DOES 3-D MAKE IT BETTER? USING 3-D PRINTED TERRAIN MODELS TO ENHANCE UNDERSTANDING OF TERRAIN SHAPE AND FORMATION

Analysis of terrain shape as a clue to underlying formation processes is a common theme in geoscience courses, applicable to topics from volcanology to structural geology to planetary science. Often we present these concepts using two-dimensional representations such as topographic maps or digital elevation models, which may be unfamiliar to a typical introductory student who must first learn to interpret these maps/images and then apply the concepts. One way to bridge this gap may be the use of 3-d printed terrain models as an "answer key" for interpreting topographic maps/images, practicing calculations such as vertical exaggeration and scaling of model to map distance, and relating to underlying geology.

For this work, 3-d models were created multiple workflows, as no one single pathway produced ideal results. Digital elevation models were sourced from online repositories (the National Elevation Database [https://lta.cr.usgs.gov/NED] or the USGS Planetary Image Locator Tool [https://pilot.wr.usgs.gov/]) and subset to the appropriate features using GIS/remote sensing applications (ArcGIS, QGIS, ENVI). These subsets were then converted to image meshes using QGIS v.2 (via the DEM23D plugin), Python (via dtm2obj, a script written by J.A. Richardson [https://github.com/jarichardson/dtm2obj]), or the 3d Surface Model option in ENVI (a commercial application from Harris Geospatial). Meshes were processed for printing using freely available software tools (Ultimaker Cura, MeshLab, Autodesk Meshmixer, Slic3r) and were printed on a Prusa Mk3 (but would be appropriate for other printers or a printing service).

Models will be deployed as part of in-class exercises in introductory geology and planetary astronomy courses; exercises will also utilize printed versions of DEMs and additional information such as hand samples and geologic maps as appropriate. Students will be asked to identify if/how the 3d models were useful in completing the required exercises as part of the assignments. Targeted concepts include the shape of common volcanic landforms and the relationship to magma composition and eruption style, determining the geologic history of a region using topography and structure, how impact crater size influences shape, and how elevation and terrain differ on either side of the Martian hemispheric dichotomy.