Edge Outline

Sometimes, Edge/Silhouette Outlines bring you unexpected results.
I guess it's got something to do with angle and polygon size.
I found out that you can hide the undesirable outlines with a copy of the troubled objects (I'm not sure whether this works for every situation or not.).

In version 2.7.5 days, I heard that you must avoid a duped object with same position and scale with the original. But, it seems OK now.


How it works
From the corner, should-be-hidden line is rendered. Dupulicate the object. Then, turn off the Edge Outline feature for the duped copy. It hid the undesirable line. It's very important. It seems that copied object can hide the original's faces, but it won't work the reverse way.

Still better...
Here's the better way. Before the duplication, set up material, render without edge outlines.

Then, make a copy of the object. Crank up the luminance to 100% white, and turn off the specular value for the copied object. Turn off all lights and render.


Composite two images. Place the outline image over the textured one. Use Multiply mode for the top layer.

Since you got Outline layer, you can change its opacity or even apply some filter.


Other troubles
It has no outlines for the rounded area.

In this case, solved by re-imported with smooth shade angle setting to 50.


Non-welded edges(?) cause undesirable outlines. You can import those objects with Merge Polygons option.