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Found 286 results

  1. Hi All! I'm wondering if anyone has run into this and found a good solution, it's been popping up in my low-to-mid viscosity sims for a while. Perhaps I'm missing something stupidly obvious? Collision geo/field are fine and the interface between fluid and collision object looks great before turning on viscosity, then I get these grid artifacts that are tough to get rid of. Reducing Surface Extrapolation way down in Volume Collisions helps but doesn't completely remove the artifacts. Also, using a high slip-on-collision value helps, but I usually don't want the sliding behavior with sticky viscous fluids. Reducing Grid Scale reduces the relative grid size and helps too, but the artifacts are still there, just smaller. Attached file is somewhat of a worst-cast example, just curious if other folks have dealt with this before. I know I can run some post-sim tweaks to clean up the collision surface intersection, but I've also noticed that the artifacts reveal themselves on the outer surface of the fluid if it gets thin enough, which is not so easy to fix... 01 - viscosity disabled 02 - viscosity enabled 03 - viscosity enabled, surface extrapolation 0.01 Thanks in advance for any help/ideas!! --Dave DStewart_FLIP_ViscousCollisionStepping.hip
  2. Hey everyone,My overall goal is to simulate liquid poured into a glass with ice cubes inside, with the ice cubes floating.Everything works normally until I enable feedback forces: Normal: https://gfycat.com/LameCarelessIzuthrush With feedback: https://gfycat.com/FlashySolidFreshwatereel There's a ton of particle loss. For these sims, particle separation is 0.004, grid scale is 2, feedback force is 1, and max FLIP substeps is 10.The best I got was to maintain volume with 1.75 grid scale, but with overreacting ice cubes: https://gfycat.com/MiserlyEmbarrassedAfricanbushviperI've attached the Houdini file for this below.Anything related to this problem would be helpful. Why is there particle loss, even without reseeding or with many substeps (I've tried using 20)? Is there a problem with how I'm using feedback? Why does changing grid size cause volume to increase or decrease?Thanks! ice-tea-milk_027_017.hipnc
  3. Hi there! this is my new Canary Surge V2, improved workflow for whitewater, foam and shading stuffs.Please watch in HD 720. Vimeo compression kill of the fine details sorry. http://ipsvfx.com/project/canary-surge-v2/
  4. Hi, Is there a way to automate flip cache process in houdini? For example after particle cache complete it will automatically start compressed cache and then surface cache. Artist no need to press save to disk each time.
  5. I havent realy used Flips in houdini, so i have this realy basic problem.... So I have set up this scene from shelf tools, and it seems i cant figure out how to make a basic glass fill with fluid, it just dosnt fill up, it seems like particles are been deleted.... I have attached my test/example scene. I hope someone can explain me why its not working. Thanks in advance, Tom glass_fill_basic.hipnc
  6. Hey guys! I'am pretty new to Houdini and I need some help now. I've set up an rbd destruction and I want fluid to interact with it. Here is the reference I want to achive: The fluid I set up was either incredibly slow to sim or just did not stay inside the collision object. I didn't find any good tutorial for this kind of flip-rbd interaction. Could you recommend any method you would handle this problem? I atteched my hip file so you can see what a mess I made Thanks a lot, Máté bottle001.hipnc
  7. I am trying to generate whitewater in a Flattank using whitewater shelf tool but the result is not proper. the particles are freezing and not following the motion of flip particles and also sometimes they are flickering. I have included a video link to demonstrate the problem. Please help me to solve the issue. best regards, https://drive.google.com/file/d/0B1abbA5_-CZvWHhMbndMTGt2VGM/view?usp=sharing
  8. Hi there, I'm trying to control flip particle count per voxel. The idea is to evaluate particle count per voxel on every step (Gas Particle Count) and then analyze the pcount field.. If pcount > n - delete some of particles (pcount - n) to make n numbers. And if pcount < n - add (n-pcount) particles. Any help is highly appreciated. Thanks,
  9. Hi guys, trying to find a solution to render houdini flip sim in Maya Renderman, i exported a rib sequence from H, but not sure that i exported all the attributes (something to promote?) the rendering department here, doesn’t see the v att and Cd att in my rib sequence. my maya knowledge is close to nothing and i can' t check what s wrong with my export my first question is : could you explain me, guys, how to export from Houdini, a ready to render Rib sequence for mayaRenderman v21? second question is : is there tricks to read H attributes in maya?, connect it to shaders?, and also get correct velocity motion blur(since it's changing topology classic moblur doesn't work) thx by advance for your attention
  10. Hi all, I am using the new waterline feature in flips in H16. It is working fine at first, but I tried to key the waterline to move up during the simulation and it seems to have no effect. The particles still escape even though they are below the waterline. The simulation only respects the initial waterline level and does not move dynamically as its keyed. Is this normal behavior? Any idea what might be causing this and how to properly move the waterline as the simulation advances? Many Thanks.
