Hello,
I'm new to Houdini (again) and using the apprentice version 9.5.170. I ran into some problems when import/exporting models between Houdini and Maya regarding the UVs being all split up. Perhaps I'm just doing it incorrectly. Details below.

PROBLEM:
Houdini breaks up UV borders when importing and subsequently exporting polygonal geometry. This makes working with other programs difficult.

EXAMPLE:
Export a polyCube primitive from Maya to an OBJ format. We get 8 vertices and 14 UVs. All UV borders are ‘sewn’ together. The OBJ file looks like this:


# Maya cube primitive OBJ file. Notice only 14 UVs:
#
g default
v -0.500000 -0.500000 0.500000
v 0.500000 -0.500000 0.500000
v -0.500000 0.500000 0.500000
v 0.500000 0.500000 0.500000
v -0.500000 0.500000 -0.500000
v 0.500000 0.500000 -0.500000
v -0.500000 -0.500000 -0.500000
v 0.500000 -0.500000 -0.500000
vt 0.000000 0.000000
vt 1.000000 0.000000
vt 0.000000 1.000000
vt 1.000000 1.000000
vt 0.000000 2.000000
vt 1.000000 2.000000
vt 0.000000 3.000000
vt 1.000000 3.000000
vt 0.000000 4.000000
vt 1.000000 4.000000
vt 2.000000 0.000000
vt 2.000000 1.000000
vt -1.000000 0.000000
vt -1.000000 1.000000
g pCube1
f 1/1 2/2 4/4 3/3
f 3/3 4/4 6/6 5/5
f 5/5 6/6 8/8 7/7
f 7/7 8/8 2/10 1/9
f 2/2 8/11 6/12 4/4
f 7/13 1/1 3/3 5/14


Import the OBJ cube into Houdini using a file SOP, do nothing to it and re-export it using another file SOP. Logic would denote that it should result in an identical cube, but it does not. Instead, we get a poly cube with 8 vertices, and 24 UVs. Each face's associated UVs have been ‘split’ from the surrounding faces. The OBJ file looks like this:


# Maya cube primitive as exported from Houdini. Notice 24 Uvs:
#
g
v -0.5 -0.5 0.5
v 0.5 -0.5 0.5
v -0.5 0.5 0.5
v 0.5 0.5 0.5
v -0.5 0.5 -0.5
v 0.5 0.5 -0.5
v -0.5 -0.5 -0.5
v 0.5 -0.5 -0.5
vt 0 0 0
vt 1 0 0
vt 1 1 0
vt 0 1 0
vt 0 1 0
vt 1 1 0
vt 1 2 0
vt 0 2 0
vt 0 2 0
vt 1 2 0
vt 1 3 0
vt 0 3 0
vt 0 3 0
vt 1 3 0
vt 1 4 0
vt 0 4 0
vt 1 0 0
vt 2 0 0
vt 2 1 0
vt 1 1 0
vt -1 0 0
vt 0 0 0
vt 0 1 0
vt -1 1 0
g pCube1
f 1/1 2/2 4/3 3/4
f 3/5 4/6 6/7 5/8
f 5/9 6/10 8/11 7/12
f 7/13 8/14 2/15 1/16
f 2/17 8/18 6/19 4/20
f 7/21 1/22 3/23 5/24


How do I prevent this from occurring?
-Modulok-