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Found 110 results

  1. VEX in Volume Wrangle

    Hi all, I'm trying to write some vex in a volume wrangle but I'm really struggling atm, not sure if the problem is the syntax or my inexperience with voxels. I have a volume which I set up with random densities and then, in the next step, the density of a voxel should be affected by the surrounding voxels. I've done the first step but can't figure out how to access the "closest neighbour voxels". I guess they have some sort of index but can't figure out which voxel has which index or if I should access them by their position. Tried to use the function volumeindex() to find index and volumesample() to take a sample from a position but both only returns 0 so I'm obviously doing something wrong. I wrote it like this: vector pos = {2, 2, 2}; float temp = volumeindex(0, "@A", pos); printf("%f\n", temp); @A += temp; It doesn't seem to matter what position I use for the vector pos, the functions always return 0 either way. So if someone knows anything about this it would be great volumeRandom.hipnc
  2. We are happy to announce an unique opportunity to experience a live Masterclass with Entagma's Manuel & Moritz. http://everythingprocedural.com/ https://www.facebook.com/everythingprocedural https://twitter.com/everythingproc >>> Preceding the Everything Procedural conference, NHTV will host a two-day SideFX Houdini Masterclass by Entagma's Manuel & Moritz. This is a unique opportunity to learn, meet and work with the best mentors in the field. Day 1: PBD Techiques - Manuel Casasola Merkle Although PBDs are called "grains" in Houdini, they offer far more possibilities than just simulating your average sand castle. Wires, Cloth, even fluids can be efficiently simulated using PBDs. Not only that but they come in handy when it comes to numerical problems such as surface packing. Manuel will give an in-depth look into how to set up multiple production proven PBD setups, covering not only the logic behind Houdini's grain system but also how it works under the hood and how to take advantage of its architecture. Day 2: Volume Techniques - Moritz Schwind One of the most fascinating aspects of Houdini is the deep implementation of volumes into the software. Be it geometry creation, simulation or shading & rendering - volumes can play a vital role in your projects. With tools such as VDBs and openCL at your disposal in Houdini, you gain control over what (if not revolutionize) is going to change your workflow. Moritz walks you through his favourite techniques when using volumes in Houdini, including advanced topics such as volume procedurals and working with volumes in openCL. The Masterclass will be a two-day event (both 9:00-17:00) and take place on Monday April 23rd and Tuesday April 24th. We have only limited places. >>>
  3. Gradient Falloff Volume

    Hi everyone, I am dabbling with volumes recently and I wish to know how can I have a fall-off of volume, gradiently? (see image attached). I have zero to minimal knowledge of volume vop. Forum Users talk about volume sample and volume gradient when I search on forums regarding this issue. **Additional Info-- Better still if I can control, say, point A is densest and point B is thinnest.** Thank you in advance.
  4. Hey! Is this normal behavior? I am trying to visualize the velocity field of my pyro simulation, but the position of the plane on the y axis keeps shifting up and down which makes some frames look completely different because it is looking at a different y position of the sim. It makes it difficult to see if my velocity field is simulating correctly. Look at the two photos below, it seems like the velocity drastically changed, but its actually because the slice moved upwards and it is showing the velocity of a higher part of the sim. Is this normal? Thanks
  5. Hello fellow scientists,I am currently working on a shot where I want to render out an indoor-explosion over about 50 frames. Now since I can't get my mantra render-times below 20 minutes (in FHD) I had hoped to render the volume in redshift more quickly because I have had good experiences with rendering just density in RS.The problem comes up as soon as I start to use emission with redshift. I start to get very weird boxes of emission around the edges of my volume (it seems to be like 16 cubed boxes of voxels reminding me of compression.) - screen attached. Screenshot_50 has about the look I want to achieve, but with this weird halo. When I amp up the emission, the boxes become apparent.Not sure if I tried switching to VDB to render, but I'm not hopeful that would change much.Has anyone come across this issue before?Attached is also my hipfile with the way I set up my render and one cached frame so you don't have to sim again. (Including my approach to an indoor-explosion for anyone who might learn something from that - please do!)I would really appreciate any thoughts on this. (And if my decision to move away from mantra in this case is actually remotely sensible - I'm really unsure.)Thanks,Martin Grenade_RnD_v20.hip
  6. Volume mixing with VolumeVop

