In order to help local tourism services, La Vilaine Bidouille, the FabLab from Redon in Britanny, had to study the possibility to print in 3D our little French Far West. We found topographic data form satellite on the Web. Then we used Blender to turn these data into a 3D printable solid.
The tools used here are : Blender, Gimp and MicroDEM (from the US Navy)
Step 1: Step 1 : Get Topographic Data
We went on the SRTM website. We choose the map part with the west part of France.
If you want to follow this Instructable to the end with the same tools, you need to choose the ASCII format when you download the map.
Step 2: Step 2 : Convert Satellite Data Into Shade of Gray Picture
A shade of gray picture codes each pixel from 0 (black) to 255 (white). The great advantage of this is the fact that this kind of data are very easy to handle.
Let's convert the raw data. We unzip the file downloaded on SRTM website. And we open the *.asc file with MICRODEM (open>open DEM).
The picture we obtain is a nice Brittany including the Mont Saint Michel (supposed to be in Normandy). Trust me, it is matter in France. So, we need to cut the picture using the "Subset" function.
Right-clic on the map. Choose “Legends/Marginalia” to unselect any legend and grid. But we still have colors.
Right-clic ont the map again. Choose “Display parameter>Elevation>Gray scale”.
Save the picture in your favorite format with “File>Save Image”. My favorite one is PNG because I like it.
Step 3: Step 3 : Resize the Picture
Quit MicroDEM for GIMP.
Sometime the sea is white at this step. In this case select the sea and turn it into black.
If your french, as we are, you will probably use IGN data (BD ALTI 75m) instead of SRTM. The color of the sea will be black in this case.
Anyway. On GIMP use the function Image>Canevas Size... and change the size into 800x800 pixels. That's all for Gimp. Sorry for anyone who expected a tuto on Gimp.
Step 4: Step 4 : 3D Model on Blender
Hard part. Open Blender before you get scared.
Delete everything on Blender. Press "a" then "x" and confirm.
Then we create a grid. In order to have objet light enough to be handle by a standard PC, we use one vertex per two pixels. Our grid must be 400x400. Press "Shit+a">"Mesh">"Grid". And before doing anything else, in the bottom left menu, we define the grid divisions numbers.
Belgium ! Our grid is flat.
Right-clic on that grid to select it. To have relief, we will add a "modifier" to the grid. Look at the top-right menu.
A "modifier" is like a little sub-program that changes the selected object. It looks complicated but we are lucky. One of the standard modifiers do exactly what we need : change the height of a vertex according to the shade of gray of pixel in a picture.
"Add Modifier">Third column>"Displace".
Create a texture pressing "New". Edit that texture pressing the little button (look like nothing) at the right of the texture name. Into the sub-menu "Image", "Open", then choose our map picture. Into the sub-menu "Image Mapping", choose "Clip".
Come back to the Modifiers menu (looking like a tool) and "Apply" the modifier.
Now our 3D object looks close to our goal. Press "g" to move the object, then "z" to lock the direction, and, place the object above the ground zero.
Cool but not printable. We need to change this surface into a solid. Press "Tab" to edit the object vertex. Switch in "edge" selection. Select all vertex pressing "a". In bottom menu, use "Select>Select Boundary Loop". Extrude the boundary pressing "e" then "z". Now move down the boundary with the mouse.
The bottom of our object is not flat. Tip & trick : Put the cursor to 0,0,0 pressing "Shit+s">"Cursor to Center...". The boundary is still selected. Scale it to zero pressing "s", "z", "0".
To close the bottom, press "F". Press "Tab" to exit the object.
Right-clic on the object. And export it in STL. That's it.
Step 5: Step 5 : Print Brittany in 3D
The STL file can be printed on any 3D printer. Use the scale function of your favorite printer software.
The Blender part is not easy. For french makers like us, you can read a great book about blender : "La 3D libre avec Blender" from Olivier Saraja. If you already know Blender, Olivier Saraja has also written another great book , "Zombie Kebab", that is cheaper than the first one.
If you want to see the finished printable Brittany, go to my Sculpteo collection.
Try with your own country.