Importing data from Global Mapper

I am really new to global mapper. Just wondering how do you get terrains from global mapper inside Rhino?

I have the site boundary which I traced out in Google earth, exported the kmz file and imported it in global mapper to locate my site of whose terrain I wanted to export.

The trouble is , when I export the fbx file and import it into rhino, I lose my site boundary.

What is the best method to bring a terrain inside Rhino from Global mapper?

Here is my kmz file.

I tried to export the contours, but they are innacurate and are overlapping within Global mapper. Hence attempting to directly export a terrain model from global mapper itself.