Export OBJ

Avex

Hi

I'm new here, and I don't speak english as my natural language, please forgive my mistakes. Google works but not always.

I have a doubt about export in OBJ format.

I try to work in TopMod importing files from SketchUp but doesn't work.

When I export or save an archive in OBJ format from TopMod the format is like this:

v 1 1 -1
v -1 1 -1
v -1 1 1
v 1 -1 1
v 1 -1 -1
v -1 -1 -1
v -1 -1 1
v 1 1 0.5
v 0.5 1 1
v 1 0.5 1
# 10 vertices

f 4 5 1 8 10
f 5 6 2 1
f 6 7 3 2
f 7 6 5 4
f 8 1 2 3 9
f 9 3 7 4 10
f 10 8 9
# 7 faces

(Opening it with notepad)

And I can import it into SketchUp (With OBJ importer rb) without problems.

But when I export the file in OBJ format from SketchUp, the format is:

# Alias OBJ Model File
# Exported from SketchUp, (c) 2000-2006 Google, Inc.
# File units = meters

mtllib cube2.mtl

g Mesh1 Model

usemtl FrontColor
v 0 0 -2
vt 0 78.7402
vn 0 -1 0
v 2 0 -2
vt -78.7402 78.7402
v 2 0 0
vt -78.7402 0
v 0 0 0
vt 0 0
f 1/1/1 2/2/1 3/3/1 4/4/1 

vn 0 0 -1
v 0 2 -2
v 2 2 -2
f 2/3/2 1/4/2 5/1/2 6/2/2 

vn -1 0 0
v 0 2 0
f 1/3/3 4/4/3 7/1/3 5/2/3 

vt 78.7402 0
vn 0 0 1
v 2 1 0
vt 78.7402 39.3701
v 1 2 0
vt 39.3701 78.7402
f 3/5/4 8/6/4 9/7/4 7/1/4 4/4/4 

vt 78.7402 78.7402
vn 1 0 0
v 2 2 -1
vt 0 39.3701
f 6/8/5 10/7/5 8/9/5 3/4/5 2/5/5 

vn 0 1 0
vt 39.3701 0
f 7/4/6 9/10/6 10/6/6 6/8/6 5/1/6 

vt 55.6777 0
vn 0.57735 0.57735 0.57735
vt 83.5165 48.2183
vt 27.8388 48.2183
f 8/11/7 10/12/7 9/13/7

And both are the same

Then, when I try to import the OBJ file into TopMod, apparently is not recognizable. The program freezes and finally at long last, crashes and shuts.

I have tried to modify the text and the order but doesn't work.

PLEASE! IS VERY IMPORTANT FOR ME. IT'S FOR MY DISSERTATION PROJECT. It's driving me mad.

My name is Juan Manuel Maldonado, I'm from Colombia . I'm a student of architecture and I'm in the last six months of study.

I have spent much time in these forums and there is much that I have learned thanks to all of you.

As I say yet, forgive my english, I believe that is awful.

Lot of many many thank you very much hehehe

remus

Not entirely sure about the intricacies of the obj format, but i think your best bet would be to import the skp file in to another application and try exporting it from there.

If you ask very nicely, solo (of these forums) might be willing to convert it for you. He has a rather nifty program called 'deep exploration' thats very good at converting files.

p.s. sorry for turning you in to a file conversion service solo, but youre the only person i know who has deep exploration. again, sorry.

Anssi

Avex,

Have you tried using some different options from the Export Options pane (opens from the Options button in the right bottom corner of the Export File dialog box).

There seem to exist several variants of an OBJ file. The only app I have tried exporting to was an old version of Poser, and that had its quirks too, and checking the "Triangulate all faces" finally worked.

Anssi

Avex

This is the response I got in the TopMod forums. Share it with you.

Thanks for everything.

@unknownuser said:

Juan,

TopMod does not have the ability to import non-manifold meshes, and Sketchup does not have the ability to export manifold meshes, so I'm afraid this conversion process is only one way. You can really only export from TopMod and import into Sketchup, but not the other way around. All of the meshes that TopMod generates are manifold , aka watertight. This means that there are no holes in the mesh. Here is that definition put another way:

@unknownuser said:

Quote:
A Manifold mesh is a closed polygonal mesh where each vertex is surrounded by a 'fan' of triangles. This means there are no 'OPEN faces' or stray elements like edges or verticies.

