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brokenpixel

.obj Import Groups Problem

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hello all

i am having an issue in regards to importing an .obj and dealing with groups. the breakdown -->

1) make simple geometry in maya (ex. a row of 4 spheres "pSphere1-4")

2) group aabove geometry - making "group1"

3) export .obj

4) import .obj via file SOP

5) apply shader to group via shader SOP (due to wanting to apply different shaders to different groups as the imported geometry gets complex).

what happens is that the first element in each group (ex. "pSphere1" from the row of 4 spheres) seems to be its own group (verified by MMB on the file SOP and checking the list of groups). it doesn't accept the shader. i thought perhaps that for some reason it was duplicated and the "grouped" version was there as well but a delete SOP culling out "pSphere1" just deletes it. this is all very odd to me due to the file SOP info saying that there are the correct number of primitives in "group1". is there some processing that needs to be done to correctly convert the groups created in maya to ones that work properly in houdini ?

clearly i am new at this game. any assistance would be greatly appreciated.

thank you in advance for any and all help !

scott

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It has to do with the way Maya writes the OBJs out AND/OR the way they are being read by Houdini. It's tough to say who's in the wrong here but I'm leaning towards Maya ;p

What Maya seems to do is automagicly create a point group for each object you are creating, that's where the psphere1 group comes from, inaddition to the groups you create.

Now if you look at your obj file by opening it in a text editor, you'll see a line like this...

g pSphere1 group1

That's the group specification for the first sphere. They inline two groups for it. Further down you'll see this for the second sphere

g group1 pSphere2

and for the third

g group1 pSphere3

The groups names switch order after the primary object in the group and Houdini apparently is only capable of reading the first one. The result is the first sphere gets grouped in pSphere1, and everything else gets grouped in group1.

As for how to fix it... Dunno. I tried deleting history and playing with the exporter options but the pShere groups persist. You could go in and edit the objs by hand, but it's probably easier to just fix them up in Houdini if you have a lot of groups.

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hello all

i am having an issue in regards to importing an .obj and dealing with groups. the breakdown -->

1) make simple geometry in maya (ex. a row of 4 spheres "pSphere1-4")

2) group aabove geometry - making "group1"

3) export .obj

4) import .obj via file SOP

5) apply shader to group via shader SOP (due to wanting to apply different shaders to different groups as the imported geometry gets complex).

what happens is that the first element in each group (ex. "pSphere1" from the row of 4 spheres) seems to be its own group (verified by MMB on the file SOP and checking the list of groups). it doesn't accept the shader. i thought perhaps that for some reason it was duplicated and the "grouped" version was there as well but a delete SOP culling out "pSphere1" just deletes it. this is all very odd to me due to the file SOP info saying that there are the correct number of primitives in "group1". is there some processing that needs to be done to correctly convert the groups created in maya to ones that work properly in houdini ?

clearly i am new at this game. any assistance would be greatly appreciated.

thank you in advance for any and all help !

scott

25452[/snapback]

make sure that you export with the "point group" option selected when exporting from maya. Houdini will pick that up in the group sop.

GY

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