How to get free topographic map into Garmin eTrex 20

This post will guide you on how to download the SRTM3 data to create a topographic contour map to complement your existing Garmin street maps in your Garmin eTrex 20 GPS device. You will use it like an extra layer of map on top of your existing Garmin street map.

If you have not got a street map and you are interested in getting the street map for your Garmin eTrex 20 device, please refer to How to get free routable maps into Garmin eTrex 20. 

If you are interested to get street maps for Malaysia and Singapore, please refer to How to install malfreemaps into Garmin eTrex 20. Malfreemaps provides a very comprehensive map of Malaysia and Singapore, more comprehensive map than the free OpenStreetMaps.

Note: The steps below only applicable for Windows OS and make sure you have Java installed into your system.

Steps

1. Download OSM2GarminTopo. This is a zip package that i have packed with mkgmap, srtm2osm and my custom batch script to automate the creation of the topographic map layer.
2. Extract the content of the zip file out.
3. Goto http://touren.mospace.de/kachel.html, select an area using one of the techniques described there, tick the "Elevation contours" checkbox, and hit submit.
4. You will get a list of download links for *.img.gz files and a list of srtm2osm command lines at the bottom part that looks something like this:
   
   srtm2osm -bounds1 47 8 48 9 -o 53273978.osm
   srtm2osm -bounds1 48 8 49 9 -o 53273979.osm
   ...
5. Open my custom batch script (BuildTopo.bat) with notepad or any plain text editor.
6. Copy the list of the srtm2osm command lines from the webpage and paste it into my custom batch script (BuildTopo.bat). Paste it under these lines:
   
   rem paste the list of srtm2osm commands under the line below
   rem add % at the from and back of srtm2osm for every line
   rem example %srtm2osm%  -bounds1 4 99 5 100 -o 53290315.osm
   rem --------------------------------------------------------
7. Add "%" sign at the front and back of the "srtm2osm" for every line.
8. Add a map description of your topographic map to the line:
   
   set MAP_DESCRIPTION=
9. Save the batch file and close your text editor.
10. Open a command line window and cd to the OSM2GarminTopo folder.
11. Type BuildTopo.bat and hit enter to start the creation of the topographic map.
12. Rename the generated gmapsupp.img map to any name that is meaningful to you.
13. Transfer the IMG file into your Garmin eTrex 20 device.

You should be able to enable or disable the topographic map from the map setup of the Garmin eTrex 20 device. The name of the map stated in the setup will show the map description you have set in step 8.

References or Credits:

1. http://wiki.openstreetmap.org/wiki/Topographic_maps_for_garmin_devices
2. http://touren.mospace.de/kachel.html
3. http://www.mkgmap.org.uk/
4. http://wiki.openstreetmap.org/wiki/Srtm2Osm