I downloaded the trial version of Sketchup and searched in the 3D Warehouse for free skatchup models of furniture, that could actually be purchased. I opened the downloaded files with Skatchup, clicked on the lense to search for monochrome, to display the models without textures, and reverse faced all the iserted faces (the dark surfaces, as these dark surfaces are otherwise displayed invisibly in Dialux evo. I then exported the SKP files as 3DS and tested these in Dialux.

I decorated and lit the apartment and all renderings worked fine, but now I'm getting errors in ray tracing, that I never had before with the same 3D models and the same lighting and lamp positions.

What could be the problem ? Some of the triangles (3ds models are made up entirely of triangles) that were previously light suddenly become dark.

As you can see from the screenshots everything woked fine before.

Now i getting these dark triangles and some parts of the 3d Models are getting invisible, that wasn´t invidible in the Raytracing before.

As you can see the same Painting is getting dark triangles now and did not change the luminar position or 3d Model.

I would be pleased, if someone can help me with my problem.

Even if the the room is not rendered, it now show up some dark survaces on the Picture, that wasnt dark before.

You can now see them on the towels and the Toilet.