13. Hi everyone, Basically what I am trying to do is simple but haven't been able to find a way that works. I have an animated object and I converted it into a VDB to eventually turn it into a cloud. However, once the object is converted into VDB and it moves, the VDB starts moving through the object in World Scale and flickers , is there any way I can have the VDB stick to the object? Thank you!!
  14. Hi, Im new to arnold for Houdini and want to know if there is a way to directly specify a vdb volume in the string path instead of a file on disc. for e.g.: I tried: /obj/cloud/OUT op:`opfullpath("/obj/cloud/OUT")` op: /obj/cloud/OUT ( without any luck) thnx for the help!
  15. Hey! I don't really know how to properly describe my problem. I have created a cloud vdb from polygon geometry. Everything works and looks fine but when I imported it into c4d for rendering I noticed I only got a "real" volume export in some areas. I tried to export and re-import my vdb in houdini, it looks perfectly fine. But as soon as I create a Points from Volume sop I get the same issue again. It seems like there are only certain areas where "real" volume is created. I have no idea why this is happening and need a cloud effect for a project asap. Would really appreciate ANY help.
  16. Hi there, I have a scene that has some noisy ground fog that helps establish the atmosphere of the scene. I am working with a single frame of vdb that was created with some volume noise. It's simple but it works great for stills! I am trying to come up with a good way of advecting it, or at least applying some form of subtle animation that will make it appear more dynamic in motion. It's fog, so it doesn't need to be anything too crazy. Curious what your solutions would be to this problem! Cheers
  17. Hey guys, I'm having some issues with a FLIP collision, seems my VDB collider boundaries are affecting the sim, anyone knows what can be causing this? I'm using static object + static solver with a proxy volume as collider. Thanks!
  18. Hello I am trying to mix/combine the density and colour of two different VDBs into one VDB in Houdini (image 1, file attached). For the most part, this is working as desired but there are two main issues: 1. Pink fuzzy edges around the blue VDB - How do I get nice clean edges where the blue VDB smoothly fades out to transparent? (image 2) 2. Blue VDB does not go all the way to the border of the pink VDB - How do I make sure both VDBs finish on the same outside border? (image 3) I have tried adjusting the voxel size, changing the set up of the VDBs (ie. the exterior/interior band voxels, fill interior) but I can't seem to get it working the way I want. Can anyone please help me? I have only been learning Houdini for just over a month so example files would be helpful. Thank you! Mix VDBs.hip
  19. Hi, A simple question but I can't seem to get the answer. I need to convert a sphere primitive to a volume, when I do this with a VDBfromPoly instead of the VDB showing up as a perfect sphere I get this low res sphere similar to what you would get with a low frequency poly sphere (see screenshot) Is there something to tweak to get a perfect sphere, or is there a better way to to convert from a primitive straight to a volume? P.S. The reason I need to do this is because Im copying a few hundred thousand spheres to points and if I try to do this with poly spheres houdini crashes always.. only way I seem to be able to do it is by keeping the original sphere a primitive. Thanks!
  20. Volumetric Temporal Deflicker 2.1

    Digital asset download at Orbolt! Enjoy https://www.orbolt.com/asset/RodTD::Rod_vdb_averaging
  21. more advanced vdb to spheres?

    Hi Houdini community, I`m wondering, what is a good way to fill a geo with spheres, just like VDB to Spheres SOP, but with greater control and without intersection. At my studio, we just finished a project, involving close ups of beer foam (bubbles in it). My problem with the node mentioned earlier is that I can not choose a distribution ratio between the pscales, like a ramp would allow me. Now I`m trying to come up a solution just for fun. My first thought would be to scatter in a fog, and than relax is after generating pscale, but that pushes out the points from the original geo to much. Anybody got an idea? Thanks for reading this.
  22. Looping rain drips on windows

    Hi there, I've been following this excellent tutorial on creating streaks of rain across windows: https://www.youtube.com/watch?v=AwsYhKy1K5g It's working well and i've made a few adjustments to fit with the rest of my scene, but there are a few things I was hoping someone might be kind enough to help me with: 1. The tutorial author uses an expression to offset a resample node to create the animation of the drops falling - how would I adapt this expression so that I can create a seamless loop? 2. More simple: the drops created by this method are fully sphereical, I need them to be flat on the edge that touches the window - how do I use a vdb volume to cut the whole thing so the window facing side is flat? 3. Just trying to get the static drops to be a bit more random in size and guessing at the expression, currently @pscale = (rand(@ptnum)*(0.15)+2.2) -1.20; - i'm just trying to pick a random float between 0.1 and 1.2 I've attached my scene file, any help is very appreciated. window4.mp4 raindrops_001.hip
  23. Hello houdini guys, Im trying to simulate physarum polycephalum growth, but unfortunately it has some small issues. I would like to ask U on 3 main questions, if u will able to help me with any of them, it will be very helpful for me! 1. I have problem with VDB convertion as U can see on the picture, the distributed mesh (from wire extrude) is broken and VDB looks like particles. I dont know how to fix that. 2. In my file (I marked it with red network box) the small vein system of my slime mold, and I would like to connect it to the growing solver, but I dont know how. Basically I need this small veins with same growing properties like the big one have. 3. And last one is is possible to make the slime mold more "fat" on the edge? I dot hnow how to select this part of mesh? :/ ( like onreference picture) Thank U guys for any advices! Im looking forward! Bye! Physarum.hip
  24. post process volumes

    Hey I'm looking into some volume post processing, I need to be very art directable on a volume after the sim so basically what I need to do is define areas where I need to increase density for instance, or decrease it. which is the best way?
  25. Procedural rocks carved in vdb

    Hey guys, I'm trying to understand how to make procedural rocks carved in volumes using the technique exposed at Siggraph by Saber Jlassi. You can find the video here Hi approach is to use a combination of worley and aanoise in VOP. The result should look similar to this image. I joined the image of his vop network too. I didn't manage to reproduce what he is doing, been trying all day. Is there anyone here who would be up for giving it a go with me ? Any help would be very much appreciated. Chris
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