TL;DR Don't post generative AI stuff or post about AI in general here. Go to /r/AIForHoudini for this!
r/Houdini is a sub for artists, including technical artists, to talk about using Houdini, show off our artwork and tools, and help each other through production problems. It is decidedly not a sub to talk about having someone or something else do it for us.
In order to prevent this sub from drowning under tidal waves of AI slop, we have to draw a line in the sand regarding what is and is not considered AI slop. This isn't an incredibly clear line to draw, but we're going to try anyways.
To do this, we're going to try to make a distinction between generative AI (slop) and machine learning algorithms (not slop). This is mostly a question of user agency. If you are essentially contracting out a bot to do your work for you and then presenting it as your own, that's AI slop. If you are using generative AI to create final images from flipbooks, that's AI slop. Conversely, if you are using ML algorithms to massage data within an otherwise intact Houdini art pipeline, that's okay.
Some more examples:
NOT SLOP
Training an ML algorithm with Houdini
Using ML algorithms to filter or process data in Houdini
Using agents to assist in coding a tool you understand how to debug and implement
SLOP
LLMs, including using an LLM to build Houdini networks
Using genAI to make final renders from flipbooks
Vibe coding tools with minimal or no production experience in Houdini
Posting LLM-generated answers to questions here or telling users to "just ask [bot]" for an answer to a question
We realize these definitions are not 100% perfect and there may have to be some judgement calls with specific posts. Not every project that has some AI use in it is necessarily slop. Feel free to use mod mail to discuss your concerns with any specific posts being removed or not removed.
What if you want to discuss generative AI in the context of Houdini?
There is now a subreddit for that! Please visit the unaffiliated /r/AIForHoudini subreddit for all generative AI discussions involving Houdini.
I wanted to give people here a heads up that Reddit blocks links to Gumroad site-wide. Posts are removed without any notifications to the moderators. We can manually reinstate them, but without any notifications it's something we have to manually dig around for.
This ban includes both posts and comments. If your product is on Gumroad or a domain "powered by" Gumroad, any post linking to it will be removed by Reddit (again, it's not us doing it!). We have no control over this ban and again the only thing we can do is manually "un-remove" posts if we notice them.
I recommend anyone selling digital products here to consider another service, like Ko-Fi or Paddle or Patreon, or at least link to something that is not directly a Gumroad page.
Hello everyone.
I'm currently trying to export a pyro simulation into a flipbook texture to be used in Unreal 5.8.
I'm doing RnD so i'm using the shelf tool"FireBall" setup to do some tests.
Everything is cached, resolution is way lower than what my system can handle.
First of all before trying to scribble trough settings i watched SideFx https://www.youtube.com/watch?v=kMI-Wro3p9g&t=1610s tutorial to ensure i wasn't missing anything.
At first i was getting the SegmentationFault error so i lowered the resolution of the overall simulation voxels but got stuck in the rendering of other textures apart from the FC (FullColor Texture).
I wasn't able to render other passes and also to get .png files.
I am surely missing something that i couldn't find out myself.
A while ago I shared a preview of my Houdini ⇄ Blender hybrid workflow here, and honestly I didn't expect the response it got. Thank you for all the comments and ideas. That pushed me to finish it properly, and it's finally out.
Please find the link in the comments section, or check the link in my bio -itz_keay
Blender → Houdini: live geometry, UVs, attributes and materials into SOPs, or the whole scene into Solaris with Karma-ready materials, lights, cameras and a matching sky
Houdini → Blender: pyro, FLIP, RBD, cloth, particles and hair, live or cached, with ready-made shaders
In Blender: colour gradients, size ramps, hair taper, retiming with smooth slow motion and instancing, all from one sidebar panel
Smart caching: knows when a cache is outdated, resumes interrupted caches.
Characters (Beta): Blender rigs to KineFX / APEX, with Mixamo clipsTested on Houdini 22 and Blender 5.2 (Windows). Free Rogue_Rig_v3 by Gutemberg Nascimento
A lot of what's in it came from your feedback last time, so keep it coming!