So if you were to fill a mesh generated by TopMod with water, no water would be able to escape, because there are no holes, or open faces. However, sketchup is a much more free form design tool, and it allows any kind of geometry, including dangling edges, holes in faces, multiple objects, etc...

The "g mesh" command in the obj file from Sketchup is part of the OBJ specification for the file format, which allows OBJ files to have more than one mesh in them. TopMod only supports obj files with one manifold object in them.

So in short, to get a mesh from Sketchup into TopMod, you will have to go through another more advanced program such as maya, which has some really great tools to convert non-manifold meshes into manifold meshes (fill the holes, fix dangling edges/vertices, etc...), and also to combine separate meshes. So if you have a file with 2 cubes in it in Sketchup, it may seem very simple to just export it as an OBJ file, and import it into TopMod, but you would really need to import that OBJ from Sketchup into Maya, combine the 2 meshes into one object (they still don't have to be touching eachother, but they need to be "combined", in the Polygons -> Combine menu in Maya), and then fix the non-manifold issues with the mesh (there is actually a great tutorial about this concept here: http://www.3dbuzz.com/vbforum/showthread.php?t=157746).

Then you can easily export the mesh from Maya as an OBJ and import it into TopMod. If you don't have access to Maya, there are some open source tools that can do the trick, but they are not as robust as Maya, and it may be more difficult. I suggest trying out Wings3D, it's a wonderful open source 3d modeling tool:

http://www.wings3d.com/

here's a tutorial on fixing manifold issues:
http://www.virtualritz.com/tutorials/us ... -topology/

Let me know if that makes sense. I can try explaining some of this in Spanish for you, but so many of the technical terms don't translate, I've always found it difficult to talk "3d" in Spanish. Anyways, please let me know if you need more help getting something to work, or if you want a mesh converted, send it to my email at dvmorris@gmail.com and I'll convert it in Maya for you and send it back...

Dave
Juan,

TopMod does not have the ability to import non-manifold meshes, and Sketchup does not have the ability to export manifold meshes, so I'm afraid this conversion process is only one way. You can really only export from TopMod and import into Sketchup, but not the other way around. All of the meshes that TopMod generates are manifold , aka watertight. This means that there are no holes in the mesh. Here is that definition put another way:

@unknownuser said:

A Manifold mesh is a closed polygonal mesh where each vertex is surrounded by a 'fan' of triangles. This means there are no 'OPEN faces' or stray elements like edges or verticies.

So if you were to fill a mesh generated by TopMod with water, no water would be able to escape, because there are no holes, or open faces. However, sketchup is a much more free form design tool, and it allows any kind of geometry, including dangling edges, holes in faces, multiple objects, etc...

The "g mesh" command in the obj file from Sketchup is part of the OBJ specification for the file format, which allows OBJ files to have more than one mesh in them. TopMod only supports obj files with one manifold object in them.

So in short, to get a mesh from Sketchup into TopMod, you will have to go through another more advanced program such as maya, which has some really great tools to convert non-manifold meshes into manifold meshes (fill the holes, fix dangling edges/vertices, etc...), and also to combine separate meshes. So if you have a file with 2 cubes in it in Sketchup, it may seem very simple to just export it as an OBJ file, and import it into TopMod, but you would really need to import that OBJ from Sketchup into Maya, combine the 2 meshes into one object (they still don't have to be touching eachother, but they need to be "combined", in the Polygons -> Combine menu in Maya), and then fix the non-manifold issues with the mesh (there is actually a great tutorial about this concept here: http://www.3dbuzz.com/vbforum/showthread.php?t=157746).

Then you can easily export the mesh from Maya as an OBJ and import it into TopMod. If you don't have access to Maya, there are some open source tools that can do the trick, but they are not as robust as Maya, and it may be more difficult. I suggest trying out Wings3D, it's a wonderful open source 3d modeling tool:

http://www.wings3d.com/

here's a tutorial on fixing manifold issues:
http://www.virtualritz.com/tutorials/using-wings3d-to-fix-topology/

Dave