First, we need to obtain DEM (digital elevation model) data, which we can get from USGS. You can enter coordinates or draw a box as seen in the image below:



Finally on the left hand side of the page you can checkout, which will ask for your email to send you a link to download.

Next Open Sculptris, which we will be using because it can handle more geometry and is faster. See the image below for help with the steps.

1. Replace the sphere with a plane - because the world is flat
2. Turn off symmetry - we don't want it
3. Subdivide the plane a few times (like 5) - the more subdivisions, the more detail
4. Upload your height map image for the brush and make sure to enable it
5. Adjust the size, strength, detail, etc.
6. Zoom to the correct distance, get a top view, click once, and export it. (this may take a few atempts to get right)

Next we will use Blender to make this model 3D Printable. First we need to convert the model to an stl format. We can do this by importing our model from Sculptris into Autodesk Mesmixer. Then export the model out of Meshmixer and import it into Blender. Once imported in Blender:

1. Go into Edit Mode [tab] (convert triangles-->squares with alt+j)
2. Select the Edge Loop [alt + right click] 
3. Extrude [E]
4. Flatten out the vertices [S+(X,Y,orZ)+0]
5. Fill in the hole [F]
6. Export your model that you can now print!

Hint: You may want to add a smooth modifier if your model has a lot of noise.

Note: This could have all been completed in Blender starting with the JPEG image found in the downloaded folder. You would open Blender and then use the displace modifier on a subdivided plane, see this tutorial for info on how to. But Sculptris handles the detail better without crashing as Blender would have.

I used ArcMap (not free), an Esri GIS product to import the DEM information. I unzipped the file and then imported the raster dataset.

Finally export the model as an stl.

The model may have non-manifold errors (holes, separate parts, etc.) This is the hardest step in the process and will require an understanding of non-manifolds. Perhaps the easiest method is to upload the model(.stl) into the netfabb cloud, although this may not work. If it doesn't then you will need to try other methods found in the following post. I would start with Meshlab. An easy way to see the errors is in Meshmixer as seen in the image below.

• Automatic Methods
• Manual Methods 

Also one method may not be enough, as multiple methods may be needed to fix the model.

If you do not do this step then your model may not 3d print properly.

You may need to choose a side for the supports to be printed on. This should probably be the side that you care the least about the appearance of. You may also need to orient, scale, split, add a raft, etc.

It should be noted that these models are often complex and can take days to print, so make sure you are not on a deadline to have it printed. Also note that it may take a couple of hours for this model to slice alone.

If you do not have a printer check out 3D Hubs to get your model printed in sandstone (full color).

http://www.thingiverse.com/thing:15276/#instructions

Please leave your comments.

and as always thanks for visiting,
The 3D Printing Ninja

3DNinjaneer@gmail.com