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Found 129 results

  1. Hey guys, I have been having troubles with extracting transforms from an incoming alembic and apply it its vdb. My guess is, that you extract transforms using transform matrices in VOPs and apply it to the position of the vdb. But I don't know how. Can somebody help me with it please? -bf
  2. I'm emitting smoke with colors. After adding and creating dop fields import with density, vel and Cd channel for rendering the colors are not visible in the render. When I'm visualizing them as color channel everything works fine. How can I make volume colors visible in Redshift render?
  3. I have a main volume that I want to render. however In that volume I would love to be able to merge other volumes into it and use those volumes as extra image planes. This means that my second volume should NOT show up in my beauty pass, but be available as an AOV. is this possible? Right now I have it setup so I render the second volume separately, but I wonder if the other thing could be done?
  4. Subdivide / interpolate voxel?

    Hi guys, I'm working on some pyro simulations which require dense fluid look. I have to crush the density remapping to achieve the dense look. But the banding issue appears. So I'm thinking is it possible to subdivide each voxel to 8 small voxels and interpolate the density value? Thanks!
  5. "Foreword" - MULMO

    Hi guys, Here is a new MULMO piece of work, fx all done using Houdini, enjoy! ludo
  6. Hi guys. I am trying to utilize my point attribs in a volume. how can I: - set the volume color (shade the volume) using my point color? - when volume is created, get it to read already set density values on the points. (volume rasterize). attached is an example file. cheers colortovolume.hiplc
  7. Hi I've been playing around with the wdas data set cloud and I've noticed that we houdini users (who are not lucky enough to have access to shaders dveloped by giant companies) lack an overall dense (almost pyroclastic) cloud shader that shows the distinct features of puffy cumulus clouds. After a through searching both in web and odforce i've seen that a few people also inquired on the same subject but it was inconclusive. I've decided to use this post as an idea dump to possibly implement a new shader or track your opinion on the subject. During the searching i've realized that distinct features of dense clouds are achievable by either using a very high number of internal light bounces or by faking them. I have seen that dark edges are the most prominent feature of the dense clouds since the other effects as transmittance and high forward scattering are already studied and implemented in shaders. To assess the current state of volume rendering other then mantra i've done a couple tests with several renderers in maya and also tried the new terragen 4.2. The most beautiful (simulating a real cloud light) is the hyperion render. Terragen 4 clouds are also very realistic and detailed (http://terragen4.com/first-look/). Arnold seems to be the best commercial option out there and is very good in giving the edge darkening but fails at details in dark areas (which is highly visible in hyperion) but i think these areas can be compansated with additional ligths. Redshift render is blazing fast but no where near the realism. In houdini i have used pbr with 50 volume limit, 5x5 samples, volume quality at 2 with a standart volume cloud shader. I have just started to see dark edges but even rendering a very small portion of 1920x1080 image took me about 10 minutes ( 2xE5-2680 v3, 48 cores total) . For speed comparison, redshift was the fastest with a couple minutes, arnold took about 10 minutes, terragen is said to be around an hour for a very heavy cumulus cloud. No information about hyperion but since wdas has a 50.000 core farm it shouldn't be a problem. Mantra was the worst with a projected couple hours of total render. Below are the sources i found for future reference for myself Oliver also asked about a cloud shader and Mike Lyndon says he has implemented a shader before (https://forums.odforce.net/topic/17900-cloud-shader/) . This is the most prominent one and is the one i will be implementing. The thesis of Antoine Bouthors that Mike says he has implemented (http://evasion.imag.fr/~Antoine.Bouthors/research/phd/thesis/thesis.pdf) . Beautiful mie scattering solution by Matt and the base for my shader (http://mattebb.com/weblog/rendering-clouds-with-the-mie-phase-function/) Odforce user Andrea was also interested in such topic and has some ideas in it (https://forums.odforce.net/topic/24831-cloud-shader/) Modelling aspect of clouds (https://forums.odforce.net/topic/12923-pyroclastic-noise-demystified/?page=2) Siggraph presentation by Magnus Wrenninge (http://magnuswrenninge.com/content/pubs/VolumetricMethodsInVisualEffects2010.pdf) Realtime clouds for horizon zero dawn by guerilla games. realtime but has really nice implementations (horizon zero dawn real time clouds) A hefty paper from Hyperion developer Yining Karl Li (https://blog.yiningkarlli.com/2017/07/spectral-and-decomposition-tracking.html) With the directions i gathered from Mike Lyndon's post i have started implementing the photon map approach. I have already implemented a henyey-greenstein phase function and added the contribution by radiance photons. Now i will try to implement the ideas presented in the thesis of Antoine, with high focus on cumulus cloud rendering (ch. 7). Attached is the current state of shader (cloud_shader.rar) I am also interested in GLSL implementations for viewport and cloud modelling tools but i guess this post wil be mostly about a shop type implementation. anyway here is a simple glsl implementation work and i am open to every feedback https://forums.odforce.net/topic/32197-glsl-pipeline-in-houdini/?tab=comments#comment-190945 I am definitely not an expert on this subject, so all input, ideas, criticsm, and source is welcomed. Thank you. Hyperion Render (wdas_cloud_hyperion_render.png is Copyright 2017 Disney Enterprises, Inc. and are licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License ) Terragen 4 Render terragen_4_render.tif Houdini Pbr Render (the little part on top took 10 minutes to render so i left it unfinished) Arnold Render Redshift Render
  8. best way to add fields to volume

