CONSTRUCTION AND PRESENTATION OF GOOGLE EARTH MODELS FOR UNDERGRADUATE GEOSCIENCE EDUCATION

Earth and planetary sciences are concerned with spatial and temporal data on scales that are unfamiliar in daily life. Helping students to understand processes occurring extremely slowly or at great depth is essential for enhanced learning outcomes in undergraduate geoscience courses. We here present methods for constructing and deploying Collada models of planetary interiors created in Google SketchUp. There are three alternative approaches to representing solid geology using Collada models in the Google Earth virtual globe. The first approach causes subsurface geology to emerge from beneath the surface of the globe using a slider control. This has very definite benefits in helping students understand where subsurface data comes from but the stand-alone application has only one time-slider control and conflicts can arise when multiple models are loaded simultaneously. The second approach is to render the terrain surrounding a model transparent thus revealing a crustal or mantle block in situ. This works reasonably well despite minor rendering issues but requires specific user actions that cannot be pre-coded and thus may require extra student supervision. The third approach is to use the newly released Google Earth API in place of the stand-alone application. This allows the virtual globe to be embedded in a HTML document and viewed with a web browser after installation of a plugin. The plugin is freely available for Mac and PC (but not yet Linux) and instals in common browsers including Firefox, Safari, Chrome, and Internet Explorer. With this approach, the plugin can be installed before class leaving students with a familiar web interface. Collada models in the API virtual globe can be made to respond to several javascript-based user interface elements, including, sliders, buttons, and text fields. Thus it is possible to control not only the elevation of a crustal model, but also the time period it represents and multiple other features. Sample applications include the restoration of geologic cross sections in situ in the virtual globe, and the loading of alternate tectonic models for comparison of competing hypotheses. Finally, model appearance and data can be controlled remotely by the instructor using network links. These can be employed to simulate geological events or to introduce test questions during classes.