TouchTerrain

• Communicating the 3D nature of terrain is fundamental for many geosciences, yet difficult to achieve with 2D contour maps. Using 3D-printed terrain models can help reduce this cognitive burden.
• TouchTerrain ( touchterrain.geol.iastate.edu ) makes it easy to produce 3D-printable terrain models for any area on Earth, including the ocean floor.
• To select the print area, users can use a search box, pan/zoom to it on a Google Maps-style map, or upload a KML file with the area's outline.
• 3D print options specify the physical 3D model's size (in mm), whether to tile the model into multiple sub-tiles, its base thickness, and its vertical exaggeration (z-scale).
• For verification, an in-browser 3D visualization is shown prior to downloading the generated 3D terrain model.
• Expert settings include setting a specific geographic projection and ignoring areas below sea-level.
• TouchTerrain can also be run as a standalone Python program (and within a Jupyter notebook) on a local computer where, in addition to the online DEM sources, local geo-tiff DEM files (e.g., LiDAR terrain) can be processed. A docker version of it is  here .

• Ease-of-use: From handling and examining everyday hand-held objects, humans are already familiar with how to "navigate" (zoom, rotate, pan…) 3D terrain models and visually explore them from different angles. This ease-of-use compares favorably to the often-cumbersome interaction with digital 3D graphics models via computer or 2D paper topographic maps.
• Touchable: physical terrain models offer a tactile experience; most people, when given such a model, instinctively run their fingers over it. This multi-sensory combination affords users a richer and more natural exploration of the elevation data.
• Front loading all technical aspects: although both the creation of the digital 3D model and the 3D printing process require some technical skill, interaction with the resulting physical object is simple and requires no technology or training.
• Educational: In the classroom, 3D printed terrain models can be used in conjunction with paper contour maps of the same area to help students better understand the fundamental principles of contour maps.
• Outdoor use: 3D-printed models are cheap to print and sturdy enough for use on field trips to illustrate features of the surrounding terrain, for example. They can be sprayed with primer and annotated in the field.
• Unique connection: As physical, tangible objects 3D-printed terrain models can provide an emotional attachment to a place or area that digital or paper formats lack. Many TouchTerrain users report printing the areas they live in, places they often hike, favorite travel destinations or childhood hometowns.

• The digital model is defined as a 3D mesh of triangles inside a 3D CAD model file (STL; left).
• The slicer software prepares the model for 3D-printing by creates horizontal profiles (slices) through the model (center).
• The 3D printer itself moves a ~210°C nozzle (with an orifice ~0.4 mm in diameter) in the horizontal (x/y) plane according to the tool path lines of each slice.
• After each slice, the nozzle is moved up 0.3 mm and proceeds to print the next slice.
• Each layer is extruded on top of the previous layer and fuses with it as it cools, thus slowly creating a 3D physical object out of 2D slices (right).

Here are a few examples of 3D printed terrain:

This Web Scene shows areas that have been popular for creating 3D terrain prints from

For more information about the TouchTerrain project, see our free-access paper  TouchTerrain—3D Printable Terrain Models  in the International Journal of Geo-Information ( https://doi.org/10.3390/ijgi10030108)   and  our blog .