Blender Shading issues when exporting the model

Vitus

Resource contributor
Good evening!
I'm moving on with my projects and I am at a stage where I'd like to see the models in the sim. But due to the law of I-can-never-have-nice-things, there's issues and I would like to get your input to produce a better result. There's two issues I am having trouble with. 1. some of the geometry isn't shaded smoothly, the triangles shine through. 2. some hard edges bubble up.

Here's an example of what I'm talking about (P3Dv5):


You can notice the triangles at the crankcase and a little bit at the no 3 cylinder as well. And the strut seems to bubble up as if I didn't sharpen the edges around the holes. To compare, here's the same view from within Blender:


What's curious is that some parts of the geometry work just fine, while others fail and I can't work out what the difference is.
 
From memory red is for seams and blue is for sharp? Are those edges you have issues with marked as both?

Just did a quickie test in Blender and looks like a Seam and Sharp will show as a seam.
1589504182006.png

All edges here have seam and sharp. Wonder if there is a way to confirm which edges are set as sharp without removing their seam.
 

Vitus

Resource contributor
I just ran a test. I removed some of the seams to check if that makes a difference: nope - same result. I disabled auto smooth - nope, same result. I recalculated the normals - same result. I checked for overlapping faces, but there aren't any.

It's really puzzling.
 
Your problem, I think on the strut which seems to bubble is due to your geometry: you should increase the precision of the modelisation
To avoid this phenomena you shoud apply a bevel around the perimeter of each hole of the strut in order to permit a good smooth. Each bevel should add edges which stop the smooth as you wanted.
 

Vitus

Resource contributor
The model is a very old project of mine, which was converted from Gmax. The thing is that the same mesh topology worked just fine when exported from Gmax.

While I am a bit reluctant of changing the mesh, I did give it a shot and added some bevels around the holes and on the long edges top and bottom of the top strut :


Result in P3Dv5:


But there's also shading issues with the barrel of the cylinder. I was thinking that it might have something to do with the normal map that was generated by substance painter, but then it would show up with the same artifacts in Blender.
 

dave hoeffgen

Resource contributor
When you have edges that are marked sharp, do you also have an edge split modifier, actually sharpening the edges?
 

dave hoeffgen

Resource contributor
Nope. What does the split modifier do?
It splits edges using an angle threshold and the ones marked sharp.
In Blender an edge in and object that is set to be shaded smooth can't be sharp, so for a sharp edge you need it split.
 

Vitus

Resource contributor
That's interesting. But this will also create additional geometry, so won't the model become much bigger?

I gave it a shot for the two front struts:


That's much, much better - thank you for the tip! Now the question comes how to make those triangles invisible!?
 

dave hoeffgen

Resource contributor
That's interesting. But this will also create additional geometry, so won't the model become much bigger?

I gave it a shot for the two front struts:


That's much, much better - thank you for the tip! Now the question comes how to make those triangles invisible!?
Can you show me how you set up the modifier?
Also is the object shaded smooth?
 

Vitus

Resource contributor
Here's the modifier:
1589915878171.png


I double checked the smoothing, and yes: the part is shaded smooth. It's also set to auto-smooth at 30deg.
 

Vitus

Resource contributor
Aaaaaaah never mind, I found the issue! It turns out it was the normal map that screwed up the strut and created all those triangles. I had that suspicion and disabled it in Blender, exported and started P3Dv5:
1589919146148.png

So it looks like something has been going wrong when the normal map was generated by Substance Painter. I'll check it out.

I am sooooo happy for the tip about the split modifier. It solved a lot of issues for me, thank you very much again!
 
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