[This code is experimental! Your mileage may vary!!] Dual_Color_SRTM_and_GPX_to_STL builds on the code in SRTM_to_STL_1 This code will convert NASA SRTM (1 arcsec) data and a GPX track/route file into two separate STL files which can be 3D printed in two colors - the idea being that the GPX route you followed can be printed as a second color, embedded in a 3D landscape created from NASA SRTM data. If you aren't interested in dual color printing, have a look at SRTM_to_STL_1 or SRTM_to_STL instead. The SRTMGL1 data can be downloaded from: http://earthexplorer.usgs.gov/ Select the data set called NASA LPDAAC Collections \ NASA SRTM (SRTM 3) Collections \ NASA SRTM3 SRTMGL1 The 1 arc-second data has a horizontal resolution of about 30m on the ground and is best suited for printing relatively small areas at maximum resolution. You can still join the hgt files together (with SRTM_Join.py) if the area you are interested in crosses file boundaries, but the software will then ask you to cut the data leaving 3601 x 3601 points. If you want to print large areas, you will probably be better off using "SRTM_to_STL". You can still use the 1 arc-second data, just use SRTM_resample.py to convert the 1 arc-second data files into 3 arc-second. To create a nice print of the summit of Everest with an approximation of the route followed by Tenzing Norgay and Edmond Hillary in 1953 in a second color: The 1953 route for the ascent of Everest is inspired by the map shown on page 9 of: http://www.rgs.org/nr/rdonlyres/22a09637-b5c9-4c44-8110-77126083ded9/0/everest53.pdf Everest straddles N27E086.hgt and N28E086.hgt, so use SRTM_Join.py to join the files together: python SRTM_Join.py N27E086.hgt N28E086.hgt The code will ask you which row you want to cut from. Enter "1800" You need to keep a note that the file now has a latitude offset of 0.5 degrees SRTM_to_NPZ.py then converts the hgt file into numpy .npz format: python SRTM_to_NPZ.py N27E086_join.hgt Remember to enter the latitude offset of 0.5 The npz file contains: width, height, hgt_max, east, north, hgt Where: width is the width of the data in eastings (columns) height is the height of the data in northings (rows) hgt_max is the maximum altitude in the data east is the array of eastings north is the array of northings hgt is the array of altitudes UK data is converted to OSGB coordinates using WGS84toOSGB36 Data for the rest of the World is converted to UTM The npz file can then be trimmed to our area of interest: python NPZ_Trim.py N27E086_join.npz 487000 496000 3091700 3100700 (This trims the npz file to a 9km x 9km area centred on the Everest summit) (The trimming takes a long time - there must be a more efficent way of doing it!) The .npz file is then converted to .stl: python Dual_Color_NPZ_to_STL.py N27E086_join_trim.npz 87.5 90.0 Enter 0.0 for the base offset and base thickness to create a true 1:100,000 scale print. You can save plastic by entering a base offset of -50.0. The code also creates a file called 'STL_Params.npz' which defines the size and scale of the landscape STL file so the GPX route STL can be created to the same size and scale. Dual_Color_GPX_to_STL.py then converts a GPX route for the same area into a separate STL file which can be printed in a second color: python Dual_Color_GPX_to_STL.py Everest_1953_Route.gpx n 2.0 The GPX track/route points (lat and lon) are converted to UTM, then converted into a DXF file (arcs around each waypoint with lines between). OpenSCAD first converts the DXF file into a 2D solid and then linear_extrudes it to a height beyond the maximum in the landscape. Finally OpenSCAD calculates the difference (color 1) and intersection (color 2) between the landscape STL and the GPX STL. OpenSCAD can be downloaded from http://www.openscad.org/downloads.html You will need to modify the string "openscad" in Dual_Color_GPX_to_STL.py if you install OpenSCAD anywhere other than C:\Program Files\OpenSCAD dxfwrite gratefully downloaded from https://pypi.python.org/pypi/dxfwrite/ utm has been gratefully plagiarised from https://pypi.python.org/pypi/utm and then modified to allow the UTM zone to be forced. This is essential if the hgt data crosses or ends on a UTM zone boundary. See http://www.dmap.co.uk/utmworld.htm WGS84toOSGB36 is gratefully plagiarised from: http://hannahfry.co.uk/2012/02/01/converting-latitude-and-longitude-to-british-national-grid/ This is an artistic project. If you are intending to climb Everest, you will need better maps and data than this! Please accept this for what it is: an approximation of the 1953 ascent of Everest. If you have enjoyed this code, please make a small donation to: http://himalayantrust.co.uk/donate/