View Full Version : DWG Files - problem polys

08-03-2007, 07:23 AM
Hi - Not sure if this is the appropriate forum to ask but

I was agiven a dwg file from auotcad which I've translated through google sketchup and exported as an obj. so far so good but alot of the faces look black and dont appear to have a normal/polygon associated with them.

on closer inspection I can see a normal running parallel to the poly face on some of them, on others its skewed at a really acute angle - any ideas why this is and is there anything I can do to repair this en mass as there are a lot of polys



08-03-2007, 07:28 AM
Okay answered my own question - just triangulate the whole lot

08-03-2007, 08:51 AM
"Black polygon" usually happens when polygon normal vector is wrong calculated. It's good to know how it's calculated- from first, second and the last point. So, if they're in the same location (multiple points in same place, or one point added to polygon's point list multiple times by mistake of importing/exporting program/plugin) "black poly" is appearing in that place.. Weld Points or Merge Points might help getting ride of them..

"Black polygon" can be also made by mistake in Modeler while using 'p' tool for filling gaps in geometry - when you selected multiple, unwelded points, and thought it's one point..