multitextured OBJ seems to shine strongly

Hello everyone,

I use vtkOBJImporter for multitextured OBJ files.

vtkOBJImporter importer = new vtkOBJImporter();
importer.SetFileName(file);
importer.SetFileNameMTL(fileMTL);
importer.SetTexturePath(texPath);
importer.Update();
		
vtkActorCollection actors = new vtkActorCollection();
actors = importer.GetRenderer().GetActors(); 
actors.InitTraversal();

for (int a = 0; a < actors.GetNumberOfItems(); ++a) {
	vtkActor  actor = actors.GetNextActor();
	actor.GetProperty().LightingOn();
	    
	 if (actor.GetTexture()!=null) {
	     actor.GetTexture().InterpolateOff();
     }
	...
 // add actor to view
}	    


In the visualization, these are provided with a strong “shadow”, at least at first glance it looks like this. However, when it is rotated, it seems to be more of an extreme shine.



What went wrong here or what do I have to change so that I can display the data in the usual representation, i.e. completely textured and without shadows?

Best regards

The problem described above mainly occurs with the 3D scanner ‘Vectra’ from ‘Canfield’.
Multitextured objects are a problem. Single textured objects are displayed correctly and get an all-encompassing / complete illumination.

It would be quite helpful if someone could try this out with the attached test data set.
Many thanks in advance.