    Hello ! I made an explosion and I try to make it loop with Timeshift and volume mix nodes, Sadly I feels its too limited as the fading between the two volumes are quite obvious. Is there a way to mix volumes with a VolumeVOP ? The idea is to add simple 3d noise as the volume fade in and out. Thanks a lots
  7. How can I render animated trail like these from my simulation? Be able to add material to these and do other stuff too if possible. Thank you so much for your help. I succeeded to see these trails in my Dop Import but it shows nothing in renderer (example pic from internet) http://www.sidefx.com/docs/houdini/images/visualizers/volume_trails.png Thank you so so much
  8. Crowd and Volume collisions

    I have baked agents loop for crowds. I need some hints how to generate smoke, dust on the each crowd agents footsteps for walk, run on a dusty terrain adaption in compositing for example, at what level does it have to be done?
  9. Hello! Normally I always find the answers to any Houdini issue that comes into my way, but this time I decided to finally communicate my current issue! My first question ever in odforce hehe So well... I'm doing my graduation film, and is about a shepherd that transforms sheep wool into clouds for doing rain! After some previous phase of research, we decided to give the wool a "cloudy" look, more than giving clouds a "wooly" look. So I'm using volumes to recreate the sheep wool! Thanks to various threads made by countless users here in odforce, I was able to: *Create interesting noise density values for the VDBs, hence giving a "wooly" look to the volume. I wanted "puffy" looking volumes, so I scattered particles in the sheep mesh, and created VDB out of them. *Transfer spatial transformation data from an alembic animated mesh to a volume, this way helping me to maintain the overall noise that will have otherwise been calculated at each frame if I moved the mesh I used for the VDB creation directly. *Deform the noised volume through a volume lattice technique by Juraj Tomori and Matt Estela (I'm enormously grateful for having shared their hip files!!! They saved my life). The volume will keep its noise while being deformed by box, itself deformed by an edit or a bend node. Up until now! Everything is going well! The only issue I have is.... How can I assign the point cache information of an animated lattice in Maya to a box with the same dimensions and subdivisions in Houdini? I thought that maybe an attribute transfer I could transfer the P data.. But I don't know if I need some vex to grab the position of every point in the lattice an assign them to a new matrix... I have no idea.. But knowing how to do this will be excelent! This way any lattice deformations the animators will do in Maya will be directly fetched to the box in Houdini! Any ideas?
  10. Hi, Can anyone shed some light on how to use the gasBlendDensity microsolver? I haven't seen a working example of it anywhere. Here is an example scene with the fields setup, trying to blend between 2 volumes. gas_diffuse_blend_example.hip Cheers
  11. Hello ! Is there a simple way to transfer velocity attributes from a volume to another ? Or create velocity from scratch ? Thanks !
  12. Delete by Volume

