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Everything posted by nicoladanese

  1. Hey! I'm trying to replicate an fx like this one, flip fluid (water in my scenario) creating a vortex...just wondering if anyone has an idea on where to start from, examples, hints... thanks a lot!
  2. Hey! I'm trying to cull out voxels that are out of the camera frustum (plus a little bit more for shadows sake) to save simulation time and increase details where needed, I found some examples for particles but nothing for volumes / pyro any help would be really appreciated! cheers
  3. Hey all! I need to start an fx of a waterfall that looks like the image attached. I'd like to get ideas on how to approach it, I think there is no need of meshes but just lots of points...
  4. great stuff! definitely something to get started thanks a lot! about advecting particles with fluid I fell into this video and reading comments is all about a low res fluid with millions of particles advected by it, motion looks very natural! I think I'm going to start with it!
  5. Hi all! I'm doing some research on rendering pyro explosions, and here's the result of my comparison between mantra on houdini and renderman 21 on maya using a vdb cache from a pyro explosion. https://vimeo.com/218752467 my thoughts I'm pretty happy with both of them, fire looks detailed as I expected from the hi res sim, and I like the way the light scatters through the smoke and lit it. renderman version came out "hotter" in terms of color than the mantra one, but I guess is something to do with the way blackbody radiations infos were passed to the emission component of the shader, so I can probably get closer one to the other by remapping values in a slightly different way mantra pros render the explosion with mantra was fast in terms of setting up the scene, and the shader is much easier to play with. It's also nicely setup when you create the pyro sim, so you can get a nice looking fire in a few click. cons I found render time slower than renderman, and I couldn't find a way of getting rid of the huge amount of noise in the meshes lit by the explosions (especially when the core of the explosion is brighter) , although my render settings are pretty high (I think): pixel samples 9/9, min/max ray samples 1/9 with noise level 0.005, diffuse and volume limit 5 renderman pros I managed to get faster frames with less noise on the surrounding environments cons set up the shader was kind of a pain compared to mantra. I needed to import fields and remap some values to make them work with PxrBlackBody, nothing too complicated but far more slow compared to mantra I'd really like to get feedback, ideas, personal experience or anything you'd like to say about it
  6. hey Heribert! thanks for your reply I tried min/max samplese to 3/9 and diffuse quality 10, definitely got rid of 90% of the noise, but the render time went from 25 minutes to more than 3 hours and a half! too bad you end up spending most of render time rendering the environment rather than the fire itself...I wonder if there's a smart way of converting the fire into something a little simpler to lit the env without using the actual fire cache...some kind of emissime mesh tinted with the color of the fire...
  7. Hey I'm wondering if there's a way of preventing houdini to go back to frame 1 when I interrupt a flipbook, I quite often launch flipbook to check sims and then stop to look at the sim from different perspective. I know I can write the cache but if there's a setting to avoid that it would be great I think... cheers
  8. hey Jesper/Diego thanks for the multiple suggestions, for my specific case I ended up using multiple boxes as sink volume to remove density!
  9. hey Jesper thanks for your reply, I had a look at your example, but it seems to me like this solution is good for rendering, but not for simming. I think I need something that lives inside the DOP of my pyro, maybe a hack on the Gas Resize Fluid Dynamic operator to cull the density fiels where I don't need it
  10. Hey all! I'm doing a pyro sim of a wheel burnout for a car drift, at the moment I'm emitting from the tyre, but I'd like to emit more from specific area (see attached image) , I mean I'd like to control more the areas of emission, considering the fact that obviously the tyre is rotating... any idea/suggestion ? cheers!
  11. great! thanks again very appreciated!
  12. in fact using a group node and the box as bounding box for the group solved the issue! thanks again for your suggestion! Now one good thing to add would be a blur so the emission density fade out instead of being high or low...
  13. Hey Dominik! thanks for your reply, your hip file is absolutely clear! only problem is I'm getting a bunch of error when I open it, and as a result it's only reading the low emission value. I suppose the issue is in the groupCombine as I have 0 points in "more" group, so no points are emitting more density P.S. I'm using H 15.5
  14. Hey All! I'm trying to write out some vdb caches from a pyro sim. As long as I plug the DOP Import into a VDB convert and then into a file everything looks great and I get my density for render. Problem is, now I want to write out velocities of the volume so I can later import it in a fresh scene to advect some particles. I can't find a way to enable the DOP import to get the velocity, so I'm plugging the DOP I/O which has all the field I need. BUT the cache is getting much much heavier in terms of disk space. I am writing out 4 scalar fields (density vel.x vel.y and vel.z) so I'm expecting the cache to be roughly 4 times bigger, but in my case frame 10 was around 2 Mb and now is 240 Mb any one with some ideas? Thanks in advance! here some screens of how I'm setting this
  15. Hey Gavin, you mean to get the velocity grid only where I have density above 0? any idea how to achieve that?
  16. Hi Anthony, thanks for your reply! you were right, the voxels for vel are basically filling up the bounding box of the volume in a few frames (I guess the reasons are collisions with geos) , while the density is very limited (I've attached 2 images for comparison) Now I'm looking for a reasonable way of getting the velocity info without filling up the disks! I guess I can VDBresample vel field before writing it out to maybe a 10 times lower resolution field grid so I get the velocities I need , although I'm not getting the fine details...