[Solved] So! I have a file where my meshes are subdividing on import... somehow.

[FurryWrecker911]

SOLVED: Solutions in replies 4 and 5.

I have a file a coworker was working on who was having some baking issues. On investigation I noticed a lot of polygons were splitting at hard edges and subdividing themselves to round out. After spending 3 hours here fussing with it inside and outside of Substance I've concluded it's purely a fault with this .sbs file. Importing the .fbx files (the low, cage, and high are all affected by this) into a new .sbs, or even into an .spp shows no "airbagging" as I come to call it and bypasses the issue, but that's not why I'm here. I want to know what could cause this.

[Nicolas Wirrmann]

Do you have n-gones in your model?
Also what shader are you using on the 3d view?

[michael_11]

this looks like an issue with smoothing groups

ind 3dsMax, if there are no smoothing groups applied, the mesh is displayed, as if each face was a separate smoothing group. However, if you import such a mesh into other tools, they display those faces without smoothing groups assigned in a different way (this might be what you call airbagging)

so I would check the smoothing groups (in May it would be soft/hard edge normals) as a first step

[FurryWrecker911]

Do you have n-gones in your model?
Also what shader are you using on the 3d view?

No Ngons. I made sure to clean them all up using Modo's stat viewer.
I'm using the OpenGL shader. It's all I got. Iray is broken, but that's an issue to solve another day.

this looks like an issue with smoothing groups [...] I would check the smoothing groups (in May(a) it would be soft/hard edge normals) as a first step

There's no smoothing groups applied. Hard Edges and Vertex Normals are applied though. For kicks I did try to add a smoothing group to the whole model and it changed nothing. Soft edges still airbag, and like I said it's only in this .sbs. If I were to import it into a new one from scratch, exact same model, it doesn't airbag.

[Nicolas Wirrmann]

Are you using the tesselation shader? if so set the height scale to 0 in the shader parameters.

[FurryWrecker911]

Are you using the tesselation shader? if so set the height scale to 0 in the shader parameters.

Well I'll be darned. That did it. Thanks, mate!

I also saw by default in new files the material is usually set on:
3D View> Materials> Default> Definitions> Physically Metallic Roughness [Default]> Parallax Occlusion
instead of tesselation. I knew there were shader params somewhere but didn't know where to start. Solved.