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I use blender to render patent images, which require "black and white" drawings. Hemi is very handy because 1 hemi lamp is enough and no shadows. But this time I got this: enter image description here After using gimp Edge detect -> Revert colors -> Auto-crop image -> Threshold to 239 -> 1 bit color index, I got this: enter image description here It's still usable, but it's ugly! So what happened? Hemi lamp used to be simple and works great! All I need is to put 1 single hemi lamp at origin (0,0,0)!

After I set 0.01 thickness(using extrude/z/.01) to those "black planes", they're all dark/black now... enter image description here

It seems to have something to do with camera direction. There would be no dark/black planes if you looked from downside of the planes, just like this: enter image description here

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There is no edges showing on the planes because they have no thickness. Add a slight thickness to each plane and you should see detectable edges.

This seems an odd way of doing this though, I'd look into blender's edge detection functionality or freestyle as an alternative.

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  • $\begingroup$ Yep, sounds like a highly inefficient and inaccurate way of doing this, even a viewport capture might be faster. $\endgroup$ – Duarte Farrajota Ramos Apr 18 '17 at 16:51
  • $\begingroup$ Sure. I had tried them both. Blender's Edge Detect can only detect some of all edges —— even 80% would be confused. Freestyle is the opposite —— sometimes it renders more edges than needed. I was using Freestyle all along and forgot to mentioned it. Those steps are merely to remove colors and keep only the edge lines. $\endgroup$ – jon doe Apr 19 '17 at 7:25
  • $\begingroup$ It didn't work... I post the result in the original post because I can not post pictures here in the comment. $\endgroup$ – jon doe Apr 19 '17 at 8:46
  • $\begingroup$ @jondoe interesting, I'll take a more detailed look when I get a chance. I still think that this should be doable with just freestyle. $\endgroup$ – Sazerac Apr 20 '17 at 3:18
  • $\begingroup$ It seems to have something to do with camera direction. There would be no dark/black planes if you looked from downside of the planes. Any ideas? $\endgroup$ – jon doe Apr 20 '17 at 3:41

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