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Found 73 results

  1. Hello ! In order to setup my different Disturbances and Turbulences inside of a smoke simulation, I'd like to know what range of velocity I'm dealing with. How would you guys do that ? If you have the proper method to do that just ignore what's under. The sim is already cached (density, vel, rest, rest2). What I'm doing for now : When looking at the node info there is vel.x, vel.y and vel.z. I don't understand why but I've read that these are scalar values and has to do with how Houdini works so why not. I don't know how to inspect this volume further than that since it's a volume the Geometry Spreadsheet doesn't display anything. And when I apply a VolumeSlice I get 10 different vel attributes per point. vel[4] matches vel[7], vel[5] matches vel[8] and vel[6] matches vel[9]. But not the rest of the values. This is very confusing to me.
  2. Hi there, For a school project I am working on a river. I am getting very nice results with the standard flowmap tools already, but I wanted to change some things. First of all, I wanted the river to flow quicker where it is narrow, because velocity = flowrate/area. This does work. Note that to make this work, I went into the flowmap to color node and got rid of the normalize, because I want values over 1 for the speed. Then I also wanted the water to flow quicker, so I thought I'll just take v.y and multiply it with 9.81. This seems to work at first hand, but then at the top of the slopes of my river, the water seems to flow in the opposite direction (back up). I am not entirely sure why this happens. When I set the gravity to a lower value, like 3, this doesn't really happen yet (or at least not visible). Can anyone explain to me why this is happening? Also, is there a better way of achieving this result, rather than just not normalizing any of the vectors?
  3. source flip fluid with velocity

    hey! I'm trying to emit a flip fluid with some velocity, I can add a generic velocity in world space but in my case I want to add velocity along the normal of the object sourcing...just can't figured it out yet
  4. Velocity Field for Pyro

    Hi Houdini Friends, I'm having an issue with my pyro simulation where I've tried to setup a velocity field that changes the direction of the flame at a right angle, after several attempts I can't seem to get the velocity field to affect the sim even though the movement for the sim is sourced partially from my velocity field. I've attached the scene file, if anyone could tell me what I'm doing wrong it would be much appreciated scene.hipnc
  5. Hi, i am trying to achieve the reference footage and what is in the image. https://cgsociety.org/news/article/2788/fx-tips-and-tricks-with-andi-kadiu while debris is moving ahead velocity needs to be negate in pyro... as u can see in my playblast its looks simple trail(snaky behaviour in flipbook)....and if you see refrences there is specific pattern in the smoke some kind of circular trail(red color marked in ref image) leaving behind...i am struggling with this for few days....if anybody can help or put some information here that would be great....i have attached test hip file and refrences. kindly have a look..thank you in advance flipbook.mp4 pyro_trail_v001.hip pyro_trail.mp4
  6. Pyro Disturbance for high vel

    Hello, How to increase the disturbance on high velocity source, Im using particles and volume as sources, both with very high velocity, but disturbance only affect after some frames, not on initial simulation frames, I`m using 3 "gas disturbance" microsolvers, 2 controling density fields and 1 controling the velocity.
  7. I am trying to blow up multiple groups of particles in a sequence.(boxes of confetti exploding at different times). The activation isn't really the problem as I can use a sop solver within a dop to activate the particles group at different time. The issue is to give them that "initial velocity" at activation time. The only method i found that is working to achieve the effect, was to actually import and merge many popobject and "activate" them one by one in a sequence , with the velocity attribute created at sop level This solution is of course very inconvenient. I attached a clean file, with just the different group all popping at the same time. a solution to have them delayed one after the other would be very welcome I just can't find an elegant method which works procedurally. Thank you for your help confetis.hip
  8. Hi all, I am trying to make a whirlpool effect and i am doing it by creating a circle and then copying it into itself creating a for each loop where every smaller circle rotates faster than the previous then copying it downwards and tapering it to make the typical "hole" that is formed. I previously made a mistake where i copied the volume created from the effect and put it as the source of the water and got it working but the surface water was stationary, now that i have the surface moving but when I let the effect run it only "spins" the top layer of the water and doesn't go any deeper into the water , any tips? or any help would be appreciated. Whirlpool13.hipnc
  9. Hey everyone! I've been digging through the forum but quite haven't found something that will help me get this effect i'm trying to achieve. i'm trying to work on an setup where I have particles stuck on a deforming grid and the particles become unstuck as they inherit velocity in Y(sop solver) and then with gravity they come back down. my current setup might be too complicated because it's proving very difficult to control. i am using a popnet where particles stick to the collider geo and become unstuck with a sopsolver "if (@Cd.r > .1){ @stuck = 0; }" does anyone have ideas on how to simplify the setup? is this something that the grain solver would be better at handling? thanks everyone! waveRipple_v003.hip
  10. Hi guys, I'm very new to Houdini. I'm coming from a Softimage ICE background so my brain is still struggling with adapting to a new workflow so bear with me if you can! I was following this awesome tutorial from the Entagma guys (linked bwlow). In short, I replaced the spheres he uses at the end with the trusty ol' pig head and now I would like to figure out how to make these pigs heads turn in the direction they are moving as they slide around the surface. I've spend a long time googling and looking at previous posts related to particle orientation but I can't seem to find a way to adapt anything to this scenario. I'll attach the scene file if anyone has any advice? I think I would need to do something like finding the point position from the current and previous frames and subtract them to create the direction vector but I can't find a way to do that in any of the PopVops. I tried using a PopLookat and setting the target to look at the velocity but not luck. Any help would be appreciated. I'm not great at VEX, I come from ICE so Pop Vops etc work best in my brain if thats possible. Cheers (not sure how to reduce size of video in this post, apologies if it shows up giant!) Entagma_GrowthEvenOnSurface_V01a.hipnc
  11. Hi, I have a question about copying velocity's to a flip simulation. I want to create a specific shape in the motion of the fluid. The only way I can get close to that at the moment is to source(copy) a generated velocity into the flip sim. That's because when I add the velocity, it overshoots too fast and I can't get that specific shape out of it. The only thing with copying the velocity, is that it copy's the velocities with a value of 0 as well, so the flip is completely at rest. I was thinking that this could be fixed with a mask field, but it doesn't seems to work as I expected. Is there anybody out there who can tell me what i'm doing wrong? Or other suggestions to get that result would be welcome as well! Actually, any help/advice would be appreciated! pumpVelToFlip.hip
  12. 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.
  13. 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,
  14. 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.
  15. 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.
  16. 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
  17. 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
  18. 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
  19. 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!
  20. 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
  21. 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
  22. 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!
  23. 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:
  24. 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
  25. 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
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