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Found 29 results

  1. Smoke density based on ramp

    Hi everybody, I am new to houdini and i am already scared. I know how to emit pyro from colors by using ramp than a delete node with a $CR < 0.1/.5/.8. on my emitter it work but i want to control the "density" of the emission based on the gray level of my ramp/paint node. Meaning white zone = 100% emission dark zone = 0% thanks you
  2. 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
  3. Hey folks, proud to present LYNX Tools, a collection of production proven open source tools to accelerate your workflows! All mentioned tools are free to download via the links below and are licensed with a full HoudiniFX license. All Houdini Assets have complete Houdini native documentation available. Repository: https://github.com/LucaScheller/VFX-LYNX Lastest stable release: https://github.com/LucaScheller/VFX-LYNX/releases Please give them a test drive, so we can improve them further Roadmap | https://trello.com/b/f8Pgip7s/lynxpipeline So far there are three tools: LYNX_force_general | Tweak your sims with this all purpose & intuitive force field. Built to mimic force fields in other DCC applications, but with support for more features and a natural Houdini user experience. https://www.lucascheller.de/vfx/2019/03/24/vfx-lynx-houdini-force-general-asset/ LYNX_fabric | Create fabric/weave patterns with ease. Perfect for creating that holiday sweater you never wanted. https://www.lucascheller.de/vfx/2019/03/16/vfx-lynx-houdini-fabric-asset/ LYNX_velocity | Get control of your velocities via an intuitive UI or groom them for absolute fine tuned control. https://www.lucascheller.de/vfx/2018/11/01/vfx-lynx-houdini-velocity-asset/ More info on my website, including full release logs: https://www.lucascheller.de/blog/ Houdini User Group Munich Presentation: https://vimeo.com/334887452
  4. Hey, total noon here Just started learning houdini recently. Made a candle flame and adjusted it like I wanted it. When I am converting it to VDBs I can't get the density right and thus it looks wrong or is invisible in maya. The file is attached, any help is appreciated CandleJet.hip
  5. Hey guys, I'm making a smoke a sim of a person blowing out smoke (vape smoke) and when the smoke starts to dissipate and get's close to fully disappearing the resize fluid dynamic container just shrinks and clips that area entirely. Looks very jarring and obvious fake. I don't know why this is happening. It still happens when I increase my substeps to 3 so I don't think that's the issue. When it's at substeps 1 - the clipping still occurs but more smoothly (if that matters). I've attached my scene file and a flipbook of the crime. I'd really appreciate any help with this! Smoke_03_ForReddit.hip Pyro Clipping_For Reddit 2.mp4
  6. Pyro showing fuel in render?

    Hey, So i im having this small issue where I think the fuel? is showing in the render and it is ruining my pyro sim to look like a clean flame. I have density turned off, so there is no smoke and temp and heat are the only attributes being used in the material node. I'm assuming fuel is the source of the issue and it is being rendered through heat. Any ideas on how I can remove that small cloudy emission on top of the flame (in the picture below), in the video you can see it in the middle of the flame, you can see it on the 2nd and 3rd one but it doesn't seem to appear on the the black body one (1st one) It seems to only happen when I use the ramp to colour the flame
  7. Recreating an ultracentrifuge

    I'm trying to recreate an ultracentrifuge that seperates high density particles from low density particles. My current setup is two fluids with separate densities being emitted side by side to fill the container. Then once the container is fully filled I start up the "centrifuge", a pop axis force to spin everything at high speeds. The problem is it just acts as a blender and not a separator. I have a little divergence to pump up the fluid in the beginning but then it's removed. The densities are about 400 kg/m3 apart. I've tested fast and slower with different drags and settings but still just blends. Anyone else try something like this? Maybe I'm missing something important (more than likely, ha). Thanks! Update: kind of working now adding some mass, drag, and applying the rotation only to the low density particles. Faking it till it makes it I guess.
  8. Fluid Drop Simulation issue

    Hey guys! I'm working on a project using fluid to simulate a drop (something like oil drop) falling and colliding with an object. The thing is that the client ask me if I can separate the drop when colliding with the object in another smaller drop and I don't know how can achieve that, I'm looking for something like have different density in the same fluid object or select some particles inside that can be affected for another force but the fluid is fluid, not particles so I'm lost in that! BTW this is the sim (the second part is the fluid). Cheers! gota v1.mov
  9. Hi!! I have subdivided the primitives of an icosaedron. What I want is for each primitive, to select a random number of subdivisions (the small black triangles) , extrude them and control their density with an attribute. How can I do that?? POPULATION -HAPPINESS.hipnc
  10. Issue advecting vectorfield

    Hey guys! Trying to figure out the whole custom vectorfield aspect of the pyro solver, but running into some issues.. I created a new vectorfield (Cd) under the smoke object, importing a Cd vectorfield that i want to use in a source volume node (replaced velocity with Cd to Cd as another forum post on here suggested). Then I added a gas advect field microsolver to the advection input of the pyro solver. With the multi checked on the visualization and Cd in for diffuse, I can see that the vectorfield is properly being sourced, but it doesnt advect by the velocity field for some reason, it just sits there. The gasadvectfield node should move the Cd by Vel right? I've found some good forum posts about this here, but for the life of me can't replicate the effect. Any suggestions / advice? Thanks! Cd_advect_v01.hiplc
  11. Hi, I want to render a custom pass for clouds in mantra. The reference jpg shows a custom pass from Maya (density / ambient) and the alpha for the same clouds. In Maya a gradient ramp was used on the incandescence channel. Basically where the clouds are denser should be black and the opposite, for lower density I should have white. Can I replicate that with mantra? I'm using the sky rig tool so everything is calculated at render time. Thank you!
  12. 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
  13. 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
  14. Advice needed for pyro sim

