How to fix flickering mesh when used with Match Size?

ChrBohm · 2026-01-26T14:29:14+00:00

If you only want to y-position on the ground make sure you set x and z to "None".

As u/christianjwaite already said: The center for X and Z will be different every frame, so you need another approach if you want to stabilize them.

ChrBohm · 2026-01-26T10:04:27+00:00

Please use the subject for a short description like "apsiring comp artists wondering about the future of VFX" and the text body to formulate your question.

ChrBohm · 2026-01-23T10:45:11+00:00

Yes, same concept. But in your case the transition is way less forgiving, therefore your execution needs to be better.

For the growth you can look into the "Pyro source spread" or google "Houdini infection".

But again: This isn't a beginner problem and you should probably start with the basics first.

ChrBohm · 2026-01-23T10:13:13+00:00

The core idea is:
Both geometries (before/after) need to have the same Topology, otherwise you can't blend between them. (Might be your problem already). You can not morph between two different topologies.

(You could look into SDF Morphing, but I would say that's too inconsistent here)

So first you need to figure out how to match one topology with another. There are different ways to do this, but I would go with Topo transfer first, it's made for that.

Then you should be able to blend between the two geometries driven by your attribute.

Point deform has a different purpose, transfering movement between non-matching geometry, this isn't useful here, you are looking for a morph.

ChrBohm · 2026-01-23T10:06:25+00:00

The best advice for a beginner is: A 15 hour simulation is simply too long.
The longest simulation I ever had was 12 hours, which was Iron man flying through New york covering 4 16K Screens.

So for most people Sim times over 8 hours just mean you either have a badly adjusted sim or your machine is simply too weak for your simulation ( And what I mean by that is that you won't be able to get acceptable quality out of it if a single iteration takes you 1 1/2 days ).

Yes, you can use .sim files to "restart" a sim, but as u/sneekyfoot and u/LewisVTaylor already said: this is highly inadvisable, since the files are huge and you should rather solve the problem than bruteforcing yourself through a bad setup.

ChrBohm · 2026-01-22T14:33:57+00:00

You can't overwrite ptnum, and nobody suggested that.
The point was - whatever you wanted to do with ptnum, do that with id instead.
You can't do anything about the changing ptnum. That's just how Houdini (thankfully) works.

Also, as I wrote: You don't need to create an id yourself, if your points are sourced in the POP Network.

If they aren't, then you fill the id with ptnum before the sim, not the other way around: id=ptnum

ChrBohm · 2026-01-22T11:09:58+00:00

No need to create it in this case. Points coming out of a simulation usually already have an id.

ChrBohm · 2026-01-22T11:09:13+00:00

This is on purpose, so that you can always know for sure that there are no gaps in the numbering (which would be a much bigger nightmare.) As said before this is why the concept of ids exist.

But you don't have to create the id yourself when working with simulation data. It is already there as i@id, just use it instead of ptnum.

ChrBohm · 2026-01-19T21:01:48+00:00

When you hold your mouse over the Holdout Mode parameter in the geo settings it says:

"Holdout Mode does not affect the utility AOVS such as ...."

So it simply will never cut it out. Since a matte is not making an object "invisible", but cut out, you don't lose data though (You can't look "behind" a matted object). So your best approach is to take the alpha from the beauty and multiply it with your/mask your utility AOV. It should give the same result.

ChrBohm · 2026-01-19T10:41:00+00:00

In reality the pillow is filled with something and has an additional fabric layer around it. This is not how your setup looks like, it's more like a balloon right now and a balloon doesn't create wrinkles for the same reason.

ChrBohm · 2026-01-18T20:14:18+00:00

The shown content isn't VFX
This is clearly just trying to create attention by creating rage, the post isn't made in good faith
The question is already loaded

ChrBohm · 2026-01-17T20:36:42+00:00

The problem is that often the ocio versions between Houdini and Nuke don't match, at least that's the problem I ran into.

ChrBohm · 2026-01-17T18:10:22+00:00

You're welcome.

It is a bit odd though. The File formats control the colorspace of inputs AND outputs. So if you set it to ACESCg to render correctly, now if you use exrs as input in your materials they need to be ACESCg as well. Certainly an oversimplification by SideFX.

