1. What are KML ground overlays?

Google Earth is the google’s geographical browser that is increasingly popular in the research community. Google Earth was developed by Keyhole, Inc., a company acquired by Google in 2004. The product was renamed Google Earth in 2005 and is currently available for use on personal computers running Microsoft Windows 2000 or XP, Mac OS X. Please follow this link to obtain the most recent version of Google Earth. The biggest benefit of Google Earth are its visualisation capabilities that can not be compared to any GIS. The base maps in Google Earth are of excellent quality (borders, places, IKONOS images) and can not be compared to any existing GIS in the world. In addition you can also add maps from an existing GIS or similar software by generating KML files. In geomorphometry, we are especially interested in the generation of ground overlays, i.e. in draping of images of geomorphometric parameters and similar.

More info: KML tutorial and/or Google Earth user guide.

2. How do I convert my raster maps to KML overlays?

Before you can add an ground overlay, your raster map needs to be reprojected to the LatLonWGS84 coordinate system, then exported to JPG or similar format. You can use this ILWIS script to automatically estimate the bounding coordinates and produce a new grid definition that matches the borders of your area. Once you have resampled the map, then export it as JPG and upload it directly via the geomorphometry.org by selecting the button "Add new KML image". These are some examples. If you work with ArcGIS, then you could also obtain the Arc2Eearth plugin and generate KML files directly from GIS layers at a click of button.

In Google Earth you can set-up the transparency of the raster maps by using the button on the left menu. We advise you to use our reference case study to generate examples. This way, you can compare your results with the results of people doing a similar kind of analysis.

... keep up the good work and let us know if you face problems