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Found 199 results

  1. VDB and Noise in Houdini

    Hello Everyone, Welcome to VDB and noise in Houdini. This series will teach you how to generate a variety or organic and inorganic shapes and structures using VDB and the various procedural noise maps and textures available in Houdini. https://www.rohandalvi.net/vdb
  2. How to export vdb's in the right way

    Hello, I have a massive smoke simulation going on, and now I want to export this simulation in vdb's, to import them into a another 3d software (Blender). But when I click on the cache button or render to disk button, everything goes well, until frame 70 +-10 frames or so.. and then it stops because I am getting out or RAM. As I have 64 GB RAM, I would love if someone could explain me, how can I export the whole simulation, without decreasing the smoke division size... or smoke quality! I have tried to just export the density field, but then the smoke looks kinda low res and only if I am exporting ALL pyro fields, like: density, temperature, fuel, vel x, vel z, vel y.... and so on, then the smoke is high-res in Blender. But if I am exporting all fields, then it stops after frame 70 because of the RAM... is it possible to cut this simulation in parts and exporting them seperatly or somehow optimizing the fields or the pyro sim or vdb's so that I can export the whole simulation without any problems AND in high-res quality? Thanks for advance Daniel
  3. Hi everyone, I've an issue with vdb and i can"t find a way to solve this (so that's why i'm here haha) I'm working on a fluid simulation and i need to get the mesh into vdb to use it as collision surface. I'm trying to get a polygon mesh into vdb with the node vdb from polygone but there is holes and artefacts.. the issue is when i'm converting polygons into vdb with vdb from polygons there is a lot of holes into the vdb and I can't use it for my sim ( the particles goes through it). I think the problem comes from the mesh but I can't find what it is. (the mesh comes from Zbrush) I tried with a collision source node, same result as vdb from polygons. I can't find a way to get a clean vdb fron this mesh. So I wonder where those holes coming from and how can I fix it ? If someone have the solution, that will be great =D thanks a lot !
  4. Masking Volume Noise?

    hey folks. I've been following this amazing tutorial by Tim J but wanted to learn how to add attribute paint or another noise to use as a mask so only certain areas are effected by the volumetric noise I'm quite new to Houdini and have no idea! thanks in advance.
  5. Hey Guys, I came across a problem when simulation a vdb-mesh-transition and i was wondering what the proper workflow would be to replace my final mesh (the text in this case) with the text-mesh i was initially beginning with. I've read about point deform but this SOP didnt help me at all.. Im sure there must be a way to replace it in the right way but im just stuck like the total beginner i am.. I would appreciate any kind of help or direction very much!
  6. Flickering Liquid

    Hi there! I have this melting setup with a POP solver, basically scattering some points onto the original mesh and then melting then and meshing back everything again using "particlefluidsurface". So I have been trying to get rid of this flickering on the mesh, I have over 500k points and I also tried increasing the samples and playing with the particle separation in the "particlefluidsurface" I also tried using "vdbfromparticles" but its more or less the same result. I want to know if there is anything I can do to help reduce the flickering? Any help on this is much appreciated Thanks in advance untitled10.mp4
  7. Hello guys, I am desperate on this one! I want to fill with water this evolving shape that starts from nothing and expand like a flower. The idea is to make the fluid squirt out of it from the top (there is a hole on the top of the geo) but to start, I was thinking of filling the geo first. Maybe there are other ways to get the squirt going but I would like to fill the shape with liquid first. I am aware that I should use deforming VDB object for collision, I know the workflow but there is definitely something I don't know here. Whatever I do, the liquid goes through. I tried with a super high res VDB or even 8 substeps, nothing works. I suppose it will be easier if I attach the file so here it is test_ffluid_inside_growing_geo.hip Any idea? Thank you very much
  8. Hi there, As you can see on the video attached, my VDB is jumping from being fine to suddenly being almost gone, and then appearing again. What could be happening? The geometry that has been turned into a VDB has a fixed number of points. It was a curve fed into a revolveSOP, curve has been resampled to a fixed number and then that curve is scaled. Thats why the number of points is not changing. I am mentioning this because maybe it matters, but it probably doesn't. I don't know! If anyone knows how to fix this, that would be awesome!!! Thanks 2021-07-08 17-06-31.mkv2021-07-08 17-06-31.mkv
  9. dust Clump using VDB

