Creating particles from objects that started out as NURBS?

Forums Technical Discussion Creating particles from objects that started out as NURBS?

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rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 12, 2009 5:32 p.m.

I prefer NURBS for doing most of my modeling since I like to make curvy, abstract shapes. I have made some models in MOI and then converted to poly (tried this both in silo then exported to houdini and directly in houdini). Now I am trying to create particles from these objects and it just doesn't seem to be taking.. it will go on for minutes but never finish.

These shapes aren't really all that complex, I kept them fairly low poly but it seems that houdini is having some trouble with objects that started as NURBS.. is there any sort of work-around for this, has anyone else had a problem like this?


Soothsayer: Member; 875 posts; Joined: Oct. 2008; Offline

Aug. 12, 2009 10:07 p.m.

Have you tried nurbs geometry created inside Houdini? That works fine, even if you mix with polygons. Try appending a convert SOP and see if that alleviates the problem.

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rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 13, 2009 1:15 a.m.

I can't model effectively in houdini, its just not set up like a true NURBS modeler, I've literally tested doing something in houdini versus the other program and it takes me a lot longer in houdini to do the same thing.. I guess I can do this for simple objects but this is definitely a drawback since this problem also occurs with a solid body object sometimes that is nurbs as well it seems.

edit: well I guess as a last resort I can import the models as just curves and then loft them in houdini in hopes that this will work, would love to hear from anyone else who has had this issue.


ragupasta: Member; 349 posts; Joined: Aug. 2006; Offline

Aug. 13, 2009 5:09 a.m.

post a file if you can, and we can see if we get the same problem as you.


rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 13, 2009 3:29 p.m.

thanks for the help.. I have posted 2 files that I imported as geometry, an igs and an obj file.

http://siliconvalley1-odesk.s3.amazonaws.com/bowl.obj [siliconvalley1-odesk.s3.amazonaws.com]
http://siliconvalley1-odesk.s3.amazonaws.com/bowl.igs [siliconvalley1-odesk.s3.amazonaws.com]

(click “save as” when the page comes up as it will save it as the file format)


rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 14, 2009 4:01 a.m.

I'm finding the same issue with NURBS models created from other software programs now too.. I downloaded the Rhino trial and created a few simple models and they also won't convert to particles in houdini.

I think this is a legitimate issue.. I find it hard to believe that people are doing all their modeling in houdini, there must be some solution to this.


Soothsayer: Member; 875 posts; Joined: Oct. 2008; Offline

Aug. 14, 2009 4:28 a.m.

I haven't tried the other one but I can emit particles from the bowl.obj file without problems.

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Soothsayer: Member; 875 posts; Joined: Oct. 2008; Offline

Aug. 14, 2009 4:34 a.m.

maybe that helps. (point the file sop to the igs file)

Attachments:
NURBS.hipnc (54.6 KB)

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rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 14, 2009 4:36 a.m.

I'm trying to turn the object to particles, not emit… more useful though was that I wanted to use these objects are rigid bodies within particle simulations which doesn't seem to be working either.

thanks for the help in figuring this out


Soothsayer: Member; 875 posts; Joined: Oct. 2008; Offline

Aug. 14, 2009 4:46 a.m.

Like this?

You could also instance them.

Attachments:
NURBSb.hipnc (56.2 KB)

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ragupasta: Member; 349 posts; Joined: Aug. 2006; Offline

Aug. 14, 2009 5:09 a.m.

Works ok for me on both geometrys. Both have been turned into particles. And the geometrys should be inside the fileSOPS.

Cheers

Attachments:
nurbs.hipnc (226.4 KB)


rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 14, 2009 5:16 a.m.

Thanks, so I guess its the copy sop thats making this work? it doesn't load the geometry since yours was in a different place so I am going to set it up right now and test on my machine.


rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 14, 2009 5:22 a.m.

I took a look at the file after inserting the geometry.. not sure what this is but what I am trying to do is use the shelf tool called “particle fluid from object”


ragupasta: Member; 349 posts; Joined: Aug. 2006; Offline

Aug. 14, 2009 5:49 a.m.

You said you wanted the geometry turned into partilces, not particle fluids

No worries, still it works for me with particle fluids as well. I used the shelf tool for making fluid for object.

Attachments:
nurbs1.hipnc (803.6 KB)


rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 14, 2009 5:55 a.m.

Thanks for posting this.. so its the transform SOP then that is making this work I think? I am going to look the sop up right now


ragupasta: Member; 349 posts; Joined: Aug. 2006; Offline

Aug. 14, 2009 6:14 a.m.

The transformSOP is there because the imported model was way too large. It was about couple of times the size of the perspective grid. Remember a unit in Houdini is set to meters in scale. The transformSOP has no effect on turning this into particle fluids.

Are you sure you are using the shelf tools right?

Click particle fluid from object,
Select the gemoetry container, or drag select all the geometry in the viewport, and hit enter. Or after selction right click in the viewport and seclect “accept selection”.


rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 14, 2009 6:18 a.m.

Yeah I'm sure I'm doing it right, I already have learned a lot about particles and have done this with objects that started out as poly and it works fine.

I am wondering what your system specs are (ram, processor).. I wonder if my computer is too slow or something but it has 8 gb ram, 64 bit system.. this problem is strange.


rdane1010: Member; 120 posts; Joined: July 2009; Offline

Aug. 14, 2009 6:25 a.m.

After trying this again with the transform it seems to be working.. you are right about the scale being huge so I think that was causing the problem.. I had been using the scale tool but I think that must be different than using the transform tool so it was still too big to work..

thanks for the help, I am going to play around with this more to see if it works for other models.


ragupasta: Member; 349 posts; Joined: Aug. 2006; Offline

Aug. 14, 2009 6:28 a.m.

Glad to hear you got things working out fine. 8)

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