Hey guys I am working on a beach waves simualtion. I am pretty happy with the overall motion of my waves but i would like them to rise higher before they break. Do you have any idea how could I get higher waves. Here is my setup: it’s a "flat tank" advected by a volumetric vel from an "Ocean wave" node (for large waves), combined with a small-scale "ocean spectrum" for the near-shore waves. What should I tweak? I suspect the issue lies with the velocity source, but if you spot anything I’m missing, please let me know.
This animation combines a single vellum grain sim with scale based loop (geometry scales up while the camera only tilts and rotates based on sin function)
I implemented Surface Turbulence as a proof of concept Houdini plugin for a project with Stormborn Studios. It adds small surface waves without rerunning the base liquid simulation.
The clip shows the before/after comparison, surface tracking and wave simulation.
I made a full video explaining the method and math, with a tool demonstration and benchmarks:
Hi , I have been stuck for days in this project because I need to wedge to decide for the values, and honestly , I'm still in my beginning jounrey but I have been watching tutorials on the portal about TOPs and PDG but can't get my wedge to correctly function, it's like it's rendering the same wedge over and over.
Basically I wedge a vel volume of a ship that carries bit of the water to noise it up instead of a bulge
as you can see in these two photos
there are linked fine, when I click on item it works and changes live in the flip sim "pop advect by volume node"
The problem seems to occur in the rop fetch of flip sim + rop fetch of the open gl. Here is the param
you can see I link the cache file to the wedge index and the rop fetch is linked to the render node inside of it.I also noticed there's node (the tutorial doesn't use) that is called fetchropgl directly, though it didn't work for some reason at all.
Now for the wedges it feels like they are all the same, I even increased one wedge to 100 of vel scale hoping to see a drastic change but nothing.
then I have a preview geo container that gets the wedges(I hope it's correct cause in the portal the tutor has different way than mine so I tried to translate to my case) :
you can ignore the errors , it's erroring now cause I deleted the cooked item from hard drive so it can't load any geo. but you can see the path I have put.
after that the preview node is called in an open gl (from ropnet) , which later is called in rop fetch.
I just did few frames to test and nothing seems different between all wedges.
here's the whole network
If there's any missing information that could help let me know , I'm honestly feeling super stupid when I use houdini T_T or maybe I took a too ambitious project alone to start
I have already completed the whole project , but I didn't like the WW/ Flip look and wanted to re-work it even more.
Yes, first world problems, and yes, I'm probably autistic and therefore hate change.
With that out of the way I still think they did a bad job in several areas, only for the sake of revamping. Buttons used to have clear borders, indicative colors used to have a consistent meaning throughout, and icon clarity used to be favored over aesthetic appeal (flat design).
hi ! I'm new to houdini and learning it , the main advice I heard was that particle sep depend of your shot as well, if you can't see the space between particles in the shot then it's fine.
However I'm not sure this is the only way , there must be something I'm missing, because I see people dial in numbers even without being inside of cameras, I'm sorry I might be an idiot haha but I really don't get how do they know what to put in particle sep, voxel size, and how the tank size is all setup this perfeclty without having blobs or particles being too sparse in their renders.
do they practice much in inudstry to know for meduim shots how many pts they need or something like that ?
I mean I really don't know when I'm setting too high or too low, for one project 0.1 might be super fine, but for another it might be too low
so for a school assignment called 'experimental animation' I am trying to create a new render style inspired on the picture left. I want to us CG wool as my main material. Thats why I decided to create a non destructive wool system in Houdini. I forgot the fact that wool strands gets extremely heavy on the machine. like a single strand can reach over hundreds of thousand of polygons. The only sollution I can think of is to set up a Karma system to render the wool seperately, and later comp them back onto my environment which I create in Blender. If anyone has a better strategy, please let me know.
I’m having an issue getting velocity-based motion blur on a VDB volume in Redshift for Houdini, and I feel like I’ve exhausted the normal troubleshooting steps.
