Hi!

Can I import the smoothing groups included in an .obj file into Houdini?

Thanks for any help

Simplest way to find out is export the obj and load it into Houdini. You'll have your answer in 2 minutes.

Of course I tried that. Sorry for being unclear. Houdini seems to be ignoring smoothing groups data in my .obj files. Is there a way to retrieve the smoothing groups?

I don't think the obj format supports smoothing groups…

make the smoothing groups just regular groups to get them across…

HTH

Thanks for the suggestion, I'll give it a try but obj format does support smoothing groups via vertex normals as far as I know. Here's the .obj output of the same box, with and without smoothing respectively. They have pretty different vertex normals data and they show different smoothing groups when imported back into a program other than Houdini.


# Wavefront OBJ exported by MilkShape 3D

v -20.000000 20.000000 20.000000
v -20.000000 -20.000000 20.000000
v 20.000000 20.000000 20.000000
v 20.000000 -20.000000 20.000000
v 20.000000 20.000000 -20.000000
v 20.000000 -20.000000 -20.000000
v -20.000000 20.000000 -20.000000
v -20.000000 -20.000000 -20.000000
# 8 vertices

vt 0.000000 1.000000
vt 0.000000 0.000000
vt 1.000000 1.000000
vt 1.000000 0.000000
# 4 texture coordinates

vn -0.666667 0.666667 0.333333
vn -0.408248 -0.408248 0.816497
vn 0.408248 0.408248 0.816497
vn 0.666667 -0.666667 0.333333
vn 0.666667 0.666667 -0.333333
vn 0.408248 -0.408248 -0.816497
vn -0.408248 0.408248 -0.816497
vn -0.666667 -0.666667 -0.333333
# 8 normals

g Box05
s 1
f 1/1/1 2/2/2 3/3/3
f 2/2/2 4/4/4 3/3/3
f 3/1/3 4/2/4 5/3/5
f 4/2/4 6/4/6 5/3/5
f 5/1/5 6/2/6 7/3/7
f 6/2/6 8/4/8 7/3/7
f 7/1/7 8/2/8 1/3/1
f 8/2/8 2/4/2 1/3/1
f 7/1/7 1/2/1 5/3/5
f 1/2/1 3/4/3 5/3/5
f 2/1/2 8/2/8 4/3/4
f 8/2/8 6/4/6 4/3/4
# 12 triangles in group

# 12 triangles total



# Wavefront OBJ exported by MilkShape 3D

v -20.000000 20.000000 20.000000
v -20.000000 -20.000000 20.000000
v 20.000000 20.000000 20.000000
v 20.000000 -20.000000 20.000000
v 20.000000 20.000000 -20.000000
v 20.000000 -20.000000 -20.000000
v -20.000000 20.000000 -20.000000
v -20.000000 -20.000000 -20.000000
# 8 vertices

vt 0.000000 1.000000
vt 0.000000 0.000000
vt 1.000000 1.000000
vt 1.000000 0.000000
# 4 texture coordinates

vn 0.000000 0.000000 1.000000
vn 1.000000 0.000000 0.000000
vn 0.000000 0.000000 -1.000000
vn -1.000000 0.000000 0.000000
vn 0.000000 1.000000 0.000000
vn 0.000000 -1.000000 0.000000
# 6 normals

g Box05
s 1
f 1/1/1 2/2/1 3/3/1
f 2/2/1 4/4/1 3/3/1
s 2
f 3/1/2 4/2/2 5/3/2
f 4/2/2 6/4/2 5/3/2
s 1
f 5/1/3 6/2/3 7/3/3
f 6/2/3 8/4/3 7/3/3
s 2
f 7/1/4 8/2/4 1/3/4
f 8/2/4 2/4/4 1/3/4
s 3
f 7/1/5 1/2/5 5/3/5
f 1/2/5 3/4/5 5/3/5
f 2/1/6 8/2/6 4/3/6
f 8/2/6 6/4/6 4/3/6
# 12 triangles in group

# 12 triangles total