TouchTerrain: A Web App to Easily Make 3D-Printable Terrain Models

Chris Harding (Geological and Atmospheric Sciences, Iowa State University) and Franciszek "Franek" Hasiuk (Kansas Geological Survey, University of Kansas)

Reformatted version of a poster exhibited at the AGU conference in December 2020.

Quickstart

1. Go to touchterrain.org

2. Select the area you want to print on the Google Map

3. Define the physical dimensions of the 3D printed model

4. Check the model with the interactive 3D terrain previewer

5. Download the STL file and 3D print your terrain model from it.

Background

· Communicating the 3D nature of terrain is fundamental for many geosciences, yet difficult to archive with 2D contour maps. Using 3D printed terrain models can help to reduce this cognitive burden.

· TouchTerrain (touchterrain.geol.iastate.edu), launched in 2017 and currently at version 3, allows non- experts to use a simple web-mapping interface to produce 3D-printable models of the terrain of any area on Earth, including the ocean floor. Several online elevation data sets are available (e.g., 10m US DEM, ETOPO 1km grid globally).

· Users can pan/zoom to an area of interest on a Google Maps-style map, visualize the terrain as a transparent hillshade overlay and adjust its viewing parameters (transparency, sun direction, sun angle, and gamma). Numerous 3D print options are provided to support the user’s specific 3D printer model, including the physical 3D model size, whether to tile the model into sub-tiles, its base thickness and its vertical exaggeration.

· For verification, an in-browser 3D visualization is shown prior to downloading the generated 3D 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.

· TouchTerrain is a collaborative open source project, for details see github.com/ChHarding/TouchTerrain_for_CAGEO/.

Why use 3D printed terrain models ?

· Most terrain models printed on today's consumer-grade 3D printers are between 10 cm and 40 cm square. From handling and examining everyday hand-held objects, everybody is already familiar with how to "navigate" (zoom, rotate and pan) the 3D terrain model and visually explore it from different angles. This ease-of-use compares favorably to the often cumbersome interaction with digital 3D graphics models via computer.

· In addition, 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 represented by the 3D printed terrain model.

· An added benefit of 3D printed terrain models is a "frontloading" of all technical aspects: although the creation of the digital 3D model does require technical expertise in GIS, etc.; and the 3D printing process requires the know-how and equipment to operate the 3D printer, interaction with the resulting physical object is simplicity itself and requires no technology at all.

· The core ambition of the TouchTerrain project is to minimize the technical GIS expertise when creating the digital 3D models that are later given to the 3D printer. With TouchTerrain, no GIS expertise is required, simply select the desired area and download its 3D terrain as a STL/OBJ file.

· 3D printed models are now cheap to print and sturdy enough for use on field trips; e.g., to situate students within the surrounding terrain. They can be sprayed with primer and sketched on in the field.

· 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.

· Finally, as tangible, physical objects 3D printed terrain models can provide an emotional attachment to a place or area that digital formats lack. Many TouchTerrain users report printing the area they live in,

go hiking, travel to on vacations or lived in as a child.

The 3D printing process

· Starts with a triangle based 3D CAD model file (STL)

· The slicer software creates horizontal profiles (slices) through the model at ~0.3 mm intervals, from bottom to top.

· Slices consist of many 2-D tool path lines

· Each slice uses walls to define the outside and an infill pattern for the inside of the model

· The 3D print hardware moves a ~210°C hot nozzle (typically 0.4 mm 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 processes the next slice

· In FDM (fused deposition modeling) 3D printing this nozzle extrudes hot plastic filament, which cools to form a solid layer. Each layer is extruded on top of the previous layer and fuses with it, thus slowly creating a physical object.

· Animation of the process

· Timelapse of 3D printing with a delta printer (uses Octolapse)

· YouTuber creates a continent scale terrain model of the US using TouchTerrain

TouchTerrain Web App walkthrough

Defining the area to print

· Option 1: Manually navigate the Google map to the area, click Re-center box on map and adjust the red box manually (video)

· Option 2: Use the Place search bar on the top to fly to the place, click Re-center box on map and adjust the red box manually (video)

· Option 3: Click on Area Selection Box and manually enter the four lat/long coordinates of the box corners, hit the Enter key after each entry. (video)

· Set the value of 3D printer resolution to the diameter of you printer's nozzle, typically 0.4 mm. Using a lower value does not increase your print's detail and will only result in larger STL files. (video).

Setting a smaller layer height (e.g. 0.2 or 0.15 mm) in the slicer settings will get you better detail but will take longer to print

· Decide if you want to divide your area into multiple tiles. Each tile has the width/height and print resolution set earlier. The dimensions of the 3D printed tiles will fit together perfectly and can be glued together to a form a single, larger model. (video)

· Select the Model Base thickness. This defines how high a base will printed before the actual elevation model starts. 0.5 mm is typically enough to ensure that the very lowest parts of your model (e.g. a river) do not end up with too few layers when printed and may become "see-through (video)

· Set the vertical exaggeration (z-scale). This will multiply the terrain elevation by this factor, e.g., a z-scale of 2 would double the elevation and give you much "steeper" terrain. Using a zscale > 1 is recommended when printing low-relief terrain in order to have at least 50 layers to print with (video, with comparison example)

· For File Format, STL binary (smaller filesize than STL ascii or OBJ) is an extremely common triangle model format for 3D printers. OBJ format is sometimes preferred for working with 3D modeling software.