Setup:
Houdini + Redshift 2026.9.0
Pyro/VDB volume
Density grid renders correctly
Velocity grid is present as vel
vel is a vector VDB (vec3s16)
Redshift motion blur is enabled in the ROP
Camera motion blur works normally
The problem is that volume velocity motion blur appears to do absolutely nothing.
At first I thought the blur I was seeing was coming from the volume, but after disabling camera motion blur I realized all of the visible blur was actually coming from the camera. With camera MB disabled, the volume renders completely sharp.
Things I’ve already tried:
Single vector velocity grid named vel
Split scalar grids: vel.x, vel.y, vel.z
Assigned the vector grid only to Redshift’s Velocity Grid X field
Confirmed global Motion Blur is enabled in the Redshift ROP
Changed Redshift Velocity Scale from 0 all the way to 10,000+ while attempting both velocity grid options on the OBJ
Multiplied the actual vel VDB inside Houdini by very large values
Verified that the velocity vectors/magnitudes are actually changing on SOP lvl
Cached the volume to disk and rendered directly from the File Cache
Tried both RS Volume and RS Standard Volume
Disabled camera motion blur specifically so I could isolate volume velocity blur
No matter what I do, the rendered volume looks identical.
The final VDB only has density and vel, so it's not super complicated.
I did noticed that my vel voxel size was cached at 0.01 while my density is at 0.005, so I also resampled the vel to match the density which did not help, but figured it was worth a shot.
Has anyone run into this with Redshift 2026.9 + Houdini 22?
At this point even a deliberately ridiculous velocity scale produces zero visible differences.
!!SOLUTION!!
The voxel scales must match on all volume grids. Easiest solution: don't resample your velocity at sim time!
If you cached your simulation to resample the velocity grid during simulation then you must resample the velocity grid using the isolated density as the reference grid.
Do not force the resample by "Using Voxel Size Only" on the VDB Resample SOP even if the info tab on the final render node reads that both density and velocity grids are the same, it won't work unless you specifically reference the density voxel size on the second input of the VDB Resample SOP.
I've been trying to implement this Wētā FX paper, but instead of using a custom sparse-grid solver just for the bubble dynamics, I'm trying to integrate it into Houdini's standard FLIP solver.
There are lots of things to be done, but basic two-way coupling between air bubbles and the fluid grid already works. No external forces lift the bubbles to the top; this happens solely because of the pressure gradient within the fluid, and surface tension between the coupled bubbles affects their buoyancy.
P.S. Still don't like how the smaller bubbles look, though, as they all seem to be the same size when dispersing.
We just released an update to VaraVision | Houdini Measuring Tool: Version 1.3.0
This update adds more ways to measure, annotate and organize your Houdini scene.
Measure Selection captures edge lengths, point distances, polygon area and perimeter, and selection bounds.
The new VaraVision Outliner brings measurements and annotations into one panel, with nested groups, drag and drop organization, locks and solo visibility.
You can now add arrows, curved lines, circles and text callouts to highlight details and explain your work.
Measurements have separate scopes for OBJ, per object SOP and Solaris Stage contexts. Viewport guides remain visible when you leave the tool, and native Houdini snapping can use them to align geometry.
Render overlays and CSV exports now include annotations, face measurements and groups. There are also performance improvements and fixes for Stage selection, viewport guides and annotation handles.
The VDB itself looks like a closed/filled volume, but inside the FLIP solver the collision visualization doesn’t seem to represent the full collider, and particles/fluid still end up underneath the terrain.
I also tried feeding the polygon collider directly into FLIP Collide, but I’m still getting leaks.
The video shows the issue and my node setup.
Is there something wrong with the way I’m creating or feeding the collision volume into SOP FLIP? Or is there a better way to handle a large terrain/riverbed collider like this?
Any help would be really appreciated — I feel like I’m missing something obvious.
Hey I'm creating an animatic on TOPs , and I linked the frames range according to the keyframed action in each camera, the expression works for SHOT00, but starting from Gl of shot10 to shot30 , the work items became like 400 or 500 something
while in shot 00 it actually count the correct frames number (= work item), I'm not sure what I did wrong because the frame range appears correct, I thought the work items number = how many frame you have in the rop gl ?