[osg-users] Convert OSGB to Blender Formats

[Thomas Widmer]

Hello,

I hope I can ask my questions here in this forum. If misplaced - sorry. Let me know if and where I can place them, if not here.

I tied to run the osgconv.exe with different parameters on a model I created with MATCH-3DX (see screenshot about data structure) to create a textured OBJ mesh. It doesn't need to be OBJ. It can also be FBX or some other format I can read with Blender. 

Here some of my command lines I used:

osgconv DSM_Mesh.osgb DSM_Mesh.obj

osgconv -O OutputTextureFiles DSM_Mesh.osgb DSM_Mesh.obj

The result is a small blank OBJ file without any geometry and texture. The reason may be the data structure from the OSGB output, which is a LOD OSGB, storing the OSGB result in multiple tiles of different levels.

I used the osgviewer.exe which can read the result perfectly, therefore I hoped I can use it in the same way for the conversion.

I used OpenSceneGraph Library 3.6.5

Best regards,

Thomas

[OpenSceneGraph Users]

Hi Thomas,

I had others might provide some guidance as I don't have any experience with Blender to share. The best I can do is provide general tips.

The OSG file format contains all state and internal nodes of a feature rich scene graph, and the structure of the scene graph can be a deep hierarchy.

The .obj format is a very simple format and can't represent the majority of the OSG's scene graph, so exporting from OSG to OBJ will only work well for very limited scene graphs.

FBX might provide more capabilities, but again it won't represent much of the OSG's scene graph so again there will be limits about what you'll be able to export.

The OSG tends to be used for final graphics applications rather than for data exchange, so the data tends to go from FBX/OBJ etc. to OSG.

Robert.

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[Thomas Widmer]

Thanks Robert!

I tried FBX already, but didn't manage it to get it running. I think the main issue is the levels of details used for OSGB and how I can "access3 them to be used for the conversion. If someone has an idea how to do it, let me know.

At the moment I'm busy with work at my office, but I will try to check it out perhaps the next week.

[OpenSceneGraph Users]

On Wed, 30 Sep 2020 at 16:10, OpenSceneGraph Users <osg-...@lists.openscenegraph.org> wrote:

I tried FBX already, but didn't manage it to get it running. I think the main issue is the levels of details used for OSGB and how I can "access3 them to be used for the conversion. If someone has an idea how to do it, let me know.

At the moment I'm busy with work at my office, but I will try to check it out perhaps the next week.

There is limit to how much you'll be able to export from an OSG scene graph to formats associated with modelling tools that are more focused on individual model components rather than whole worlds.

You may need to pre-process the OSG scene graphs to make them more suitable for export, or export specific subgraphs.

Robert.

 

[Thomas Widmer]

Thanks Robert!

I will try to find out more about pre-processing of OSG. In case you have a good starting point for me, where to find information about it, let me know!

[Andreas Ekstrand]

Hi Thomas,

Unfortunately, the FBX plugin doesn't seem to handle LODs at all. That would be a welcome addition and if I just had the time I would gladly look into it.

The Collada (DAE) plugin supports it however, and you should be able to import DAE into Blender. I know that building the Collada plugin can be a pain though, and if you want a format-agnostic solution I think the most common one is to separate the model into the different LOD components and convert and import them one by one.

You're of course welcome to have a look at our tool Remo 3D, where you can import e.g. OSG formats, apply various edits if necessary and export to Collada or separate FBX, OBJ, etc. per LOD.

Regards,
Andreas

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[Thomas Widmer]

Thanks Andreas!

Yes, I went through DAE and imported each tile individually, which worked. 

In Blender I needed somehow still to move some tiles in X-Axis and Y-Axis to make them fit to each other. MeshLab did this automatically.  

Another option was for me using MeshLab, which surprisingly also took care of the "georeferencing" between the tiles. 

Yes, FXB would be great, as it includes the texture already "inside" - but at least I was able to get it somehow loaded.

As mentioned, work keeps me a little bit busy, so I will try out Remo in the future.