3D Printed Topographic Map

Perfect for interactive teaching, artwork to gift or keep, or even just to show off what your 3D printer can do, making a 3D printed topographic map is easy with these simple steps. You'll need a 3D printer (obviously), any laptop, and a couple of free applications downloaded. Thanks to open-source DEM (Digital Elevation Model) data, you can print the topography of anywhere in the world.

Step 1: Get Elevation Data

You can get your elevation data from anywhere, but one source I've had a lot of success with is opentopography.org. It has DEM data for the entire surface of the Earth at 30 meter resolution, as well as many places down to centimeter resolution. If you have a .edu email address, you can get large swaths of high-resolution data for free, but if you don't you can still get quality DEM data for almost anywhere.

To get data for the location you want, make an account then go to Data->Find Data Map and select a box around the location you want to print. Below the map window will appear a list of data sources. Clicking on the link in the blue box on the right of each data source will take you to its page that shows its extent on the map. Open Topography will give you every data source inside the bounding box you created, and while it may be possible to piece together different data sets, it is much easier to either choose the one with the largest area or select from one of the global data sets. The global data sets are at a lower resolution, but will cover the entire box. If you're printing a map of something similar in size to a city, you can probably get away with the lower resolution.

Once you've selected your data source, make sure the data output format is GeoTiff and give your job a title then hit submit! In a few minutes you will get an email with a link to download your data in .tif format.

Step 2: Combine and Edit Elevation Data

To clean up the data and make it easier to print, you can use an application called QGIS (download here for Mac and PC). It can edit the GeoTiff format and export in a format readable by a Fusion 360 plugin. To import your data, create a new project and add a new layer by selecting Layer->Add Layer->Add Raster Layer. In the source box, select the .tif files you downloaded from before and click Add to import them into QGIS.

If your DEM data came in multiple .tif files, you'll need to merge all the tiles of data together. You can do this by selecting Raster->Miscellaneous->Merge and selecting all of your imported layers.

If your data goes below sea level and you'd like the ocean to be flat so that you only show land, you can set the minimum elevation to 0 by selecting Properties->Symbology->Min and setting it to 0.

If you'd like to accentuate your land area to make it clear what is land and what is water, you can change all values of 0 or below to be a constant negative value. This will print the topography with a ridge along the coast. To do this, select Raster->Raster Calculator, then enter ("LAYER">0) * ("LAYER") + ("LAYER<=0)*(-30). You'll need to replace "LAYER" with whichever combined layer you are working with. You can change the value -30 to any arbitrary value to get a higher or lower drop at the coast. It will set all 0 or negative values to the constant -30.

Step 3: Export Elevation Data As Image

To import into Fusion 360, you will need to export the DEM data as an image. So select Project->Import/Export->Export Map to Image and select "Draw on Canvas" to choose the extent of the export. You'll then need to draw the rectangle of data that you want to export. If you're trying to print a dimensionally accurate map, you should grab either the North/South or East/West extents here. You'll also need the minimum and maximum elevations (the two numbers under the layer name on the left bar). Hit save to save it as a png and you're good to go.

Step 4: Use Image2Surface in Fusion 360

Fusion 360 is free to download (from here) and easy to set up. Once you have it installed, you will need to download the plugin (from here) and install it using these instructions. Open the plugin by going to Tools->Add-Ins and selecting Image2Surface. Then select Choose File and select your image to import it into the plugin. You can then vary a few parameters to get your perfect topographical surface.

The first, "Pixels to Skip", indicates the effective resolution of the resulting surface in Fusion 360. Higher number = lower resolution but faster processing time. I would recommend somewhere between 3-5 for this value, but if you find its running too slowly or you want higher resolution you can tinker with it one way or the other.

The second, "Stepover", will determine the x-y dimensions of the imported surface, essentially how close together the pixels of the surface are to each other. This will depend on how large you want the model and how big your print volume is.

The last, "Max Height", is exactly what it sounds like. I usually play around with this after settling on the first two parameters to see what height would feel right for an exaggerated topographical map. If you want a to-scale map (which is much more boring for large sections of geography), you can calculate the approximate scale max height by looking at the dimensions under "Surface Information". You'll need to calculate the mm per meter (or other unit your DEM data came in) by dividing the length or width of the printed surface by the North/South or East/West distance covered by the DEM data. Then take that number and multiply by the difference between maximum and minimum elevation to get the effective max height in millimeters for the surface.

Step 5: Convert Surface to TSplines

Once you've imported the elevation data into Fusion 360, you'll need to convert the surface from a quad mesh to T-splines. Click Create->Create Form then Utilities->Convert. Select Quad Mesh to T-Splines from the dropdown then select the mesh surface and hit ok. This may take a minute to compute, but the appearance of the surface should change. Then select finish form and it should change again. If either of these steps are taking too long, you likely need to increase the "Pixels to Skip" value from Image2Surface. Unfortunately, this requires force-quitting Fusion 360 if it is stuck, or at the very least restarting the model, but it will save you the major headache of freezing your computer for hours while it slowly loads.

Step 6: Extrude Solid and Edit CAD Model

Once you have your T-Spline surface, create a sketch of a rectangle with the exact dimensions of the outside of the surface. Then, extrude the rectangle using the to-object extent, selecting the T-Spline surface as the object. Sometimes it will give you an error at this stage since it could be extruding to a surface that is in the same plane as the sketch. In this case, you can set the start plane as offset something like -2mm to ensure there is a base with nonzero thickness.

After this step, you can add/edit the solid in any way you'd like. You can add extruded text to add a title. You can cut out sections of the geometry to print in two different colors. You can even model houses or ships on the topography to give it more scenery.

Step 7: Export As STL and Slice

Once you have your finished CAD model, export it as an STL and import it to your preferred 3D printing slicer. Right click the extruded body from under "Bodies" and select "Save to STL" with low resolution. Then import to a 3D printing slicer like Cura and export as Gcode. I've found that any layer height up to 0.2mm works to make out most fine details in my maps, but scale that value as you see fit!

Step 8: Print!

Lastly, print it! And there you have it, a finished topographical map of anywhere you want!