Random error - animated Polyextrude

[royalize]

Hi all,

first, i want to say hello to everyone here. I´m relatively new to houdini and this is my first post.
While learning Houdini by rebuilding a lot of tutorials which are out there, i stumbled across a problem i can´t explain to myself how it could happen and how to eliminate it. 

I polyextruded some spikes based on an animated turbulent noise across a deformed sphere.
Now there are random errors/spikes while playback and also in cached files or even in an exported alembic file. 
The strange thing is, that the error is totally random. Never at the same frame oder place.

I attached some screencaps. Has anyone an idea to get rid of that error? Any suggestions would be very helpful. Thanks.

cheers 

T.

Btw, thanks to all of you who are recording all this cool and free tutorials, they are very helpful.

 

 

[Sean-R]

Could be your Normals? Might be worth giving them a check.

[f1480187]

It's a common issue with spikes. It occurs almost every time I use Poly Extrude or Poly Bevel or even Starburst procedurally. It happens with bad-shaped polygons, most of the time.

[konstantin magnus]

A workaround might be to first extrude inwards by a tiny bit an then move the extruded points along their normals.

normal_extrude.hipnc

[royalize]

Thanks, i will check that out tonight. 

What I found out yesterday was that this error only occurs if i scale the "Transform Extruded Front". If there is any other value then 1 it randomly happens while playback, Value 1 works perfectly fine. 

 

[emix941]

Hey there! Old topic, but looks like errors still occur in Houdini 18. Any ideas how to fix it? Or how to restrict Polyextrude with the mask dependency in mind. So only max given value would be allowed, without error aka spikes.