We maintain a map of the 3D areas in Google Earth. This is achieved with the help of GEB readers who send in KML outlines of new areas. However, we often receive outlines that are not ideal and need some manipulation before inserting into our KML file. We have created a number of scripts that help us combine various combinations of Polygons and Paths to deal with most situations. But, there are still some cases where manual intervention is required. Possibly the most tedious task is when a Polygon or Path needs to be split into two. In Google Earth, this requires duplicating the feature with copy/paste, and then deleting half the points in each copy. For features with a large number or points this can take a while.
So, we decided to make a simple tool that splits Polygons or Paths.
For best results, just save from Google Earth a single Polygon or Path that you wish to split as a KML file then upload it below. It should show the feature on the map. If there is more than one feature in the KML then click on its name in the left hand column. It should then highlight the vertices. If it is a Polygon, click on a vertex to split it at that point and convert it into a path. Click any point on a Path to split it into two Paths. Click ‘Save’ to download the result as a KML file.
If you submit KMLs of new 3D areas, please follow the guidelines found here. Essentially, the ideal format is a single Polygon for independent new areas, Paths for extensions, only covering the new areas and only on the outer edge.
[ Update: 2017-02-04 Updated the code to also handle MultiGeometries. ]