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Found 16 results

  1. Combine VDB vectors

    Hi, I was wondering if anyone knows any method to combine velocity vectors of x number of VDBs with an average operation. With VDBCombine SOP either Add or Maximum operation will not give me the correct result because the add will put one vector on top of the other and the maximum will just keep the vector with the greater length. I can produce average using a volume wrangler and the avg() vex function but then I am limited to 4 volumes. cheers, C
  2. transfer Cd to vdb from particles

    I wondering if this is even possible? I'm animating points through a solver and then turning them into vdb's. I want to apply a random color on each particle. Everything seams to work until I convert to polygons. I tried to apply an attribute transfer after the convert but as you can see in the attached image the scale is off? If anyone can provide further assistance... It would be greatly appreciated! (I also attached a reduced file since I cannot send the actual scene) Thanks, vdb_HelpMe.01.hip
  3. Hi there, quite new to Houdini and I'm struggling to find documentation for something like this. I have a scene with a building where there are multiple fires starting at windows of varying sizes. This means I have different source volumes (fuel & temp, and a pump) for each window. I want to be able to render the pyro from each window separately and perhaps even have dynamic resizes for each source. The only way I could imagine doing this would be if it was possible to have multiple smoke object nodes that can reference different source volumes (the fuel & temp, and the pump). I saw that clustering exists but from what I understand it only accepts point sources? I am using a fluid source node building SDF from geometry to create the source volumes. What would be the best way of doing this? Thanks in advance and apologies if this has a very simple answer.
  4. Handling Large Volumes

    Hi, I have a box converted to a volume. Using a volume vop and noise I made some clouds. Here is the problem, I want a lot of clouds. So i go to my original box and scale it up. Since i scaled my box now i need to increase resolution. However, I cant increase the resolution high enough to get the clouds looking good when they are near the camera. I would need a ridiculously high amount of voxels to do that. Even 58 million voxels isn't high enough. Here is what I dont understand, I can do a similar thing in Maya. I can make non-dynamic texture based clouds. Here is what I like about Maya: When doing texture based clouds, I can use low resolution (small amount of voxels) but still get high quality clouds because the opacity of the volume is being textured by a high quality noise pattern. Look at the 2 viewport photos. Both the high resolution and low resolution (bottom two photos) produce basically the same render (top photo). How can I do some thing like that in houdini? In houdini, it seems like the resolution of the noise is dependent on the voxel resolution, where as in maya I can have low voxel resolution, but high quality noise and get good render. Any thoughts? Thanks
  5. Hey guys, sorry for my english There is a way in Houdini to detect the collision and have a organic style deformation without dynamics to avoid the intersection of the meshes? I have some geometry groups (tentacles based on curves) in a single object, so, I thinks is possible with volumes and a vex expression with if and else, but I'm not so good with vex, i'm still learning. So, using a foreach loop , maybe converting the mesh into volumes and use a scatter to have the surface and inside points to detect their position, how can I import in a wrangle the groups and their points info to create this type of action? I know the message but i don't know how to write it, some ideas? Thank you
  6. Turn vel streamers into usable curves

    I want to jack the streamer visualizations from my fluid source and use it to extrude shapes along. Is this doable? I want to do this because of how cleanly the streamer lines are distributed within a volume.
  7. Divergent noise

    As the title suggests. Im trying to achieve a diverging noise pattern in a cone shaped volume for a project I am working on. As far as I know, this effect is not possible but I have been proven wrong before. Can the example images I added be accomplished? Points or volumes, it doesnt matter, as long as I am able to have the noise diverge in the direction of the cone width. Any help would be appreciated. Thanks in advance.
  8. Hello everyone, This training is a series of small projects that will cover the process of creating a variety of volumetric effects in Houdini and rendering them using Octane. This training is primarily focused on modeling and rendering custom volume effects. Over the course of this training I'll cover a variety of effects which include building and rendering clouds, making a pyro shader and using the blackbody emission to control the pyro shader. We'll also build custom volume effects such as a gas flame and a nebula. Finally we'll take a look at building controllable volume lights and volume fog. NOTE: Additional lessons for Redshift and Mantra will be added to this training towards the end of October. (They will be available separately for download depending upon your renderer of choice. These parts will be charged separately.) For further details click on the link given below http://www.rohandalvi.net/volumetrics
  9. Grains to volume

