Import Igs vs OBJ and :Tools/Edit normals

[wayneheim]

So question. I had an igs file that seemed to be displaying incorrectly and I clicked to try to recalculate the normals and when I do that it breaks the igs appart. But when I recalculate an .obj file it doesn't break the object appart. I thought once the igs was tesslated it was basically the same as the .obj, ie made of of poly's.

[DriesV]

Hi Wayne

IGES as a format is a bit notorious for not coming in as BREP solids, but rather as a bunch of surfaces.
This can also happen when importing IGES models in KeyShot. And even though the imported model may be represented as a single part in the KeyShot Scene Tree, it may very well consist of multiple individual surfaces under the hood. If that is the case, then that will become apparent when using the Geometry Tools on that part (Edit Normals, Split Object Surfaces etc.).

Unfortunately, there is no way in KeyShot to "stitch" these surfaces together.
Given a choice, I would always recommend to use STEP or Parasolid (x_t) over IGES. STEP and Parasolid have much more robust BREP solid handling.

Dries

[wayneheim]

Thansk DriesV.
So once an object is split into surfaces there is no way to "stitch" them back together? So out of curriosity how does the "split object" option work when it gives you the option of controlling and combining surfaces to control how many new objects you will end up with.

Wayne