    Any effective way to create this kind of dust. I used Cloud noise but doesn't seem to look preety well. any suggestion will be helpful. Thanks
  10. Hey wizards I have problems with exporting instanced scattered VDB clouds( they build a cloudscape). When i try to put a ROP geometry or a ROP alembic node at the end of the chain it doesnt work... My Goal is to export the "cloudscape" as a single vdb file to use that in 3ds max with vray for Production. Can anyone explain how to properly do that? Thanks in advance ;-) Cheers, Marcel
  11. Hello good people! So I have a few questions about VDB, mostly about things that I never cared about - until I had to. - Why are there translations on the fields of a VDB ? Most render engines do not seem to care, except for Vray. Vray apparently requires all those translatations to be the same for some reason - or else it will generate huge bounding boxes in Maya, and maybe even wrongly sample velocity. Resampling fields will "freeze" those transformations but I never had to do it with Arnold, RS, 3delight or Mantra. For extra giggle, putting a simple point wrangle with @P=0 apparently emulates how Vray see things. - Why can't I get rid of the "dopobject" and Cd attributes when saving to file ? The dopobject attribute is only added when importing the fields with a dopimport fields and not with an object merge. But with the dopimport it just keeps coming back from god knows where, and it makes no sense. - With Vray, am I stuck with having to use the same voxel size for all fields, including Vel, which can in turn creater HUGE files ? Doc indicates Vray can't handle vector fields and I can drop a vdb vector split, but there is nothing about voxel size. I have to accumulate tons of tricks to try and lower the file size. A 250mb VDB file with vel resampled to twice the voxel size can turn into a 1gb file with vel at the original voxel size - and because of how vray handles preview in the viewport, this is unbearable. Alternative is throwing the volume quality through the window to try and hope to reduce file size. I'll include a simple scene file with a few scenarios and oddities which just illustrate those quirks. As I said I usually have no issues but complaints from the Maya Vray departement upon long loading/refresh times ( even for mere 250mb files ) or motion blur not working forced me to approach things very differently... VDB_savingToFile.hip
  12. Exporting Pyro Simulation as VDB problem

    Hey all, I have set up a very big smoke simulation. And now I would want export it as VDB Files which I could import then into Blender. So far so good, but when I click in the file cache node on "Save to disk" it starts exporting it, but after like 60 or 70 frames its just stopping and Houdini is closing itself or there were an error which is saying "not enough memory" and some other stuff..... But this error isn't truth, because I have a external SSD where are nearly 500GB are left. After 60 frames (its only like 65 GB) its stopping... I dont know the issue but if someone has an idea, why its not exporting the whole frame range but just one part (like, 60 frames of 500 frames). It would be awesome if someone could help me... :/ My division size is 0.12 I have tried it with 0.09 and it has closed after 50 frames, now I have tried 0,12 and it has closed after 70 frames... I have tried to export it before on 0.2 I think, and It has worked without any problems. But when I like a better resolution then its crashing everytime...
  13. Hi everyone, I want to modify some very basic volume (created with a vdbfrompolygons) with a VOP network. I'm very new to this kind of volume manipulation and I'm having difficulties with the visualization of the volume in the viewport. When I decrease the voxel size of the VDB, a stepping appears in the volume viewport visualization. (The mantra render is ok) This bother me because I plan to do A LOT of manipulation in the VOP and it would pain me to do a render at every single modification of the network. Am I missing something obvious? It's hard to explain so I linked a picture that showcases what I mean with the .hip Thx for any help VoxelSizeProblem.hipnc
  14. Hi All, I'm planning a new workstation build and would like to know what hardware is used for VDB operations. E.g. does it use all cores or just a single one? More cores = faster operations? Is the amount of RAM a factor here or not really? RAM speed? I couldn't find any information about it and would like to make the appropriate choices which I can actually benefit from. Thanks!
  15. Masking VDB solver growth by Cd

    Hello friends. Perpetual Houdini n00b here. Have a question that I hope experienced users could help me with. In essenece - I'm trying to mask my solver growth areas by painting b/w mask on my geo. I am creating a solver growth for my geo. Converting a mesh into a VDB, sticking it into a Solver. Inside solver I calculate the gradient and curvature of the VDB, plug them into VolumeVOP, where I multiply them together and bind the output to gradient and pipe out to VDBAdvect. So all great, simple growth happening all over my mesh. I can mask it by plugging an extra noise into my multiply node. What I'd like to do though is to be able to mask it by painting custom b/w maps onto my geo prior to it going into solver. I can use attributePaint to the mask with on my Cd. But I have no idea how to access this Cd info inside my solver. I can add it as Surface Attribute to my VDB, but that messes everything up for some reason. I've attached the file, might be easiest to just see it in there instead of reading my explanation: Thanks for any suggestions the mighty ones! maskGrowth_v01.hiplc
  16. VDB level set or fog volume

    I have created a smoke sim using axiom solver and then created a vdb file from that. When I try to render that vdb using Renderman 23.5 i get the below error. Plugin error: impl_openvdb: Field function grid "temperature" in file "Z:/Library_rman/props/Mashal/vdb/Mashal_Fire_v1.0028.vdb" is not a level set or a fog volume, specify "temperature:levelset" or "temperature:fogvolume" to disambiguate [INFO python.RenderLog]: G29017 {ERROR} The "ImplicitFieldNew" function in Implicit plugin "impl_openvdb" returned NULL. My question is at the time of creating the vdb file how can i specify a level set or a fog volume so that Renderman can render the vdb?
  17. VDB Advect inside another VBD

    Hi! In the attached hip file there are a bunch of spheres generated using the pig head geo and connected to a solver with VDB advect. Is there a way I make these spheres grow inside the pig ahead so that when they grow to touch the surface of the pig ahead, they should just collide and deform? I tried converting the pig head to a vdb but I think it needs to be hollow from the inside for it work. Thank you so much for your help! VDB_advect.hiplc
  18. 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,
  19. 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.
  20. 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!
  21. 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
  22. 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?
  23. 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.
  24. 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.
  25. 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