Readme : MAPC2MAPC

The main reason for writing this program was to make maps portable between different GPS Systems. I was travelling to Spain and wanted to use a free map based on an obscure (to me) datum with Memory-map. I then calibrated an on-line street map of Nerja to find my way around the narrow alleys there, and so on.

Most GPS sytems work on the basis of an image file (usually .png bit also .tif, .jpg and others) and a calibration file which associates points of the map into the real world. Image files are to a common set of standards but there are many different calibration files and I have tried, by providing a means to convert from on to another, to allow the same maps to be used by several systems. This is not about hacking, just making a fiddly manual process easier and more reliable.

Sadly, some GPS system makers don't (or won't) understand portability. Satmap, Anquet and several others will only load maps in their own proprietory format. If they can supply all the maps you'll ever need at a cost you can afford then that's fine.

For everyone else, here are some ideas and pointers to sources of maps.

Lots of programs work with the .map calibration files used in OziExplorer. Gmapmaker, for example, downloads maps from Google, OpenStreetmap and other sources and will produce a .png image and a .map. MAPC2MAPC will convert that .map file to other formats (e.g .jpr for Memory-map, .cal for Pathaway).

There is a large collection of Spanish maps at 1:50,000 and 1:25,000 here. After registering your name, start to download excellent maps (link to: Información geográfica digital con licencia de uso no comercial). The maps are available as TIFF files with a TFW calibration file. The projection is UTM, so when opening the calibration file choose the appropriate zone (28, 29 or 30 depending on the area)

Maybe you have a map that is too big for your portable device. MAPC2MAPC will shrink it and/or crop it whilst producing calibration files to match the new size. Or if you have several maps you want to join together (even if they have different scales or Datums) the MergeMaps function will do this.

Garmin announced the availability of "Custom Maps" in October 2009 where certain models will display digital maps. MAPC2MAPC will create a map in the correct .kmz form. The map does not have to point North-South and can have any of the supported Datums or calibration files. Images are automatically converted to the required .jpg. There is an animated guide here.

Google Earth with image overlays provide a quick way to calibrate maps. Align the image over google Earth and save as a KMZ. MAPC2MAPC will create calibration files from this (e.g for OZI, Trekbuddy or Memory-map) - or split the map into a KMZ as tiles to make a Google Custom Map (otherwise you have to split the map yourself and align each tile).

For the US, there is a big set of free maps at Libre Map Project. These come as .tif with .tfw calibration. MAPC2MAPC will convert the .tfw to .map (etc) allowing these maps to go into OZI, Memory-map etc, or converted to Garmin Custom Maps - example here. In Canada, there is Canmatrix. These maps are GEOTIFF where the .tfw is embedded. It can be extracted by FWTOOLS and then converted.

Maybe you have some favourite tracks that you want to record on a map. MAPC2MAPC will load TXF and PLT files and draw them onto a calibrated map which can then be saved.

I recommend GPSU as a super tool for managing tracks and routes. It will calibrate maps for itself but only save the calibration in its own format. MAPC2MAPC will convert these .gux files; alternatively, MAPC2MAPC will use GPSU's library of datums and calibrate maps directly - useful if you only have a PocketPC or Smartphone system without a desktop system for calibrating maps.

MAPC2MAPC is undergoing intermittent development. If you need a feature, it may be possible to incorporate it.
Email calfiles -at- the-thorns.org.uk