No error popup for me....
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Houdini Engine for Unreal » Houdini to Unreal Import issue: "No smoothing goup found"
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- sidenimjay
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I just tested with 20.5.445 / UE5.5.1 and the rubber toy with Compute Smoothing Groups on, and for the import, I turn off Recompute Normals and Tangents


No error popup for me....
No error popup for me....
Edited by sidenimjay - 2025年1月23日 14:41:43
Technical Discussion » Solaris Fails to Render Karma Pyro Material
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- sidenimjay
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further note to this, is if you want the aov_fire you MUST have smoke enabled, there is no fire mask without smoke. If you want smokeless fire and mask, you should map the control field of the smoke with the same values used in the fire settings,
Houdini for Realtime » Houdini Niagara Updates
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- sidenimjay
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getting this error when trying to write an hbjson file from the fluid_splat_walkthrough hipfile, you have to dig down into the hda to get the warning as it is not being promoted to the top level.
Edited by sidenimjay - 2021年3月13日 16:19:46
Technical Discussion » Rendering an Eye in Mantra
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- sidenimjay
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here is a link to a video and scene file that shows how to setup an eye specific shader:
https://vimeo.com/253524581 [vimeo.com]
its not too in depth but shows how to solve a tricky little issue with the clear lens and shadows…
https://vimeo.com/253524581 [vimeo.com]
its not too in depth but shows how to solve a tricky little issue with the clear lens and shadows…
Technical Discussion » How do I make the fluid stick to the surface?
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- sidenimjay
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Technical Discussion » Pushing FEM objects with Pyro
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- sidenimjay
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here is your file in h15.5 format…i noticed that the point order is different in h16 hence my note about the constraints….it seems the trunks are the only thing selected in h15.5 so the values you have work fine to hold it, in H16 the trunks and limbs were selected for constraints
Technical Discussion » Pushing FEM objects with Pyro
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- sidenimjay
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I tested your file in H16. i removed the popadvectbyvolumes, added a vector visualization to the sop vector field.
I also used a blast sop to isolate the velocity volumes. the volume wrangle was not doing anything useful so I removed it as well.
part of the problem is that the sopvectorfield dop is referencing primitives 0, 1 and 2. if you look at the primitive numbers on the reference sop, you will see that density is prim 0 , vel.x is 1 and vel.y is 2 so if you dont use the blast sop you need to change the primitive numbers parameter on the sopvectorfield dop to be 1,2 and 3 in order to capture the correct volumes for velocity. the vector field visualization dop will help you ensure you have the correct fields.
the other part, is the constraints are too strong, once I disable them the trees are affected by the volume velocity fields. currently the value is 1e+08 for the strength…i tried 1500000, at that is a bit too strong, but not strong enough to hold the base of the tree. you may need separate constraints for the limbs vs trunk if you want it to stick in place.
It is better practice to use 1 tree and a smaller fluid res to get the setup working so the turnaround is faster. then once the base network is sound, then start adding in other trees and upping the resolutions.
I also used a blast sop to isolate the velocity volumes. the volume wrangle was not doing anything useful so I removed it as well.
part of the problem is that the sopvectorfield dop is referencing primitives 0, 1 and 2. if you look at the primitive numbers on the reference sop, you will see that density is prim 0 , vel.x is 1 and vel.y is 2 so if you dont use the blast sop you need to change the primitive numbers parameter on the sopvectorfield dop to be 1,2 and 3 in order to capture the correct volumes for velocity. the vector field visualization dop will help you ensure you have the correct fields.
the other part, is the constraints are too strong, once I disable them the trees are affected by the volume velocity fields. currently the value is 1e+08 for the strength…i tried 1500000, at that is a bit too strong, but not strong enough to hold the base of the tree. you may need separate constraints for the limbs vs trunk if you want it to stick in place.
It is better practice to use 1 tree and a smaller fluid res to get the setup working so the turnaround is faster. then once the base network is sound, then start adding in other trees and upping the resolutions.
Technical Discussion » H16 fur and displacement
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- sidenimjay
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Kai,
this works great with a principled or classic shader…but doesnt seem to obey my custom shader with displacement using a displace along normals. I watched the shader master class and attempted to match the exports and options that may be on the principled or classic shader but still no success using a custom material displacement to drive the hair..perhaps i am still missing something
in the event that custom shaders are bit supported yet, if I am using a parameter to drive the displacement map or using udim to drive it, is there a way to apply that using the displace along normal parameter on the hair generate object?
this works great with a principled or classic shader…but doesnt seem to obey my custom shader with displacement using a displace along normals. I watched the shader master class and attempted to match the exports and options that may be on the principled or classic shader but still no success using a custom material displacement to drive the hair..perhaps i am still missing something
in the event that custom shaders are bit supported yet, if I am using a parameter to drive the displacement map or using udim to drive it, is there a way to apply that using the displace along normal parameter on the hair generate object?
