I'm a beginner in Blender - i have a problem with mysterious shades in flat surface. Model comes from SketchUp (exported to OBJ / imported to Blender).

Model is composed of blocks, shades are near block's edges (but only on some of them). My idea was Sketchup model have some smooth edges, but it haven't...

Any idea what is the problem??

Thank you very much in advance!

EDIT full resolution preview: http://lukex.name/temp/preview.png

• remove doubles and recalculate the normals – Chebhou Jul 9 '15 at 20:53
• If you look at the topology in those places I'm guessing they are caused by long tris and ngons. See if flat shading (3D view > Tool Shelf (T) > Tools > Shading) and recalculating the normals helps (Ctrl+N in Edit mode). – gandalf3 Jul 9 '15 at 20:57
• I had the same problem. All the objects look as if their faces were set to smooth. I solved the problem by setting flat AND giving a look to "Autosmooth" "checkbox in Normal" panel under "Object data" tab (I had to un-ceck them all). By seeing your screenshots only I would say that you may suffer of the same problem...give it a try – Carlo Jul 14 '15 at 21:10
• SketchUp exports horrible geometry to .obj. I didn't ever come across one that I haven't had to fix. Normals and doubles are usually the most common, thats very true. – Jaroslav Jerryno Novotny Aug 14 '15 at 15:30

In Blender OBJ import options unchecking Smooth Groups and no Split by helped (in case of shadows on simple blocks //Groups in SketchUp had one surface identical and Smooth Groups in blender causes this problems).