21 Replies Latest reply on Sep 28, 2014 8:53 PM by Jamil Snead

    Making a globe (convex hull)

    Valentine Kunin

      I want to 3d print a globe with continents actually being a little bit extruded from globe's surface, so that you could actually feel them with your fingers. I can find coordinates of the continents' boundaries online; I am thinking about doing the following then:

       

      0) Create a unit ball A (the globe itself)

       

      For each continent:

      1)Transform coordinates of its boundary from spherical coordinates (longitude, latitude, r=1) to x,y,z, getting a bunch of points on a surface of a unit ball

      2)Create a convex hull of all those points and the origin, getting some kind of pyramid, with a vertex at the origin and with a base in a shape of, say, Australia:) 

      3)Scale this pyramid about origin by a factor of, say, 2 (doesn't actually matter if it's large enough); let's call this new large pyramid B

      4)Create a ball C of a radius slightly greater than 1 (say, 1.01), also centered at the origin

      5)Take (A union B) intersect C

       

      Australia is now extruded from the surface by 1% of the globe's radius. Repeat for the next continent:)

       

      I'm a little new to Solidworks, maybe there's a better way to do this? If you think it's all right, how do I do 2)? I found no info on how to create a solid convex hull of a set of points.