Technical Discussion » H16 fur and displacement
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- sidenimjay
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Houdini 16.0.572 Added skin displacement to the hair generate object.
by default, the generated hair will now be displaced by the values set up on the skin shader, if it is a standard houdini shader with the expected values.
looks like this is the one we have been waiting for!
by default, the generated hair will now be displaced by the values set up on the skin shader, if it is a standard houdini shader with the expected values.
looks like this is the one we have been waiting for!
Technical Discussion » Being able to display and output different geometry in an hda
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- sidenimjay
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you need to set multiple outputs in the parameter interface and then use output sops to designate what sops you want to export
have a look at the collision source sop as an example of this method
other than this, I dont know of another way to display one node and export another
have a look at the collision source sop as an example of this method
other than this, I dont know of another way to display one node and export another
Technical Discussion » Hair / Fur groom weirdness on setting Length.
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- sidenimjay
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so as not to offend any fans, I will leave that to readers to choose their own least favorite rendering engine

Technical Discussion » Hair / Fur groom weirdness on setting Length.
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- sidenimjay
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you could always export from 557 back to 504.20 for the rendering…we have to do the same here to my least favorite 3rd party renderer…the bane of 3rd party rendering, it only works for the builds they give you…
Technical Discussion » Hair / Fur groom weirdness on setting Length.
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- sidenimjay
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this must not have been the same bug I was getting, though it looked like it at first.
looking at your file, it has something to do with the groom…if I bypass the groom, the set_length behaves normally
not sure exactly which operation in your Comb_brush is causing it…I wish strokes could be exposed to try to isolate the cause…
you could try re-grooming or just deleting the bad curves…would be good to send this to sesi support to see if they can find a bug in the code somewhere…
looking at your file, it has something to do with the groom…if I bypass the groom, the set_length behaves normally
not sure exactly which operation in your Comb_brush is causing it…I wish strokes could be exposed to try to isolate the cause…
you could try re-grooming or just deleting the bad curves…would be good to send this to sesi support to see if they can find a bug in the code somewhere…
Technical Discussion » Hair / Fur groom weirdness on setting Length.
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- sidenimjay
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Use the latest version 16.0.557… I am assuming that you are on windows…if so I reported this bug a while back and it has been fixed in this version
Technical Discussion » Rendering issues.
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- sidenimjay
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Technical Discussion » Rendering issues.
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- sidenimjay
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so it seriously sounds like this is an issue where your machine is going into swap and that is what is causing the increase in render time.
have you tried baking the sims out? that should help keep the render times to what they are when you start the renders
have you tried baking the sims out? that should help keep the render times to what they are when you start the renders
Technical Discussion » Rendering issues.
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- sidenimjay
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what is your ram usage doing as you render? it could be increasing to the point it puts the render into swap. the dopnets that are cooking during the sim will eat the ram you need to execute the render.
it is generally best practice to bake all sims to disk prior to rendering.
it is a mighty fine looking render I would love to see it in motion!
it is generally best practice to bake all sims to disk prior to rendering.
it is a mighty fine looking render I would love to see it in motion!
Edited by sidenimjay - 2017年3月23日 11:20:49
Technical Discussion » Rendering issues.
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- sidenimjay
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do you get the same behavior if you render without the waterfall?
are there potential spikes in the motion blur?
does the render time only increase or do some frames drop back down?
if you render the same later frame by itself is it still in the longer render time or does it render faster?
did you bake out the waterfall so it is only reading the data from disk or is it cooking the dops at the same time as the render? if it is, then it is possible you are beginning to swap which will increase render times as well…
are there potential spikes in the motion blur?
does the render time only increase or do some frames drop back down?
if you render the same later frame by itself is it still in the longer render time or does it render faster?
did you bake out the waterfall so it is only reading the data from disk or is it cooking the dops at the same time as the render? if it is, then it is possible you are beginning to swap which will increase render times as well…
Technical Discussion » Carve First U
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- sidenimjay
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Technical Discussion » Crowd Simulation : Maya - Houdini - Maya
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- sidenimjay
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As far as I know, the crowds are a mantra procedural. you can convert them to geometry but depending on your character poly count it is most likely going to be in the tens of millions of polys
I dont know of any renderer other than mantra that will efficiently render the crowd procedural.
I am using them now for a project that is being rendered in arnold from maya, but I am rendering them in mantra. motion blur lines up, but it has been a process to recreate all the environments in houdini.
I dont know of any renderer other than mantra that will efficiently render the crowd procedural.
I am using them now for a project that is being rendered in arnold from maya, but I am rendering them in mantra. motion blur lines up, but it has been a process to recreate all the environments in houdini.
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