Let’s say I select a polygon on a map, like the GeoPolygonField, how do I call this information in my grasshopper model?
I’d say I should use Get Geometry, but I’m loss as to how to do this in Viktor.

The GeoPolygonField returns a GeoPolygon which in turn consists of a List of GeoPoints. Any GeoPoint contains its coordinates in either latitude/longitude (, geopoint.lon) or in rd coordinate systems.

So if you drill down deep enough, the GeoPolygon is just a list of coordinate points. That basic data can be used in your case to input it in your Grasshopper model.
How to actually use that data is kind of up to you and how you build your Grasshopper script. As you can see in our GH tutorial a script is used which takes in three inputs using Hops. You could obviously do something similar to use the data in the GeoPolygon in your own GH model but again, that’s up to you.

Let me know if that clears some stuff up!