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I'm working on a Lego project where I build models out of Lego bricks in LDD and then import them into Blender via various hoops - inside Blender I then optimize them before loading them into Unity for a small game.

The problem is that Lego has so much geometry inside a big model, because it consists of many small bricks that all have studs and at least 6 sides.

I'm thinking that there must be some kind of tool that can raycast all around outside the model and then delete/group/select all internal faces. Do any of you know of such a tool or where to find more information on this subject? Even just a more correct term would be helpful for my google ventures :)

Here is an image of my model with some of the sides hidden so you can see all the abundant leftover data

Thank you! <3

Dulcis
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    relevant https://blender.stackexchange.com/questions/18916/how-to-remove-interior-faces-while-keeping-exterior-faces-untouched – rob Oct 03 '18 at 08:39
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    hmmm, I tried creating a Grid fill of boxes and then Joined them altogether. The resultant mesh approximates lots of Lego brick meshes but Selecting Internal Faces did not work and trying to Remove Doubles / Decimate removed to much geometry at least then Select Internal Faces did select internal faces but in a way that further messed up the Mesh. So YMMV – rob Oct 03 '18 at 09:16
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    Could you provide a small sample file? Or at least some detail re geometry in a screenshot. – batFINGER Oct 03 '18 at 11:44
  • @batfinger I couldn't figure out how to attach the blender file, but I put in a screenshot where some of the faces are hidden to show all the abundant data inside. – Dulcis Oct 03 '18 at 12:06
  • @rob thanks - I'm also currently trying the methods in your link :) – Dulcis Oct 03 '18 at 12:07
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    So the "limit selection to visible" was the techinque that has worked the best so far - I rotate all around the models and select with circle select, and then invert selection and delete - but it's not deleting all the inside faces. Maybe they're too close to the outside layer, but it shouldn't be – Dulcis Oct 03 '18 at 12:23
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    if you exported it as an ldraw file, you could use MeshLab (available on Ldraw.org). Meshlab can be used to remove the interior of a brick. – Millard Oct 12 '19 at 02:20

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One trick I used in 3ds max once, was to bake a tiny AO map. Auto uvif you can. Or maybe can vertex color as well.

But basically whatever faces were totally black, I then selected / deleted. Since we're then basically fully hidden from view.

user62077
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