  11. Hello, I created this water simulation of water hitting some rocks on the shore. I'd appreciate any suggestions on improvements. My main issue I feel is the white water, it looks like sand and any advice on how to go about making that area in particular better would be greatly appreciated. Shore V1.0
  12. Hey everyone. Hope you guys are well. I need some help with a shot I am working on. Basic idea is i need to have bits of strawberry to fall into swirling yoghurt,hit the surface,swirl around and slowly get pulled under the surface. I've got the swirling yoghurt working but when I drop my RBDs into the container they plow right through the flip sim. I've tried tinkering with the Feedback scale,Density and so on but nothing works for me. If anyone of you Wizards can have a look and shed some light on what I am doing wrong it would be greatly appreciated I have a scene attached Swirl_03.hip and my swirl force source geo FOR_OD.rar Thanks again Cheers Dimitri Swirl_03.hip
  13. I'm trying to isolate those areas of a FLIP sim, that have been in contact or collided with some geometry. My problem is I've got something that works for the particles as long as they are close to the surface, but as I intend to create some dripping and surface tension effects. At the moment, I am assigning an attribute to the points which are colliding, which allows me to isolate the fluid on the surface, but of course that gets overwritten each frame. There must be a more elegant solution for this, but I cannot figure it out at the moment, so any ideas or feedback pointing me towards a better solution is welcome. collideStick_v001.hipnc
  14. Hello. Is it possible to setup a distributed sim of a river that is coming down some kind of slope? Every example I can find takes some kind of already filled tank and goes from there. In the help there's even a note saying "this option is not needed for flowing rivers" (which might be refering specifically to the distributing pressure setup, but I'm not sure), but why is that? From my limited testing with the tank-like setup distributing the sim seems to speed it up considerably Thanks
  15. hey houdini users, i'm doing a flip simulation for strawberry falling into chocolate but i cant figure out the right surface tension for viscous fluid and i don't know how houdini calculate Surface Tension or how to find the relation between liquid mass-density and surface tension ? and also does houdini calculate it in millinewton per meter ?
  16. hey houdini users, i'm doing a flip simulation for strawberry falling into chocolate but i cant figure out the right surface tension for viscous fluid and i don't know how houdini calculate Surface Tension or how to find the relation between liquid mass-density and surface tension ? and also does houdini calculate it in millinewton per meter ?
  17. Hi, (Sorry if this kind of question was asked before) I'd like to set up a flip fluid in a fashion similar to naiad's, where the particle density can be set up separately for the surface and the volume of the fluid. (See attached image as an example) Now, the generation of this is pretty obvious, but I'd like the flip solver to behave as if the in-volume particles had a bigger scale or radius (so I'd need less particles to fill the same space). I tried to adjust the pscale attribute of the inner particles, but that doesn't seem to affect the solver. Any ideas would be appreciated... imre
  18. Hello everyone! I am creating a pool of lava and am struggling with creating displacement for it. The problem is the remeshing every frame. How can you make points which are generated at the first frame follow the colour they have been given? My idea is once I have figured this out, to use those points for the position of the displacement. Any help is greatly appreciated, thanks! points_follow_colour.hip
  19. Hello! I feel like this has an easy solution that I'm just totally missing, so at the risk of sounding dim: I have some scattered points over some geometry, and I want to use those scattered points to emit/create whitewater. What is the process involved in having points used in the whitewater solver? Thank you!
  20. Hey guys! I'm new to Houdini and I've ran into a problem which i can't seem to fix. I was hoping someone on the odforce forums would know the problem. I have been trying to make a tool to generate snow. Thanks to a tutorial on snow simulations from cmiVFX and the great documentation from SideFX things went pretty fast, but the last couple of days my simulation seems to collapse/melt whenever it seems to reach some sort of resting point. My intention is to have stable snow which I can make a character walk through. So I want the particles to stop melting away when my simulation stops moving. I added my scene so you guys can take a look. Any ideas on how I could fix this? Many thanks in advance! snow_v18.hipnc
  21. Hello guys, i have a serious mesh flickering problem in my flip simulation. The timescale in the flip solver has been animated to slow down the simulation. Looking at the particles everything seems fine, but when it comes to meshing and the particles are moving really slow, the mesh starts to flicker and holes are forming and disappearing every frame. I've tried increasing the resolution, lowering the particle separation in the particle fluid surface node (or vdb from particle fluid, i've tried that as well), lowering the grid scale or the particle radius scale, the flickering changes but it never goes away. any help is greatly appreciated thanks in advance slowmoving_flip_flicker.hip
  22. Hey guys, I'm working on this snot simulation and I need the top part of it to be "attached" to a nose. Any ideas on how to proceed? EDIT: Right now it's like this but I need to "constraint" it to a character. Thank's Alvaro Snot - v1-a.hipnc
  23. Hi, I am playing witht that very cool example file from the doc: ( local doc only at the bottom of this page: http://127.0.0.1:48626/nodes/dop/popcurveforce ) It shows how to use a Curve Pop force to direct a flip fluid. What I would like to do now is to use a turbulence force (there is already one in that example on the popforce1 node) to influence only the low speed particles. How can I make a force to influence only the particules moving below a certain speed? And maybe with a little gradient from zero at that speed and becoming greater when the speed becomes lower? I think that would prevent the fastest one to get too much speed and leave the curve path. I got the idea from this example where "Myke" is saying in the comments that he used a turbulence force to influence only the slow particles.:
  24. how would we setup fem flip interaction flip pushing around fem body? Fluid force? Does feedback needs to be enabled on flip solver? Looks very buggy this in h15.5 .565? If I increase fluid force it is pushing flip upwards? Anyone have experience with this I want to get something like this going on http://physbam.stanford.edu/~fedkiw/animations/starfish_150.mp4 starfish_v001.hipnc
  25. Houdini 15.0 - simulated using flat tank, and custom forces added in front and back of ship to get the wakes.render time : 15-20minsrendered in mantra and comped in nukeThanks to my mentors who taught me the awesome tricks to achieve the results.model downloaded from - cadnav.comAny advice or feedback appreciated.