Re: Courses in IOF XML Format

Posted by Peter Effeney on
URL: http://maprun.308.s1.nabble.com/Courses-in-IOF-XML-Format-tp19p37.html

Here is my understanding of coordinate systems ... a complex area, and someone else might be able to add to this discussion.

MapRun is based on the "Internet" mapping system of Google/Microsoft etc.

Locations are expressed simply as Latitude and Longitudes without reference to any specific coordinate reference system.

If you look into a KMZ file (Map) or a KML file (Course) or a GPX file (Track) you will simply see Lats and Lngs. (To look at a KMZ file you need to use one the usual unZIP tools to un-zip it).

"Internet Maps" use a Mercator projection based on the World Geodetic System (WGS) 1984 geographic coordinate system (datum).
 
If you are doing conversions in a Geographic Information Systems (GIS), like QGIS, then the system you need to convert to is: EPSG:4326 or "Google Mercator"

GPS systems in Android and Apple phones provide the users location in Latitude and Longitude.  Garmin GPS's and GPS watches all use Latitude and Longitude.

IOF XML version 2.0.3 exports control locations as:
- x/y coordinates on the map used to set the course, and
- if the map is Geo-referenced and you are using a version of OCAD that supports geo-referencing (or other system), it also includes coordinates in whatever coordinate system you have set in OCAD.

Sample contents of files are provided at: http://maprunners.weebly.com/uploads/6/8/6/6/6866500/technical_overview_-_extract_-_file_formats_v1.pdf

IOF XML version 3 exports control locations in Lat/Lng.

Converting IOF XML to KML

You can export a course in IOF XML v2.0.3 and use O-utils to convert the control locations to Lat/Lng in a set of KML files (one course per file), provided that:
- the IOF XML file has coordinates in it (see above), and
- the coordinate system is UTM / WGS 84

Otherwise, if the IOF XML v2.0.3 file only has control locations x,y coordinates on the map, AND, you have a KMZ version of that map (with exactly the same dimensions), then there is another function at O-utils to use the combination of the KMZ file and the IOF XML file to determine the Lat/Lng of the controls.

Otherwise, some versions of OCAD can export a KML file directly, or can export a GPX file which can be opened in Google Earth and then saved as a KML file.

In conclusion, if you have location data in a KMZ (map), KML (course), GPX (track), the locations will be in Lat/Lng, they will apply anywhere on Earth, and will have no explicit coordinate system specified (there are no options).

Peter