    Hi, Lets say I create a box node than iso offset and set the name to density. I have a volume with density. What if I want to add a temperature field? I know I can duplicate the iso offset, change the name to temperature, then merge the two volumes. Isn't there a better to add other fields? Perhaps using name sop or VDB node? Thanks
  9. Hi guys! I am working on a project that needs a spirit moving through a scene, it needs to be like flowing smoke with a glowing light effect so that if reflects on objects in the scene. I cant work out how to emit light from the smoke and move with the animation, i have been playing with both volume lights and geometry lights but i cant get either to move with the animation, they both stay at where the animation is on frame 1. I have tried selecting the volume and creating a volume light from that, and also using the original animated geometry before it was turned into a volume and making a geometry light from that, but neither use the animation. Can anyone suggest what i am missing or doing wrong? Or way to get the smoke to emit light and use the animation to move? I have attached a r&d scene file and a play-blast of my problem as it stands at the moment, any help would be really appreciated! smokeLight_001.hipnc smokeLight.mp4 smokeLight_001.hipnc
  10. Collision object in Pyro sim

    Hi everyone, I am working on a smoke simulation and i have imported my collision object with source volume into my Pyro sim. No matter how much I increase the smoke divisions as well as reducing the voxel size on colliding geometry I still get jagged edges when smoke interacts with it. I have attached a screen capture here to make it more clear. Is there any way to smooth the jagged edges or am I missing something in the process? Any tips would be greatly appreciated!
  11. I am doing pcopen in cvex to to render points as volume but for some reason I am not able to scale the density as much as I want. It looks like it is clamping the density values and doesn't allow me to go higher. When I use smaller IFD bounds this problem fixes itself but also it cuts my overall object. Also vex volume procedural doesn't seem to work with new mat context. Thanks for the solutions, Alican
  12. Smoke Effect skin

    Hi Everyone I was wondering if someone knows how I can create this effect I have just done a simple smoke simulation, but I do not know how to make the inside: also, if anyone knows, I am trying to create this object with the exterior like the purple surface, but the inside to look like this: ANY HELP WOULD BE APPRECIATED
  13. Smoke Effect skin

    Hi Everyone I was wondering if someone knows how I can create this effect I have just done a simple smoke simulation, but I do not know how to make the inside: also, if anyone knows, I am trying to create this object with the exterior like the purple surface, but the inside to look like this: ANY HELP WOULD BE APPRECIATED
  14. I'm trying to render out a volume inside of a clear object and running into an odd materials glitch. To test I have created a box with a default glass principle shader and a VDB volume of the same box shrunk down inside the box which I have colored blue. Rendering with Mantra, if the volume is inside glass box, it loses all color, but outside keeps it. There is one other issue. I really want the volume to filter the light to color, so the shadow/rays coming out of the volume should be roughly the same color as the volume, as opposed to being black. volumeTest.hipnc
  15. Hello All, I'm newer to Houdini, and working to jump into setting up some simple/fast solutions for wrapping particles around a mesh. Not sticking to the mesh, but flowing over. I'm a professional Nuke compositor with general experience in Maya, so will understand most terminology, but certainly completely new to Houdini, so open to all suggestions and breakdown's of the principles. The end goal is to drive a curl noise vortex up in Y, and place geo within the field that the noise will wrap and flow around. I have attached my test HIP file. I've been trying to combine this tutorial's use of the cross product and XYZ distance, with the VDB setup from Entagma's Curl Noise tutorial. Other than there being a good possibility I'm on the completely wrong path for this type of effect, it seems I may be confused on properly using the cross product in the VolumeVOP. The attached file doesn't touch properly adding or multiplying in the curl noise, because I want to correct my issue with the field to begin. Thank you all for your time, patience and help. My Best, Josh curl_noise_trailsTest_003.hipnc
  16. Can't render particles as volume.

    Hi everyone. I am trying to render Houdini particles as volume. Volume appears in the viewport but cant be seen in the render. I created white water using shelf tool in another new scene and copied the network into my file. I am clueless about the problem. Please help. Thank you.
  17. Interior Fluid Shader

    Hey wizards! I have a challenge I need help solving. I'm doing a flip sim where I have to mix two different fluids together, I.E. water and lets say molten aluminum. Clearly these two fluids need 2 different shaders, but when doing a sim you'd want one one mesh to keep everything clean without gaps or ips. I've already created a single shader driven by surface attributes to get the two different materials to work on the same mesh. There's only one massive, glaring issue with this method. You don't get any of your interior attributes back from your particles when using a mesh. The many solutions I've tried all fall short including using volume representations of the interior fluid, this is because a volume cannot receive lighting information that surfaces can I.E spec, refraction, SSS, etc. One idea that I haven't been able to fully explore, due to my lack of shading knowledge, is the way that ocean shaders use particle and volume data to create the deep ocean looks that Houdini is great at. So TLDR my question is: Is it possible to recreate a shader that works like the ocean shaders in that I can take volume and particle attributes to drive things like sss, spec, refraction, etc. using the principled shader. If so, if anyone has any basic leads or can point me in the right direction to get started that'd be huge. I really want to get this shader to look incredible so I can share it with the rest of the community down the road if anyone needed to tackle something similar. Have at it team!
  18. Hi there, Very basic question, what is the correct way to get a custom shape volume, for example a spherical volume? When you plug geo into the volume node all it does is put a square bounding box around the geo. many thanks in advance
  19. Vex Volume Procedural Grid Rez

    Hi! I've found many examples with volumes using this render approach, but there is somthing I'm missing out. How does this VEX Procedural Volume gets its divSize/resolution? I've seen the "octree" option but it's another thing (An optimization for getting less render time) So how does this volume define it's grid resolution? I'm just curious!! Thanks.
  20. [SOLVED] 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
  21. 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. >>>
  22. 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.
  23. 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
  24. 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
  25. 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
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