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Found 62 results

  1. Alembic Velocity Issue

    Hi guys I am having a rather strange issue. I have a particle system which is advected by volume from a pyro sim, and then I have bits of geometry copystamped to this system. But when I export this to Maya with ROP Alembic I am not getting velocity. What's strange is if I do a convert to points from volume using the original pyro sim, copystamp that and export it instead... the velocity works in Redshift Maya.. why does it break when using points from pops? Does anyone have an idea about what's going on? EDIT: Found a workaround. Convert the velocity to colour in houdini, and use it as the motion vector source in Maya mesh controls.
  2. Hi, I am currently creating a simulation with flip fluids that are affected by a vortex force. I need the velocity/lift attributes to be animated independently throughout the simulation, though no matter how I set the settings for either the sop geometry, or vortex force operator, the values will not change throughout the simulation. What is the proper method for animating these attributes for use in dops? Thank you,
  3. How is it possible to convert a single volume, to 3 volumes (velocity) I have shaped form that I am converting to a volume. I then need to convert that volume to vel.x vel.y and vel.z, to create a velocity field of. it is not optimal to just create a bound and then convert it via a "Volume" node, because I need to keep the original shape.
  4. Fast smoke simulation

    Hi there, I am learning about smoke in houdini and I am desperately trying to achieve an effect like this By this I mean a fast paced smoke puff that spreads out wide, like almost in a V shape. However, no matter what I do, my smoke always ends up looking very straigt. I can achieve the fast paced but then it looks even more straight I think. I tried making it faster by chaning the time scale, giving it a high buoyancy lift, using my normals as a velocity volume (in source volume node) and setting the scale of it to very high, setting the temperature scale to a higher values, etc. All these individual things work for the speed, but I keep ending up with quite a straight line, or something that isn't making sense at all. I tried adding turbulance, but this also doesn't help me to achieve that "v shape". I hope someone can explain to me what is going wrong, because I am totally lost.
  5. Hey magicians, I'm working on a flip river wich I need to have color attribute, followed H16 Flip Masterclass and get there, but then I tried to add color in several ways but I can't get it working. I tried adding a sop solver to dops with attribute transfer, but the color didnt worked on the motion. Also tried making source volume with points from volume with uv texture but velocity gets weird. Working river without CD Cd particles with weird velocity Any tips on how to fix this? attaching a hip. Thanks in advance flip_issue.hip
  6. disturbance when velocity

    Hi, Is it possible to have disturbance added only when a pyro sim is moving? I have a cloud being moved by a plane. Regular disturbance with default settings in pyro solver causes your sim to move. I don't want the disturbance to cause the sim to move, I want it to disturb when the sim is moving. I tried changing bindings, etc. but I couldn't get anything to work. Any suggestions? Thanks
  7. velocity field question

