How do I get a MeshRegion from an obj file, or from Geometry3D

Question

How do I read in an obj file as a MeshRegion so I can e.g. compute its area?

If I just import the object and try Area[O] it tells me it is not a correctly specified region, even for e.g. the StanfordBunny.

Also, how do I turn Geometry3D into a MeshRegion? For example

Area[ExampleData[{"Geometry3D", "SpaceShuttle"}]]

does not work either.

It seems that geometry has more than one representation in different parts of Mathematica - bad.

Answer 1

Well, you have to first convert it to a MeshRegion. Let's take the space shuttle for example:

shuttle = ExampleData[{"Geometry3D", "SpaceShuttle"}]

Now, we discretize it, since it's a Graphics3D object, we use DiscretizeGraphics:

ds = DiscretizeGraphics[shuttle]

Now, we can find the Area easily:

Area[ds]

177.301907

Similarly for the horse:

horse = ExampleData[{"Geometry3D", "Horse"}]

dh = DiscretizeGraphics[horse]

We compute the surface area:

Area[dh]

0.0358690432