CREATING ADVANCED ELEMENTS FOR INTERACTIVE GEOLOGIC MAPS IN GOOGLE EARTH USING AN HTML-BASED TOOLKIT

Google Earth (GE) has emerged as a powerful tool for building and displaying interactive, virtual 3D geologic maps. Many geoscientists first discovered the power and utility of viewing geologic maps in a virtual 3D environment by draping existing images of geologic maps over GE terrain as ground overlays. Though this approach provides a quick and easy method for 3D display, interactive maps in GE are most effective when built with selectable polygons (for lithologic units), paths (for curvilinear features like faults), and placemarks (for outcrop and other point data). When highlighted, each of these features can display detailed information (metadata) in associated description balloons. However, some vital components of geologic maps, such as legends, orientation symbols, and cross sections are not as easy to incorporate in an interactive GE map, due to the lack of directly accessible menus in GE and/or the necessity of using 3D modeling programs such as Google SketchUp. To overcome these limitations, an HTML-based toolkit was designed to allow users to easily include advanced elements in their GE geologic maps. Google Earth Map Development Tools accessible at http://csmres.jmu.edu/Geollab/Whitmeyer/web/visuals/maptools.html include: 1. A screen overlay generator to display map legends at a defined location in the GE window, as opposed to being fixed to the ground surface, 2. An orientation symbol generator that places 3D bedding, foliation, or lineation symbols hovering just above the GE terrain surface, and 3. A cross section tool that takes PNG images of cross sections and positions them as vertical models on the GE surface. The HTML interface allows geologic map builders to incorporate these advanced features without KML scripting or COLLADA model design. Comments and suggestions for improving and augmenting these tools are welcomed, with the goal of encouraging members of the geoscience community to create their own interactive geologic maps in Google Earth.