Per block OBJ export causes wrong textures

[EarnestWorthing]

Dear community,

For my project I need to export each block individually to OBJ files. As a scene I use 'Generate an Imaginary City'. When I import the objects individually and import the OBJ file in blender I get dark textures which will also appear dark when rendering with blender.

This is not the case when I export the scene as a single OBJ. Here everything works perfectly fine.

Could you please help me further?

The following screenshot of a blender scene depicts the problem:
Dark building: OBJ export (Export models > OBJ > File Granularity: One file per start shape)
Lighted buildings: OBJ export (Export models > OBJ > File Granularity: One file as long as Memory Budget is not exceeded)

Further export settings:

Normals appear correct (blue: outside, red: inside):

Thank you very much for your help in advance.

[EarnestWorthing · Accepted solution]

Cause of the reported issue: transmission value of texture is set to 1 for individually exported objects
Quick fix: set value to 0

It might be helpful for users to have same values for both export versions.

[SimonHaegler]

Thanks for reporting this!

Just to be sure I understand correctly: you manually fixed the Tr (or Tf?) value in the mtl files? Or did you set opacity in CGA?

Would you posting a diff of a "good" and "bad" mtl for your use case?

Best,
Simon