Thanks for doing this. That said, not sure I understand. The first question is: From what frame of reference? Inside the part or outside? And then, of course, there's the fact that the long edges are straight, which means they are not concave/convex, regardless of where we look at them from.
Just trying to understand. I am just starting to look at the internals of slicers. At first pass I thought that the seam point selection might have been influenced by infill kind or infill segment end points as they join the inner wall. That was easily debunked by simply eliminating the infill, which changed nothing.
Herea's the most important question though:
How do I know which approach will produce good parts?
I am printing very large parts. Some of them will take upwards of 50 hours print time. I need a way to know the slicer will not introduce these kinds of errors. This seam location issue produces horrible defects across hundreds of layers. Out of the roughly 900 layers of the part that triggered this investigation there might be 100 without visible zits due to seam issues. My only option right now is to use Simplify3D until I can trust Cura to deliver defect-free files. As I said before, I really want to use Cura (even though I own an S3D license), but I can't afford to waste a part to see if the slicer made a mistake.
Again, I'd appreciate any and all advise on this front. Thanks.