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i work as an 3d artist with 3DS Max; and i thought to give Blender a try.

My problem started that Blender doesn't seem to have native import for IGS/IGES or other CAD files. I solved that by importing the object into 3DS Max and converting it into a OBJ file. (No big deal)

Trying to open the obj file is very slow and sometimes it seems Blender just gave up; but in the end it opens. File size is 1.53Gb and the model has around 15.858.388 triangles. As you can see the models i work with are quiet heavy.

But know i got my main problem; that's where my question is... When i try to work with the model; even isolating an object; Blender sometimes freezes for a few seconds.

Am i doing something wrong? Do i need to enable or disable some settings? Can it be the obj file i exported?

Because everything works fine with 3DS Max; and i want to have the same experience with Blender.

I use the same PC for both programms, so i don't think it's the problem. Intel Xeon v4 @ 2.20GHz NVIDIA GeForce GTX 1070 Ti (MSI) 32GB RAM

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    $\begingroup$ 15,858,388 is a quite large number for polygon model, Blender are not good at dealing with that much of data in one operation(due to the core structure performance). $\endgroup$
    – HikariTW
    Jul 18, 2019 at 8:31
  • $\begingroup$ The viewport is slow and even after the implementation of eevee, the viewport is still slow for millions of polygons. Unfortunately, we have to deal with that limitation so I don't think that you are doing something wrong. I guess that max got some kind of level of detail-optimization for its viewport and in fact that's a missing feature of blender since the beginning. However, when it comes to modeling or look development there are a few advantages (IMO) so giving blender a whirl is definitely worth it for archvis or whatever you do. See: blender.stackexchange.com/a/116521/31447 $\endgroup$
    – brockmann
    Jul 18, 2019 at 10:37
  • $\begingroup$ "Blender sometimes freezes for a few seconds" Sounds like a totally reasonable thing to happen on a 1.5Gb model $\endgroup$ Jul 18, 2019 at 11:07

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I've just noticed that 3DS Max has an option to export OBJ file optimized for Blender. That seems to be the solution apart from lowering the polycount on import from IGS file.

EDIT
After some tests i’ve got the following results:
Default import option: 15.858.388 triangles
Optimized import option: 557.088 triangles

Export to OBJ for Blender:
Default import + default export: 1.53Gb file (that’s a killer for Blender)
Optimized import + optimized export: 58.9 Mb

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  • $\begingroup$ The importer is written in python: <blender>/scripts/addons/io_scene_obj/import_obj.py, which theoretically isn't bad thing but it is slow as hell (no multithreading). However, there are some efforts making a C-module out of it as part of google's summer of code which hopefully will be part of blender in the next weeks - .ply seems to be done already. $\endgroup$
    – brockmann
    Jul 18, 2019 at 10:02
  • $\begingroup$ Did you manage to keep the materials while exporting from 3DS max ? $\endgroup$
    – Gorgious
    Apr 22, 2020 at 9:10
  • $\begingroup$ @Gorgious all the models i work with have procedural textures, so i really didn't test that. Sorry for not being of more help. $\endgroup$
    – Benjamin
    Apr 23, 2020 at 10:11
  • $\begingroup$ No problem, you made me discover the blender optimization thing. The method I use currently is to save as a .3ds file and use this add-on to import. It kinda works for simple materials, but I can't manage to import materials with textures. Cheers $\endgroup$
    – Gorgious
    Apr 23, 2020 at 10:15

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