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Found 55 results

  1. 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!
  2. 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
  3. 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
  4. 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!
  5. 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:
  6. 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
  7. 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
  8. Hello ! Is there a simple way to transfer velocity attributes from a volume to another ? Or create velocity from scratch ? Thanks !
  9. 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
  10. 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.
  11. 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....
  12. 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
  13. Is there a way to calculate the angular velocity from spinning points that only hold "N" "v" and "up", without using the trail SOP?
  14. 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
  15. 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.
  16. 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?
  17. 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.
  18. 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?
  19. FEM Alembic - Angular Velocity not Centered

    Sup guys, I've just imported an alembic from a client - it's just a static object - and it's already placed a few units up from the ground. I need to give it some initial angular velocity to make it spin while it falls but, it looks like, the angular veocity is coming from the origin gnomon. Thx /Alvaro
  20. FEM Alembic - Angular Velocity not Centered

    Sup guys, I've just imported an alembic from client - it's just a static object - and it's already placed a few units up from the ground. I need to give it some initial angular velocity to make it spin while it falls but, it looks like, the angular veocity is coming from the origin gnomon. Thx /Alvaro
  21. Packed Objects InitialVelocity ???

    Hey guys, in rbd packed objects if we turn on inherit velocity from point then it does this only on the creation frame, what if i want to assign some velocity only when active=1, how can i override the inheritvelocity parm. Any help would be appreciated.
  22. 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
  23. Hey, I'm curious about different approach for artistically control the creation of a velocity field. I've learn how to make nice noisy, curly etc.. fields, but when it comes to controlling them more, how would one proceed ? could some curves be used as general guides for the velocities? And the perturbed slightly by some noise ? I bet there's many ways to do it, I've seen some nice VolumeVOP work in some tut (volume trails), but I wondering about the best way to get real control. thanks in advance for any input
  24. Pops following animated mesh

    Hello everyone ! Does someone know how to use an animated mesh for driving some velocities of particles ? I have done a sim that I like but I want it to follow the character's animation... The particles born in the chest and goes to his head which is rotating... I'm pretty new to pops, I think that maybe I can make it move through a pcopen but maybe it is a bit too much for what I want to do ? Also, I'm not pretty sure about how to make it... Maybe it's possible to feed the pcopen with a scatter of point on the surface of the character ? Thanks a lot and have a great day ! (Once finished and online I will try to post it as a comment !)
  25. Hello all, Any idea how to add velocity to a growth propagation ( from bwdesign tutorial ) ? Here is a sample file, I don't know what to do. I would like the points to have velocity ( in the direction of the growth... ) thanks. Here is a sample file without velocity of course growth_noVel.hip
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