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Found 75 results

  1. Hi all, I'm working with some mocap meshes that I'm trailing particles over using the 'minpos' technique in POP VOPs. I'm getting a little stuck though, as when i make trails of the particles, these obviously trail behind the mocap as the keep their birth XYZ coords. What I'd like to achieve is that the trails adhere to the surface of the body/geo in the same way that the particles do, so i end up with something like 0:24 > 0:26 of the attached video. Maybe I need to do something within a sop solver? perhaps dop pop is the completely incorrect way to go? Any hints or tips greatly appreciated - I've attached my .hip here should anyone have the time to take a look! Thanks! (hints on filling the volume as-in the video will also be met with rapturous thanks... I'm not even sure where to start with that one.) surface_particles_trail_test.hip
  2. 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
  3. Hey Guys. Quick question. I have a volume that I am applying a cloud noise to, and I want the amplitude of that noise to be driven by an age attribute. my steps so far. - create points with age attribute - copy spheres onto the points - convert to a VDB fog - apply cloudnoise How do I get my age attribute from my points into effect on a volume driving the amp of my noise? Cheers
  4. Would it be possible to have a sphere primitive or any geometry affect the density of a volume (fade density from 0 to 1) based on distance between the geometry's pivot (or all points) and the volume?
  5. Hi there, I've got some strange problems with the collision volumes in flip. The static object itself shows a clean, closed volume; the flip object on the other hand shows me a mess. Nothing is closed, the collision volume seems to be made of stripes. How does this discrepancy between static object and flip object happen regarding collisions? Actually the flip particles are floating inside the object. Got a new ship model and obviously some diffuculties making it work I also tried to use for each loops to convert each single object the shi is made of into volumes in order to merge them together insteat of turning the whole thing into a volume at once.
  6. Hi, interesting: if I activate the fluid-sop, the templated out-sop (the chunks) disappear. Is this normal? RGB_WALL.hip
  7. Hi there, First time post here. I'm relative new to Houdini and I really love already it but there are some things that (probably) are really simple but I just can't figure out. I must admit that I have very little experience in expressions and python (which I'm already working on) but for something I'm currently working on I'd hope to have some help before I get proficient enough in that. I have a volume source which emits in the Y axis and I wanna use the gas disturb fields but only on the voxels that are being emitted for the first second, after that I want other microsolvers that I have in the scene to take over. What kind of expression should I use for that? Should I first add some kind of life-attribute and then refer to that or is it much simpler? I looked at the local variables in the gas disturb microsolver but as far as I can tell they all refer to the simulation step time which is in the beginning of the whole simulation. Some help ore pointers are really appreciated. Thanks!
  8. Hi, I have a large volume where most of the volume has no density but some velocity. I want to export vdb's and to save disk space I want eliminate the velocity where I have no density. I found a way by using a volumeVelocity sop where I use my density as a mask, but I'm quite sure that there is an simpler way. I tried to do it in a convertVdb where I use the density vdb as a mask for the velocity vdb, but this had not influence on the velocity vdb. So the question is: What is the most efficient way to mask a velocity volume with a density volume (or vdb)? Can't post a hipfile at the moment, sorry.
  9. Hey all I've been watching a few cg films of late.. stuff like wallE and wreck it ralph and Shrek. All these films use large chubby characters.. which seem to interact with their own volume mass and also the env around them. So my question is how is this being done? It's something I wanted to do for a good while and don't know how to go about it.. eg getting those nice effects when a character pushes their arm close to their body and the mass squashes but maintains volume.. or ralph when he bends an arm but the volume is maintained. Can anyone recommend techniques for this? Houdini or maya perhaps? I'm just lost where to start.. is it something that's simulated after the anim? Or is it something part of the rig that the animator can visualize? Any thoughts welcome. I'd really like to try and figure this one out and there's a good few vfx guys on here so hopefully I can get some insight Ta Ant
  10. Hello, I'm Trying to create a smoke cloud loop. After generating a sim and creating a bgeo sequence. I use 2 time shifts to offset my animation and use a Volume mix to merge one onto the other smoothly. But for whatever reason the first (and thus last) frame of the result it looks as if one bounding box is cropping the volume.. but if I do a lower resolution of the exact same sim, it's all fine! I can't figure out why, how to force a certain BB to be used. help or previous related post would be greatly appreciated. PS: also attached the hip file. SmokePuff_07_V1.hip
  11. Hi Guys, I just started learning about smoke simulation. I am trying to create a tornado simulation using smoke solver instead of Pyro. I followed the custom force tutorial from Ben Watts. The problem that I am facing is that when I start my simulation, after a while the smoke spread out and remains floating and it doesn't follow my velocity field. How can I get it to follow my velocity all the time, or is there anyway to kill the smoke based on their age? I have attached a quick preview and my hip file. Thanks, Preview.mp4 Tornado_test7.hiplc
  12. Hi everybody, I'm working on a smoke simulation, but in the display when i look at to the density of my volume i'm bit confused about the result. Instead to have a shadow on my volume i get something as a black hole (like if there was no density, see the picture below, it looks like my volume is sliced.). Although I can see the density appear if i put another light to lighten the shady part of my volume i would like further explanation to make my mind clear. So i was wondering: -Is it normal to see a black hole instead a shadow ? -Do i lost my data, or the volume is not display but the data is still there ? -Is there a way to get more accurate display on the volume, to see a real shadow instead nothing (a setting in the light or anything else ?) ? Thanks a lot for you help, Marles
  13. Hi there, very new to houdini.. I've got an 'IsoOffset' node, with the output type to 'SDF VOLUME' and the mode as 'Ray Intersect', when test geometry is plugged into it the functions succeeding the 'IsoOffset' (trails, connected points etc) work fine! - but when I plug MoCap data into it they don't work and the node gives no error either. Is there a button which to needs to tell the ISOOFFSET node that this is moving geometry? About the MoCap data - I've tried this setup using both 'Object Merge' into the ISOOFFSET node, and the standard nodes that come with it when you import Filmbox FBX into the ISOFFSET node. many thanks
  14. Hi This may be really stupid but I was working on a volume wrangle, and I noticed that the printf() function does not work on this kind of wrangle node... Is it just me or am I making some kind of stupid mistake? In the pic the node to the left prints nothing, instead of the node of the right (wich has the same code), wich actually prints "Hello" to the Houdini console.