· There are more options you can enter into the manual options field and are described here under Processing Parameters. This video shows two manual options that can help to print better shorelines.

Previewing and downloading the model

· With all options now set hit the green Export button to create your model file. Marvel at the animation while your model is processed.

·

Once processing is done you'll be able to preview your STL (video). If you're happy with the model click Download zip file.

· The zipfile will contain a STL file (multiple files for multi-tile models), a detailed log listing all options used and processing steps taken and a GeoTIFF of the terrain suitable for import into a GIS program.

· Finally, you will be shown the URL for this model with all settings it used. This can be handy if you want to "bookmark" your print or email it to others.

o Site usage is worldwide:

o 48% of users are from the US, most from major cities:

Usage type (from the optional feedback: "tell us what you're using this model for"):

o 9.33% of users leave some form of feedback

o Feedback indicates that TouchTerrain is used in education, for outdoor trips and for creating models of familiar areas.

Here are some examples of the feedback received:

o For my wife's Earth science 11 class.

o 3D print for use in a hands-on, 4th grade science unit about flood and drought, looking at a local watershed.

o Tangible maps for daughters kindergarden class can use

o Elementary School education

o For my Grandson School Project

o I want to make a science project about volcanoes

o 4th grade landform project

o Middle school 3D printing class example. Students will each export and print their own terrain.

o Teaching oceanography course: section on coastal geology

o Glacial Flow modeling

o Teaching geomorphology

o Geological reference

o Research in geographical data types and elastic displays

o For a museum to illustrate how increased tides will effect the waterfront area in Kingston, NY

o Meteorology training

o Paragliding training

o Planning ski routes

o To help understand radio coverage in the area

o To map sacred sites in Kenya

o Examining topography in North American Monsoon region

o Secondary Earth Science instruction

o College physical geology class

o History class, I am a teacher

o A fab lab class activity

o 3d printing maps for exploring the White River for visually impaired folks in northwest arkansas

o I print ski resorts so you can see the mountain from a new perspective!

Teaching my kids their surrounds, way to svhool, beach, woods we visit

o For my dads distract so ist can help him describe wehre fires are located in his distract

o Just wanted to print the local area on my 3d printer

o I am first year architecture student, Struggling with site model. We were asked to trace old map isocurves and then lift them at elevation

o 3rd year industrial design project

o 3d printer to create a topographic map of our campus.

o Snowmobile zone mapping

o Lifeguard training

o Flight training

o Ham radio club

o Looking to land to build retirement home

o To better understand my property.

o Elevation comparison in my town

o 3D printing Kauai island since we can't travel there currently

o Just a personal print to map hikes we do in the Tetons.

o Mountain bike trail map

o Trailrunning

o For making a jigsaw puzzle.

o A gift for Grandma

o To match with drone footage

o Make into a trophy for beer Olympics

Places searched:

TouchTerrain Version 3 added a place search field. These are the top 25 searches since October 15, 2020

Some tips for 3D printing terrain

· This assumes that you are already familiar with 3D printing in general and know how to change settings in your slicer

· Lay your terrain model flat on the buildplate, that way the layering will look like contours

· A layerheight of 0.2 to 0.3 is typically good enough

· However, make sure that you have at least 50 layers, otherwise your print will lack detail. Either use vertical exaggeration or scale it later in the slicer to about 50 x layerheight (e.g.: 50 * 0.3 mm => your model should be 15 mm tall)

· 10% infill it typically enough, but make sure you have at least 3 top layers

· Use a 7 - 12 mm brim, a heated bed or even an enclosure (hood) to avoid curling on the corners and edges

· Instead of the typical line type use a concentric fill pattern for your top (skin) layers. This will avoid artificial looking stripe patterns, which are especially obvious on flat terrain or lakes

· Set combing to only within infill to avoid ooze tracks

· PLA and PETG are perfectly suitable to terrain models, but ABS may warp without an enclosure

· Printing terrain generally requires very little part-cooling which also promotes layer adhesion. However, good part cooling should be set for very short layer times (e.g., for small peaks) to prevent stringing

· For post processing, brushing the top with a wire brush is usually enough to remove any stringing. A hot air gun is more effective but can easily warp your model when used for too long!

· 3D Prints are typically somewhat glossy. If you prefer a matte finish or want to be able to paint or draw on your model, spray the model with gray automotive primer filler. After this you can use a soft pencil or Sharpie to draw on them and use a dry eraser or rubbing alcohol to remove drawings. Do NOT use nail polish remover (acetone) as this will deform the surface!

· Gray filament seems a good compromise to still bring out details in dim lighting conditions (e.g., classrooms) but metallic looking filament can produce very artistic results

· Use superglue gel(!) for gluing together multiple terrain tiles. To mount the terrain on a wooden plate, use a hot glue gun, which later can be removed with alcohol.

(last edit Jan. 8, 2020)