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I have extracted a 3d satellite image of a city to a .rdc file using renderdoc and imported it into Blender then selected ALL and joined to a single mesh (ctrl J). I have 'cleaned' it up in edit mode using the lasso tool and then delete vertices. There are still many small objects which are 'floating in space' (not attached to the main object (see image below with one such selected with the lasso). Is it possible to select ONLY those small objects for deletion? I have manually removed many but there are still some which I cannot 'isolate' and 'lasso' as they are too close to the main object to be able to select with the lasso without also selecting part of the main objectenter image description heren object. Maybe this could be done BEFORE joining all meshes?

The following are the object view and edit view of the (3d satellite image) model enter image description here

enter image description here

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    $\begingroup$ why don't you just select one vertex of the main object, press ctrl-L and hide them? then you can remove the small ones. Or if you wanna delete all of them, after press ctrl-L you can press ctrl-I (i am not sure whether it's ctrl-i because i am working on a mac, but i mean invert selection [1]: i.sstatic.net/vR633.png) and delete them $\endgroup$
    – Chris
    Commented Jul 10, 2023 at 5:03
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    $\begingroup$ does hovering over the object and pressing L to select it not work? $\endgroup$
    – Harry McKenzie ♦
    Commented Jul 10, 2023 at 5:48
  • $\begingroup$ yes, i think that works too $\endgroup$
    – Chris
    Commented Jul 10, 2023 at 6:45
  • $\begingroup$ Thanks for those suggestions. However They do not seem to work. I selected one vertex but I only know how to hide using the 'scene collection' panel and there is only one mesh displayed and so hiding it hides everything. Is there another 'hide' function? And hovering over one and pressing L only selects a few virtices unless it is a simple mesh eg a triangle. Also that requires finding all the 'floating' meshes. $\endgroup$
    – John Arnold
    Commented Jul 10, 2023 at 7:17
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    $\begingroup$ If you go to FACE select mode before pressing L it will only select polygons, stray vertices and edges won't be selected. So the workflow is Select object > TAB into edit mode, 3 to go to face select, press L while hovering over a face, 1 to go to vertex select mode, CTRL + i to invert selection, X to delete > vertices $\endgroup$
    – Gorgious
    Commented Jul 10, 2023 at 9:55

1 Answer 1

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If you know you have only one big main object and a lot of floating ones, you can separate by loose parts.

  • select your main object and go into edit mode
  • select all geometry
  • right-click and Separate > By Loose Parts
  • go back to object mode
  • select your main object, invert selection and delete
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    $\begingroup$ Since he wants to delete all smaller parts, why bother to separate them all into single objects and have a hell of a lot new objects there (if there are many)? Just select the main mesh in Edit Mode, invert selection and delete the other parts. $\endgroup$
    – Gordon Brinkmann
    Commented Jul 10, 2023 at 6:40
  • $\begingroup$ Oh right, way simpler! $\endgroup$
    – taiyo
    Commented Jul 10, 2023 at 6:49
  • $\begingroup$ Hi Gordon. Is your method going to work with a single mesh? If so what is the keyboard command to Invert? Also if I only have one mesh how do I select a particular object? Thanks taiyo I am at present in the middle or using your method however with a huge number of vertices, faces (over300,000) etc it has been now running for over 10 minutes and not completed yet. $\endgroup$
    – John Arnold
    Commented Jul 10, 2023 at 7:29
  • $\begingroup$ Wow, this should really not take so long. Sure, depends on the machine but for example i have 3 million faces and 300 floating objects joined/separated in 1-2 seconds. Invert shortcut is Ctrl+I (Cmd+I) or you do Select > Invert in the header menu (top left). $\endgroup$
    – taiyo
    Commented Jul 10, 2023 at 8:37
  • $\begingroup$ My PC config contains an i7 9700K cpu and 8Gb ram (only). I tried your method on a very simple blender project consisting 3 separate meshes combined into one (ctrl j) and it separated them instantly. Then tried on a more simple but still complex 3d satellite image and after a couple of minutes of not finishing I killed the process. Regarding using Invert I don't know how to select "the main mesh" in edit mode. I will add an image of the model above Blender file far too large to upload. $\endgroup$
    – John Arnold
    Commented Jul 10, 2023 at 8:49

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