    Hey! I have a sphere, then delete by volume. I have the bounding volume animated. Here is the problem: once the primitive leaves the volume it reappears. How can I keep it permanently deleted, even if the volume leaves that primitive? Thanks delete_volume.hipnc
  13. I can't figure out how to get the output created by the "Sky Rig" shelf tool from the Cloud FX shelf to render with Redshift. I have no similar issue with the volume created by the "Cloud Rig" tool, although both seem to me like they create a VDB volume with a channel called "density" (which is what I've tried to render in Redshift with an "RS Volume" shader, which again works just fine with the kind of volume that "Cloud Rig" creates). What am I missing?
  14. I am adding the uniformvolume material to my geometry to get simple and quick fog. Works like a charm (the green example at the top). Why I get the enable dispmap warning, I do not know - displacement is not enabled. Now, if I plug in some more detailed colour information (bottom sample), the fog disappears completely. What am I doing wrong here? Plugging into the colour input is just one example. It seems this material doesn't like to get any inputs. That can't be right?
  15. Hi all, I have a big pyro simulation where I am clustering the simulation with multiple bounding boxes. The problem I have is that each primitive bounding box has its own density, vel , temperature fields separate. Here is a screenshot of how that looks: Is there a way to combine all those volumes and create one field for each?? Thank you in advance!
  16. Hello, now when I am loading VDB volumes with File SOP it sometime takes some time, especially with big volumes stored on network. I was wondering whether it is possible to load only specified volumes from a VDB file, for example to load only heat, to keep loading times slower. This would save a lot of time in situations where I am blasting all other volumes which I do not need directly after File node. I quickly checked docs and found that it is possible to firstly read the header to find out information about stored VDBs and then to load needed volume (in Reading and modifying a grid section). Any ideas if it is supported right now in Houdini implementation / or if there are any plans to add this? Juraj
  17. Hey guys... So what I'm trying to do here is to make the skull go through the cloud and make it look somewhat natural but I can't get the effect I want I tried it two different ways and both give me crazy advection.... (also I don't know if is just a view port thing or the light, or the sim, but the cloud also looks like id flickering) Anyway I'll attach the file and if anyone can give me some advice on how to do it better or if maybe I'm doing something the wrong way or missing anything I would really appreciate it! Thanks! movingCloud_09.hipnc

    Hello everyone! I have a problem with my alpha, when I render my clouds separately (what i don't render is in matte shading) I end up with weird alphas in compositing. Do some of you have the same problem, or is there something obvious I'm missing? Thank you!
  19. In Houdini, can I colorize a volume (either VDB of Houdini volume) based on the voxel location in space? E.g.if I have a cube-shaped volume, can I color its quadrants differently?
  20. Volume density from texture?

    Hello magicians, I saw a great image by Lee Griggs the other day and I tried to replicate, here is the original effect He did it with Arnold (i think in maya), by projecting a texture into a volume density, here is some explanation https://support.solidangle.com/pages/viewpage.action?pageId=55710284 I didnt know how to project a texture into density, so I projected a texture, the deleted by color and converted that into vdb > fog, but that way I don't get any depth, any ideas? I've read about a rest field that does something like UV on volumes but cant figure out how Here are my attempts: Hip file attached, Cheers! volnoise3.hip
  21. Volume Velocity to Mesh?

    Hey guys, I'm growing some objects using volumes (scene is attached) and I'd like to have motion blur on the moving/growing areas. I do have some velocity on the volume, in order to control it's growing direction, but i have no idea on how to transfer it to the mesh itself. here's how the setup looks like: Thx Volume.Growth.Velocity.v1a.hiplc
  22. Hello everybody, Here is my first post so I will present myself in few words. I'm Thomas Renault, FX teacher in ESMA school (France). I'm using Houdini since two years now and I enjoy it more and more everyday. First of all I would like to thanks all the community and SideFx team for feeding us continually with documentation and tutorials. That's the first time I post in odforce because I uselly search and find my answer without requesting anyone. Here is my problem : I tryed to render volume in renderman (21,4) for Houdini (16) with motion blur without sucess. I found this on pixar documentation : https://rmanwiki.pixar.com/display/REN/PxrVolume but no fonctionnal blur at all in houdini... Any advice ?
  23. Y ramp volume vop

    Hey, I am trying to use a volume vop to create a ramp that controls the y density of my volume, so I can have it fade off. If you look at the volume vop in my scene, you can see that it kinda works. There seems to be a problem with the fall off. Any suggestions? clouds4.hiplc
  24. Properly Sourcing Volumes in Pyro

    Hi, How do I properly source a volume I already created, and use that for pyro? I made a cloud using the cloud node, and added some noise. I am trying to use it as a source for my pyro sim to have dynamic clouds. For some reason, at frame 1 there is no density. Then the volume fills up. Shouldn't the first frame just be the cloud already there? I am trying to learn how to source vdb/volumes that I make and use it as a source for pyro. Thanks clouds.hipnc
  25. Does anyone know why volumes have this artifacting that is visible when the grid is behind the volume? You don't really see it if you have something else behind the volume. See photos.