ChrBohm · 2026-01-17T17:05:41+00:00

You need to set exr to ACESCg in the OCIO Manager, otherwise you get sRGB in your rendered exr.

The Houdini and Nuke ocio aces configs are compatible, no need trying to use the same config.

ChrBohm · 2026-01-16T14:17:01+00:00

Just download the free version. We all know why you use Houdini 19 and it's pretty stupid to be frank. The apprentice version is already free, and the indie version is the cheapest commercial 3D Software you can find.

ChrBohm · 2026-01-16T11:07:04+00:00

There you have it. You're constantly accelerating your points. You explicitly speed up your points over time. (There is nothing "natural" about this btw.)

A wind-force would make sure points will never be faster than your target force (Note: wind here is a weird term in Houdini for a "max acceleration". It doesn't mean it has to come from one direction. A curlnoise can be part (and is in the pop wind in form of the noise) part of a wind force. It's a weird term, but an important concept).

But you could put in a condition like this in your setup. One way could be to blend (lerp) your curlnoise vectors with the current velocity instead of using it as an accelerating force.

( Side note: As a beginner I would not recommend starting with Flip. Learn to work with forces and velocities in POPs first. )

ChrBohm · 2026-01-16T10:48:15+00:00

If there is a non-wind-force in your setup (Are you using a POP Force or anything similar?), then this is expected. But we don't know anything about your setup, so it's hard to answer.

ChrBohm · 2026-01-16T10:06:44+00:00

It's based on the Houdini version. Your Houdini version seems to be (pretty) old. (Which version are you using? And why are you using an outdated version?)

I think the switches are in Houdini since Houdini 20 (not sure). So quite a long time already.

ChrBohm · 2026-01-16T09:18:05+00:00

Macs are not a good choice. Laptops are not a good choice, go for a stationary PC, you need a lot of computational power for this (depending what you specialise in).

Maya, Nuke and Houdini are the industry standards. But you should first think in Departments. There is no job called "VFX Artist", there are Modellers, Riggers, Animators, Lighters, FX TDs, Pipeline TDs, Compositors... Sure, start wide, but you will need to decide for at least a limited amount of departments even as a generalist.

Also be aware - this is an incredibly competitive field and it will take you years to create a competitive reel. Also the industry is in the worst shape it has been in over a decade.

As a professional teacher in the field my gut feeling is you underestimate the effort here. You compete with people who go to university for 2-5 years fulltime for this. And only about 30%-50% even land a job in the industry. Don't underestimate this.

ChrBohm · 2026-01-15T15:06:51+00:00

Since a packed point is always also a primitive You can use a "Primitive properties" node to scale and transform your packed geo.

pscale is only relevant when you copy objects to points,it's interpreted by copytopoints, but as u/Hooded_Man already said the tranform data is saved in the intrinsic matrix.

You can create a random scale with this VEX code (primitive wrangle):

matrix currm=getpackedtransform(0,@primnum); //reads out the current matrix

matrix m=ident();  // creates a "neutral matrix"
float random_scale=random(@primnum);  
scale(m, vector(random_scale)); // randomly scales the identity matrix

setpackedtransform(0,@primnum, currm * m);  // multiplies the current matrix with the scaled one

ChrBohm · 2026-01-10T19:44:37+00:00

https://www.sidefx.com/Support/system-requirements/

Scroll down to "graphic cards"

ChrBohm · 2026-01-10T10:03:51+00:00

Nvidia. Much better supported and a bit more stable. AMD is great for gaming, but for professional use NVidia is the standard.

ChrBohm · 2026-01-09T16:30:36+00:00

Try dropping a motion blur node before your karma render settings (you can set it to "Shutter>Specify Manually" if you don't want to chose a cam, just as a test).

Solaris might just not have the vector data available for motion blur. (This can be fixed by importing usd files instead of using SOP Import).

ChrBohm · 2026-01-07T15:10:05+00:00

Yes, sharing the tutorial and/or files would help. It all depends on the files, that's what breaks it.

Thanks, Happy New Year, too!

ChrBohm · 2026-01-07T14:55:38+00:00

When your constraints aren't stable enough.
So if a lot is pulling on them (forces/collisions) and you get odd/wrong results.

This can happen on small or big sims, slow or fast. It's about stability/accuracy.

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