    Hi Guys, I am currently working on a shot where I need to simulate an object falling slowly through deep water whilst bleeding (The more blood the better). Initially I began with a pretty simple setup, An emissive object, a collision object and a divergence volume which is being used for expansion. The problem I am running into is that I need the smoke to continually expand, whilst becoming more diffused and transparent, but to always remain in the sim. So I have disabled dissipation as I don't want to lose density, but this leaves me with a dense volume which isn't transparent or diffused. I would like the density that is in the sim to have an aged based blurring. I did try to achieve this with a gas dissipate and heat field but this still wasn't right. I have also spent time trying to tweak the pyro shader to achieve the desired effect but I am not having much luck. Below is an example of the look I am trying to achieve. Between 0:21 and 0:34 Any advice will be greatly appreciated. Many thanks, Clive Blood_in_water_odforce.hip
  15. Hi folks, which node can set texel density to UVs? And why are all the polygons are separated in the UVs? I tried to use Fuse UV but that's not solved it. Maybe I missed something I'm newbie to Houdini :]
  16. paint density

    hi guys i use paint node to get particular scatter points for my object but when i fracture it, pieces look so long i guess it is a density problem. i just want irregular pieces but more points in some areas.how can i fix it.please help me... test.hipnc
  17. Change Density of Flames Pyro

    Hi, How can I adjust the density of the flames in a pyro render? Right now, I have smokeless flames, and the flames are not dense enough. You know how you can change the density of the smoke? Cant you do the same thing for the flames? In visualization of the smoke object, I can make the flames appear more dense in the viewport by going to pyro's visualization go to emission then scale it up. You can see the results below. How can I do that in the shader, though? The flames are just to thin and transparent. The only thing I see is the fire intensity scale, but it makes it brighter not more dense. Any suggestions? Thanks
  18. Hello,I have 2 questions about the hair:1. When I paint the density attribute the hair guides are reacting based on the vertices, i.e. when I hit only a vertex guides disappear (or appear). It means that with low polygon count I can't avoid stepped guides boundary. But with more subdivisions it is practically impossible to work due to long cooktime after each brush stroke… How can I deal with the guides between the vertices without increasing subdivision? Attachment below describes it.2. To delete hair guides (for example, for hairline or beardline on the head) I use Length Adjust shelf tool with Target Length value of 0.001 (complete 0 is impossible), but this still leaves hairs roots as dots when rendered. Is there a cleaner way to delete the hair neatly along the boundary?
  19. 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
  20. Pyro Attributes

    Hello! I'm encountering a little problem with Pyro Fx. When I export a geo file from any fire, the attributes of heat, temperature and fuel look good in the viewport but when I render them, I get a particles cube. It seems that those attributes are not exported in my bgeo files (I tried with Vdb files and got the same result). Is it a bug or is there a step that I missed in the export? Thank you!
  21. Smoke Density Driven By Velocity

    Hello! I was working on a basic smoke sim where the smoke was being emitted from animated type-geo. I computed the velocity of the geo with a trail, then plugged that into the fluid source to create the density for the smoke sim. That is all working fine as you can see in the render. However, I'm not happy with how the smoke just appears all at once. In other sims I've used an attribute wrangle to map the density to a ramp and have the density fade in but in this case I want the smoke density only to be generated when the velocity starts to increase. I played around with trying to get the velocity data out of VOPs but I really was just taking stabs in the dark. Any suggestions would be appreciated. smoke_test_v02.mp4 text.abc smoke_density_v01b (1).hipnc
  22. One simulation 2 densities

    Hello, I'm doing an exercise of the launch of two smoke grenades . My problem arises when once made the simulation I want to save each smoke in a different file to give different shaders . I cant do it because both smokes are in the same "smokeobject1". Each smoke interact with each other. Thanks!
  23. Hi guys, i am struggling with stupid problem, i want to convert my bgeo files to VDB to later render them with arnold. But on convertvdb node i have that density channel is <empty>. I don't know what is wrong with my scene, for test i created same setup flames from the shelf, didn't change anything and it's working. Do you guys have any suggestion? Thanks firenosmoke_v003.hip
  24. Exploding RBD's in FLIP fluid

    Hi Guys, I need some expert advice and insights on this project I'm working on. I'm doing some RnD first before moving to bigger scale so I can provide you guys with the HIP file. The objects however (barrels and table pieces) I cannot share with you. But maybe there's something in the dop nodes or solvers that you can spot right away. I'm working on a flood scene where there's a lot of debris and rubble that needs to be transported by the water. Please have a look at the video. The barrels seems to acquire a spin which at one point is out of control! I can imagine this could be the rotational stiffness... but the exploding (and stuck) piece of table is still a mystery at the moment. As you can see I'm also having trouble controlling the buoyancy of the objects in the fluid. Right now I use the density to try and float pieces but it's not entirely working the way I want it. To sum it up: - The wooden planks need to float - barrels need less spin and need to be embedded more in the fluid. - the tables obviously need to stop launching like superman . any advice or tips are greatly appreciated . High-RBD_count-in-fluid-006.hip
  25. I've been getting back into FLIP, and trying to replicate this test done in Naiad a while ago: https://vimeo.com/25020677 Using some POP nodes, I know I'm getting attributes changed on the points properly, but I can't figure out why the solver isn't pulling the higher density particles down under the lower density ones. I even played with @mass, hoping that'd do it, but it doesn't. The POP nodes are affecting the points just fine; when I crank up viscosity/velocity/color, those are set properly. The red points should be rising up, and the teal/blue ones should be sinking since they're heavier: Does anyone have some insight(s) as to why the density isn't making points rise/fall? Thanks! dense_flip_separation.hipnc
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