Delete everything inside model / create a Hull


I’m trying to reduce a complex model for later use in Unity and wanted to ask if anyone knows a way to select all objects inside a model to later delete them ?
I basically need the hull of the model. My first approach is a script that uses the selVisible function from different view positions and then inverts the selection to get only the faces inside, but that doesn’t work in all cases. Especially if faces are overlapping.
I would really appreciate it, if someone could help me cause this would save a lot of work. Thanks !

Are you looking to separate the inner and outer faces of a shell?


Thanks for the quick response.

Im searching for a way to clear everythin inside a model. “Undoing” the shell or flatten the outer hull surface again is part of that. I want to save as much geometry as possible that is not visible from outside. Practicly genereate a hull of an object.

Hello - I think this is probably not the full answer for you, or maybe not at all but it might help, so I’ll run it by you- this plug-in adds the command ExtractTangentFaces (you’ll need V5, SR9 to run it). I made it for cases where there is a thinwall shell (joined polysurface) and you need to isolate the surfaces on the outside from the ones on the inside, as for rendering. Anyway. it might be worth a try- save and then drag and drop the rhp file onto an open Rhino (or double-click) to load it up the first time.

ExtractTangentFaces.rhp (39.5 KB)

Note the tangent angle tolerance is user defined - it defaults to one degree but you can set it to anything you like. The larger the number of course, the less tangent the ajacent surffaces need to be in order to be included- the face selection is recalculated to the new tangent tolerance if you change it at the command line.

@Micha, I don’t know if this thing may be of any use to you, for rendering complex objects.


Thank you, I will keep it in my mind for a situation like this.


Where an imported model has everything on one layer or an untidy jumble of layers, one way to extract objects is to create one or more layers for the items you want to keep, turn these layers off and start moving objects to those layers.

If you also create a head layer for all of the existing layers, then you can toggle the visibility between the two layer groups and quickly get things under control.

Similarly you could select items to keep and ‘export selected’ to another file then copy and paste further items into the new file

Hello Pascal,
I managed to install the SR version of Rhino and tryed out your plugin. As I can say it works pretty fine to select the tangent faces of one face according to the angle but would it be possible to select multiple faces to start from and then insert an angle ? When I add other faces to the selection and change the angle it selects the tanget faces only in relation to the first selected face and not to the faces that have been added to the selection later on.

Thanks very much for that plugin !

It is probably possible to have multiple seed faces - as it is, you run the thing multiple times for the same effect, is that correct, getting X number of polysurfaces as a result?

What I am not sure of is handling colliding selections from different starting faces- it might be simple enough but I can see that is one thing that needs to be handled.