  15. Here is a simplification of my problem: I have two side-by-side volumes, and one of them has voxels that are twice the size of the other's. Or, another way of wording it – I have two volumes that are the same size, with resolutions e.g. 10x10x10 and 20x20x20. When I render the image, there is a seam between the two volumes. This seam is not there if the two volumes were have the same voxel size. How do I remove this seam? Is there something I can do in the shader? seam.hipnc
  16. Volume convolution on the GPU using OpenCL. For 27M voxels using 100 iterations, OpenCL is 650 times faster than C++ and 12525 times faster than VEX.
  17. Hello, I have posted blog post explaining some concepts of volume displacement and how to do it with Arnold (in Houdini but possibly in other packages supporting Arnold as well). link Hope somebody will find it useful. Juraj
  18. Guys, i've just noticed my emitter is hollow. Can anyone show me why is that happening and how to emmit from the whole volume? here's the file in case you want to have a look: https://www.dropbox.com/s/y0363g0rz3w4plt/Star_Shapped_Emmiter v1-c.rar?dl=0 here's how i've created the star shapped + flip shelf added nodes: and here's a video just to prove that i'm not crazy Cheers, Alvaro
  19. Hey Guys , i have a scattered points on a surface , and this points have noise as their color , i want to make a volume from those points , and also multiply volume density with points color , but cant find any way to transfer attribute from points to volumes . is there any solution to make this happen ? thanks
  20. i want fade my volume when its near to other objects , anyone know how can i do this with volume vop or other solutions ? thanks
  21. Hello. I was wondering – can anyone think of a way to compute a SSS point cloud that treats closed, overlapping geometry as a single volume. I have meshes that would be very tedious to unify, and I doubt poly -> VDB -> union -> poly -> reduce can give me a crisp enough result. Alas I don't have enough insight into the workings of how SSS point clouds are mapped onto polygonal geometry, but wondered if a volumetric approximation of the meshes with sufficient resolution could serve as the basis (somehow). Any ideas / suggestions welcome.
  22. I would really appreciate help with doing the simplest possible volume render using RenderMan in Houdini. I always just get a black image. I think my issue is that I don't know how to set up a volume shader... A sample .hip file, or just telling me which nodes to use, would be very appreciated.
  23. Hi I am trying to rotate a volume so it aligns with the original geometry. (align along x axis - convert to volume - revert back to original place) I tried setting the primintrinsic, but the pivot point is shifted relative to the original geometry, there is a way to specify the desired pivot for the matrix? Any ideas? Thanks) volume_rotate_v01.hip
  24. Hey guys, I have an alembic file of an animated deforming creature from maya. I am converting it into a VDB volume and applying noise via vop sop. I created a rest.x rest.y rest.z volume to compute the volume rest fields for animation. Now the problem is, after I create these volume rest fields I need to then deform the volume rest fields to match the alembic animation so my rest field will deform along with the geometry and the noise will stick to it without any slipping At the most basic level I can manually keyframe a xform sop, but the noise slips when there is deformation; i.e. this only works with translation or rotation So is there any way to somehow transfer the deformation of the alembic animation over to the volume? I tried transferring density to points, deforming via lattice and then transferring back, but this caused a huge loss of detail/unpredictable results. I also tried transferring volume attributes, along with a thousand other things, with no luck. I posted an example file. Thanks! volume_deform.rar
  25. Hello everyone. I am doing a FLIP sim where I have a jug with liquid, add some custom velocity to make a vortex like movement of the fluid and then cut them so the fluid can go to rest. As you can see on the screenshot, the fluid is loosing volume. Is there a way to retain the original fluid level withouth adding some extra emitters? I am guessing probably the solver is killing some of the particles. Thank you.