Exported OBJ/MTL files do not include emissive lighting parameters #45766

New Issue

John Gilbert · 2015-08-12T07:06:22+02:00

John Gilbert commented

2015-08-12 07:06:22 +02:00

System Information
Operating system and graphics card
MacBook Pro - NVIDIA GeForce GT 330M

Blender Version
Broken: tested not working - 2.73, 2.74, 2.75
Worked: (optional)

Short description of error
Exported OBJ/MTL files do not include emissive lighting parameters. MTL file includes Ka, Kd, and Ks, but not Ke data.

Exact steps for others to reproduce the error
File->Export->Wavefront (.obj)
save as test.obj
Look at resulting test.mtl file.

Based on a (as simple as possible) attached .blend file with minimum amount of steps
NA

**System Information** Operating system and graphics card MacBook Pro - NVIDIA GeForce GT 330M **Blender Version** Broken: tested not working - 2.73, 2.74, 2.75 Worked: (optional) **Short description of error** Exported OBJ/MTL files do not include emissive lighting parameters. MTL file includes Ka, Kd, and Ks, but not Ke data. **Exact steps for others to reproduce the error** File->Export->Wavefront (.obj) save as test.obj Look at resulting test.mtl file. Based on a (as simple as possible) attached .blend file with minimum amount of steps NA

John Gilbert commented

2015-08-12 07:06:22 +02:00

Changed status to: 'Open'

John Gilbert commented

2015-08-12 07:06:22 +02:00

Added subscriber: @John_G

Bastien Montagne commented

2015-08-12 10:58:40 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2015-08-12 10:58:40 +02:00

Changed status from 'Open' to: 'Archived'

Bastien Montagne closed this issue

2015-08-12 10:58:40 +02:00

Bastien Montagne self-assigned this 2015-08-12 10:58:40 +02:00

Bastien Montagne commented

2015-08-12 10:58:40 +02:00

Thanks for the report, but never saw any 'ke' in .mtl files - and it’s mentioned not in specifications (http:*paulbourke.net/dataformats/mtl/, https:*en.wikipedia.org/wiki/Wavefront_.obj_file). Would not consider adding non-standard stuff like that, unless you can prove for a very wide acceptance of it?

In any case, not a bug. ;)

Thanks for the report, but never saw any 'ke' in .mtl files - and it’s mentioned not in specifications (http:*paulbourke.net/dataformats/mtl/, https:*en.wikipedia.org/wiki/Wavefront_.obj_file). Would not consider adding non-standard stuff like that, unless you can prove for a very wide acceptance of it? In any case, not a bug. ;)

John Gilbert commented

2015-08-13 10:08:00 +02:00

Don't take my word for it - look at line 174 of export_obj.py already in Blender - you will find map_Ke - the keyword to attach a texture to an emissive color. Works the same way as map_Ka, map_Kd, etc. but for emissive light. Only makes sense if there's also a way to change the emissive light color like with Ka, Kd and Ks for other kinds of light.

Also look at http://cgkit.sourceforge.net/doc2/objmaterial.html
I can find hundreds of obj/mtl examples that contain Ke.

Ke has been part of the wavefront obj/mtl file format standard since 1996.

I'm using it for models of terminals and displays - it's really annoying when Blender strips it out. It's preserved in X3D and other formats.

Please consider it a bug in the import/export obj system - it's effecting my work flow.

Don't take my word for it - look at line 174 of export_obj.py already in Blender - you will find map_Ke - the keyword to attach a texture to an emissive color. Works the same way as map_Ka, map_Kd, etc. but for emissive light. Only makes sense if there's also a way to change the emissive light color like with Ka, Kd and Ks for other kinds of light. Also look at http://cgkit.sourceforge.net/doc2/objmaterial.html I can find hundreds of obj/mtl examples that contain Ke. Ke has been part of the wavefront obj/mtl file format standard since 1996. I'm using it for models of terminals and displays - it's really annoying when Blender strips it out. It's preserved in X3D and other formats. Please consider it a bug in the import/export obj system - it's effecting my work flow.

Bastien Montagne commented

2015-08-13 10:55:32 +02:00

Changed status from 'Archived' to: 'Open'

Bastien Montagne reopened this issue

2015-08-13 10:55:32 +02:00

Bastien Montagne commented

2015-08-13 10:55:32 +02:00

Yeah… well, ke/map_ke is definitively not in official specs… But seems to be indeed rather common extension (http://exocortex.com/blog/extending_wavefront_mtl_to_support_pbr e.g. explicitely cite it as extension), and map_ke was added from #32914, so I guess we can as well add ke too (and support map_ke on import, tsst).

Bastien Montagne commented

2015-08-13 11:09:50 +02:00

Also, since we use diffuse color for emission, I’m going to use it when exporting too, and try to do my best at import stage, but there will be some lack of data here, we cannot do anything about it.

blender-admin commented

2015-08-13 12:04:04 +02:00

This issue was referenced by blender/blender-addons@94c9c4ee33

This issue was referenced by blender/blender-addons@94c9c4ee3370d1feb42fc978a1f0d2db07cb9431

Bastien Montagne commented

2015-08-13 12:10:43 +02:00

Please see commit notes for limitations. Also, could not make extensive testing on this, since I have no .obj with ke values here, please either test this or attach here a few testing files.

Bastien Montagne commented

2015-08-13 12:11:01 +02:00

Changed status from 'Open' to: 'Resolved'

Bastien Montagne closed this issue

2015-08-13 12:11:01 +02:00

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Exported OBJ/MTL files do not include emissive lighting parameters #45766