    hello guys, I tried to get velocity field in to POP and use advect by volume. but particles stop moving when they reaching some position. I can't find the reason of it and how to fix it. Does anyone can help that for me please? vortex_field_problem.hipnc
  8. Hi, The picture shows an object , create > test geo > add velocity > vdbFromPolygon with vel field > visualize velocity. I wonder how to split velocity to tangent velocity and normal velocity. I guess we don't have a node to do it by one click, and need to work on volume vop/wrangle. If anyone knows how to do it, I will appreciate it, thanks!
  9. Hello everyone! Even though I've had many help on odforce it's my first time posting. As the title says I'm trying to figure out how you would use particle velocity to increase and decrease the speed of a looping animation. I have done it with a copy stamp but I was wondering if there is any other way around it. Thank you in advance
  10. Hello, I have a feeling this is a common issue, but its a bit hard to explain / search for a solution. I've imported an animated alembic file, used unpack to get the points and put it through a trail node to get the point velocities, the problem is that the point count changes as some of the objects "disappear", so you get brief flicks of extreme velocity as the point IDs shuffle, I am curious about the method(s) for dealing with this problem.. Thank you
  11. Hello everyone, I have a problem on rendering bifrost surface in maya 2018,this is my render test: I have the velocity pass and displacement map output by Boss, but how can I render mesh by velocity? It means that the splash which with high velocity will be rendered with no displacement, and the other part of mesh which with low velocity will be rendered with displacement, I just want to render the surface with no thickness, how to cut the mesh in rendering? so I can render the mesh just like this: or is there any other way to render mesh? I want the splash is rendered with no displacement, and the other part of mesh rendered with displacement, and the mesh will be combined with outside infinite ocean, which can be rendered with the same boss displacement map. This is my RnD: Can anyone help me? Thanks!
  12. Hello everyone, I have a problem on rendering bifrost surface in maya 2018,this is my render test: I have the velocity pass and displacement map output by Boss, but how can I render mesh by velocity? It means that the splash which with high velocity will be rendered with no displacement, and the other part of mesh which with low velocity will be rendered with displacement, I just want to render the surface with no thickness, how to cut the mesh in rendering? so I can render the mesh just like this: or is there any other way to render mesh? I want the splash is rendered with no displacement, and the other part of mesh rendered with displacement, and the mesh will be combined with outside infinite ocean, which can be rendered with the same boss displacement map. This is my RnD:
  13. 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
  14. Hello Pals, Hope you all are having a great year so far. I am trying to do a shot with particles which needs slow motion on a certain camera moment. Basically, I just want to slow down the motion of my particles for few frames. I dont want to mess with the velocity etc as I really like the motion of my sim. I looked into time-shift, time-warp etc. But they always feel like a cheat and not much of a high quality solution. There is a "Scale Time" option on the POP net. But for some odd reason its locked and we cant key-frame it at all. That would have been the best solution, where we can just lower the timescale for bunch of frames and then resume it in normal speed. Can anyone just give me a brief why Sidefx would want to make this such a big deal and lock it on POP nets? Thank-you and have a great day! HD
  15. Hello ! Is there a simple way to transfer velocity attributes from a volume to another ? Or create velocity from scratch ? Thanks !
  16. Hello everyone... I have a problem with an RBD packed object inheriting velocity. In the file, I have the attribute active being set by another object, but the velocity doesn't kick in at all. The velocity works if I remove the point wrangle setting active to 0 and remove the sop solver. If I try a pop vop or a geo vop, there's some weird velocity behavior that happens. If I tick on override attribute, the velocity takes off big time and doesn't appear that gravity takes hold. All I'm looking for is initial velocity once the pieces become active. I saw a few threads on the side fx forums and this forum, but nothing I saw seems to be working. Any thoughts? test_active_velocity.hipnc
  17. Hey everyone, I really fell in love with some of the visuals created by Chaotic Atmospheres, link : http://chaoticatmospheres.com/flowing-city-map. They describe their process as a mix of displacement maps created in world machine all composited in PS, but I want to create and simulate this with velocity flows and possibly particles to create a more dynamic map for some of my architectural site plans. I've looked through and gathered different techniques for creating vector fields and I am a little stuck. I've used some of the techniques with manuplating vector fields with curves, creating a volume and driving trails, but the collision and erosion just hasn't produced the effect I want quite yet. With a few drawn curves on the grid, I can get a nice flow, but upon adding any more complex nurb systems, it just starts to group too many vectors. I might be going about all this wrong, but wanted to see if anyone could offer some more help or a more efficient technique. The end goal would be for the vectors to be able to be animated to visualize flow from the city boundaries outwards towards the edges. Thanks to anyone who can offer any advice/tips/help on this endeavor.
  18. hi guys as the title says really i've got an anim i imported - i dropped down a trail sop compute velocity and now i want to turn that into normals. I tried attribute promote and a wrangle with @N = @V; but it didn't seem to work can anyone advise me how to go about doing this? end result is having some control of a pyro sim around a character eg smoke swirling up and around his limbs so i'm using a tip by Ben Watts to try and blend those animation normals/velocity with normals that simply face upwards. Theres probably other ways to do this but i've no idea and tbh this whole thing is just an guessxperiment heh heres the tut i was looking at....
  19. 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
  20. Is there a way to calculate the angular velocity from spinning points that only hold "N" "v" and "up", without using the trail SOP?
  21. Applying vel to cloth through sops

    Hey, still playing with the FEM cloth model in Houdini. Found that applying forces through the drag model works much better in terms of simulation quality. So I generated some vel field in sops and imported it into dops. Unfortunately the velocities aren't affecting anything. I took the sails asset from orbold as an example but still something isn't willing to wor. Hope someone has got an idea. Attachments: vel.hiplc
  22. Hi. I am a beginner in Houdini studying in Korea. I have not been able to find a way to do this all day. I created a snow that flies quickly with particles. After rendering the mantra to the snow I want to give a vector blur in Nuke, but it is difficult to draw a pass. I can not continue vector blur in velocity direction. How do I make it look like a picture? I have not found it in a few days. Please help me.
  23. hi everyone, i have a destruction cache from maya, i use trail to compute velocity and transfer to speed; i group some points base on speed (e.g speed >= 8), and scatter to generate smoke; but speed keep changing, if the point speed less than 8, i will lost it and result in my smoke trail is broken... so how can i constantly keep these points if their speed is greater than 8 once?
  24. 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.
  25. Get Sop Vel to pops

    I'm trying to find a way to get bring in the velocity from a field i created in sops into pops directly. I can do this easily in dops with a sop geo and a particlestofield node, but i can't seem to replicate this in pops. I've seen this done before in a pop wrangle, but I don't know the code myself. Can anybody help me out?
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