    Hey guys, First post so go easy! But I was wondering if there was a way to convert the wet sand POP grains I've made into a volume by creating the vdb from the points generated by the sand? I've had a look around but can't really seem to find anything on it. I attached my .hip, its pretty straight forward, but the idea was to get the sphere to slice in half, but then recreate the geometry from the volume. Thanks split.hip
  10. If you have artifacts tune parameters in the display options>Texture
  11. Hey , I've been trying to use the pcwrite node inside a pyro shader to output a point cloud that will hopefully contain the shading values at render time. Ultimately Im hoping to use this point cloud to bake out a volume light and either use the point cloud or a volume created from it to shade my final renders. Ive got a scene ive tried to get the pcwrite to work with, but ive had no luck.. I've only seen it working with polygon geometry and not yet in a volume. Ive tried combing the forums but haven't had any luck. Any information or guidance would be great. Cheers!
  12. deforming volumes with cached geometry

    Hey guys, I have an alembic file of an animated deforming creature from maya. I am converting it into a VDB volume and applying noise via vop sop. I created a rest.x rest.y rest.z volume to compute the volume rest fields for animation. Now the problem is, after I create these volume rest fields I need to then deform the volume rest fields to match the alembic animation so my rest field will deform along with the geometry and the noise will stick to it without any slipping At the most basic level I can manually keyframe a xform sop, but the noise slips when there is deformation; i.e. this only works with translation or rotation So is there any way to somehow transfer the deformation of the alembic animation over to the volume? I tried transferring density to points, deforming via lattice and then transferring back, but this caused a huge loss of detail/unpredictable results. I also tried transferring volume attributes, along with a thousand other things, with no luck. I posted an example file. Thanks! volume_deform.rar
  13. Alembic to VDB issue

    Hey guys, I am having an issue that I can't figure out. I have an imported alembic file from maya and am converting it to a VDB using the cloud tool. However if I change the resolution of the cloud object to anything other than the default, most of the model disappears and I am left with only tiny clumps. If I remap the density it starts to reappear, but when rendered it looks transparent. I have tried a bunch of different solutions, including every kind of world space scale trick I can think of, cleaned and checked every aspect of the model, and still I always get unpredictable and random results. Sometimes plugging in different combinations of noise and switching between models and switching back yields completely different results. Is this a VDB problem, a problem with my model, with alembic? Any help would be greatly appreciated. I attached a simple scene with my alembic file Thank you! alembic_cloud.rar
  14. Multiresolution VDB grids

    Don't know if this is more of a VDB issue rather a Houdini issue. One thinks you should be able to create a relatively low resolution VDB for a large model, then combine it with VDB grids for areas of high detail. Good example, patching in a flip sims into a large body of water. You could have a relatively low rez SDF grid for the main body of water, then generate high rez SDFs for each of your flip simulations, do a VDB combine using 'min', and they all combine nicely. As far as I can tell, the output is set to a single voxel size, multiresolution is not an option. I know that VDB scales so well, this should be a non-issue for most cases. But I'm definitely hitting RAM walls with the resolution detail requirements. Multires grids are a perfect solution to this problem.
  15. Hello everyone, First of all a big thank you to all the people that have uploaded Pyro solver and shading tips. I am currently learning/exploring Pyro and have some questions. - I want to make an object explode. So I am trying to find the proper way to source the pyro solver. I am thinking first of all to do the RBD sim, fracture the object, put the appropriate forces etc. Then there are two options: Should I use the RBD sim to source the pyro or make another geometry like a sphere and try to simulate the energy that caused the explosion? One thing that comes to my mind is to use the velocity values of the fractured objects that fly away. - I cant find any comprehensive guide on proper volume render AOVs for compositing (RGB light setup etc.) Any info on both subjects is highly appreciated. Thank you in advance. George p.s. to make myself more clear I made a quick setup for fun: just did a pyro sim with a sphere source and on top I copied the sphere and fractured it. http://www.frameworks.gr/explosivo.mp4
  16. Pixar is promoting their new speed improvements when rendering volumes in RenderMan 17, so I was wondering if anyone has done an apples to apples comparison vs. mantra. I haven't done any controlled comparisons yet, but anecdotal evidence at work so far suggests it is still behind mantra. Can anyone share any more info regarding speed/memory tests? -Jon