Advice on how to do solve a project needed [thanks in adv]

Hi forum.
I am trying to solve a project. I might be a little bit burn from the week, but I can not exactly figure it out how to solve it.

I have the coordinates of two points on earth. I need to find the line that connects those two points on the planet. The line will be extended till it find itself again. Meaning I will get a section of the earth defined by an elipse that touches those two points. The challenge comes here:

I need to find which countries the line crosses. So far I think I know how to get the line that crosses two points on a sphere. So I am guessing this is not a “model” task, but a mapping one and finding the countries through a texture of the planet applied to the sphere in rhino.

What It could be easier is to have a 3d precise earth model in Rhino an avoid texturing. I found bunch of them made with polys, but I guess to find intersections and angles on Modo (in my case) will be a hassle.

If anybody has a tip or a idea of how to do this or where can i find a precise model of the earth in 3DM that might help.

Thanks a lot for your time.


Here a part of the solution, it uses @it to read a shpaefile of earth

Earth shapefile borders are on internet

The borders of earth are put on a sphere with a given radius.
I also use Custom Preview from Human to get a textured earth.
Image from

I trace a Geodesic between the 2 points and search intersection. To have all the intersections change Rhino tolerances to 10 to intersect geodesic and borders (polyline).

Country code here in English (22.3 KB)

If you want to prolonge the “line” which is an arc on a spheric earth it will give you a circle and not an ellipse !!!

The version that cuts the planet !! (21.0 KB)

1 Like

Thanks a lot , its great to have this community. Unfortunately…the client…is lost…:frowning: