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Selection seems to work in wierd ways. I have a 3D File with ~4.000.000 Tris and ~120.000 Objects. The file results from a CAD software and needs to be further processed.

My idea was splitting the File in smaller parts because opening it takes minutes and the viewport is very laggy. But the real problem is that simple things like selecting parts of something take ages (for larger areas minues) and give not the expected results. (100% one CPU-core the others idling - The machine isn't the problem)

Has someone tips for working with files like this? enter image description here

Edit: Selectable parts seem to be consitend till i moving the selectet parts to a different layer (takes minutes to finish). After that other parts become selectable.

J.Doe
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3 Answers3

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Here are a couple of things, you might want to try (actually, this is more of a comment than an answer, but I haven't earned privilege to make comments yet).

  • Selections in outliner (the right hand side panel) are much faster than in the 3d area.
  • You can try hiding other objects with Shift+H (Alt+H to clear).
  • Alt+B will allow you to select a small portion (box select) to work in edit mode. You can switch back to the normal mode by pressing Alt+B again.
Ray Mairlot
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Blender Dadaist
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  • Thank you for the tips. The outliner is totaly useless in my case because all the more thand hundred thousends objects are named like: "Mesh123456 Group123456 Model" with rising numbers. And i havend yet figured out if there is some structure i could use scripting. Hiding brings close to no performance increas. The viewport rendering isnt a limiting factor. Alt-B is a cool thing i never saw bevor... but sadly dosent help with selecting things. – J.Doe Sep 05 '18 at 14:28
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I probably found an answer why everythin is so slow with so many objects. The specific answer applyes to scripting... so i guess the UI actions use the same functions.

"Most operators cause implicit scene updates. It means that every object in the scene is checked and updated if necessary."

https://blender.stackexchange.com/a/7360/47253

J.Doe
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Try to use the same object, for example, if you gonna use the same object a big amount of times, you could simple instead of duplicated, use duplicate linked, since this will duplicate the main object but without creating a new instance of it, i mean everytime you duplicate a object, you create a new instance of it, which consumes more memory, if you use duplicate linked, you will have the same result as duplicate, plus you'll save more resources

Alan Parson
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  • Thes are CAD files and i cant change the way they are created. – J.Doe Sep 05 '18 at 17:41
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    Had you tried to move the objects to a separated layer? sometimes this can help improve speed, all those solutions are what i used to do, cause i had the same problem sometimes, mostly cause a lot of polygons and tris in the same place, so, this could help you, another try is to try to join objects into one bigger, only you have to do is uv map separately and create separated materials for each one (for customized texturing) then control + j and you'll have 1 object with 6 diferent textures – Alan Parson Sep 05 '18 at 18:12
  • I have a hard time moving them to layers because I can't select them properly. But I tried this extensively and it got me no noticeable performance increase. The viewport rendering of 4 million Tris shouldn't be the problem on this Mashing (i subdivided a cube to 16 million and it was running nicely). But 32k copies of a cube object got me in to performance trouble again. – J.Doe Sep 05 '18 at 19:50
  • You are totally right - joining the meshes to nicely structured objects helps a great deal. But again I have more than 100k of them and can't box select them properly (luckily selecting by Material works fine). Also, joining ~6k objects into one causes the mashing to hang roughly 15 minutes before completing. – J.Doe Sep 05 '18 at 19:50
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    huh, i'm so sorry i can no be useful to you, it looks like mostly the problem is about how blender manages itself a bunch of objects, perhaps workstation specs?, i have 64gb ram + 2 1080, plus i7 and still it hangs for me, perhaps you could see around how to optimize blender to use all your cores, try switching from gpu to cpu, i wish you good luck with it, i hope you could find a useful solution, if you achieve it, please let us know here – Alan Parson Sep 05 '18 at 22:31