MIGRATING FROM ArcGIS TO GOOGLE EARTH: CHALLENGES AND OPPORTUNITIES FOR MAKERS OF GEOLOGICAL MAPS

For the past decade, ArcGIS has been the preferred platform for digital mapmaking in the geosciences. During that time it has evolved into a sophisticated data management and desktop map publishing tool. However, it started as a command-line-driven, geography-oriented, high-end program for graphics workstations, and to this day retains its steep learning curve. Most students (and professionals) need a full semester course in the technical details of ArcGIS before they can begin to concentrate on geoscience applications. In contrast, Google Earth (at least after the name change from the original Keyhole product) is a popular, easy to use program intended for the non-technically-oriented majority and with the aid of Keyhole Markup Language (KML) it has gradually developed into a potentially serious platform for geoscience map making. Unlike ArcGIS, Google Earth is cross platform, which is increasing important as Mac OSX and Linux erode the dominance of the Windows operating system, especially among academics. However, migrating map databases from ArcGIS to Google Earth requires significant work, and the problem is not entirely solved by off-the-shelf software such as the 'Arc2Earth' application. For example, ArcGIS strike and dip symbols cannot be simply exported to Google Earth placemark icons, because the latter do not retain a fixed spatial orientation. Also, differences between true north and grid north cause alignment problems on larger maps. Nevertheless, the rewards of the migration effort are significant in terms of enhanced visualization and availability to a mass audience. Examples from our recent fieldwork in western Ireland illustrate the increased level of sophistication achievable when ArcGIS databases are exported to a combination of Google Earth ground overlays and Collada 3D models. We have designed block diagrams that novices can easily position on the Google Earth terrain without coding and which can be made to change position and appearance as a function of time.