When working with remote sensing (RS) and GIS data you will sooner or later face the problem that you need to convert the coordinates of your project to a different coordinate system (to reproject your data).
Unfortunately, especially in ArcGIS, not all coordinate systems and its conversions are provided. QGIS and many other freeware and FOSS GIS, using the GDAL library, tend to be supportive for more reference systems.
The first address when requiring coordinate conversion (reprojection) parameters is probably the epsg website and the corresponding database.
Beside the Microsoft Access database on the EPSG website there is a number of websites available providing online coordinate conversions. Provided a working Internet connection and the requirement of only convert a small number of e.g. GPS points this might be the better way to go.
The online coordinate converter usually tend to convert in/from geographical coordinates (latitude/ longitude in degree) to/from UTM or a national grid.
Some examples for online coordinate converter are:
- The EPSG Geodetic Parameter Dataset (http://www.epsg-registry.org/) is a structured dataset of Coordinate Reference Systems and Coordinate Transformations, accessible through this data registry. The geographic coverage of the data is worldwide, but it is stressed that the dataset does not and cannot record all possible geodetic parameters in use around the world. The EPSG Geodetic Parameter Dataset is maintained by the Geodesy Subcommittee of OGP.
- Degrees, Minutes, Seconds and Decimal Degrees Latitude/Longitude Conversions: http://transition.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html
- UTM <> Latitude/Longitude Converter:
- Spatial reference in a number of formats: http://spatialreference.org/
The nice feature (biggest advantage of this website) is the possibility to download projection files e.g. for ESRI ArcGIS when they are not in your system and you do not want/ know how to incloude it by yourself.
- Country specific e.g. for the UK (OSGB36):
– Ordnance Survey Grid Reference to latitude and longitude
– Latitude/longitude OSGB converter
Software-wise, e.g. when the coordinates exist in any kind of text form or on a GPS, it is worth to look at the Shareware GPS Utility. For a small number of points the free version is sufficient, for more data points or longer tracks it is worth to purchase the software.
The matlab toolbox ConvertCoordinates from Deltares can be used for coordinate transformations between a lot of coordinate systems. There is also a stand-alone version of this program with a Graphical User Interface (GUI) which is called SuperTrans. The basis of this system is the EPSG Geodetic Parameter Dataset, which contains a lot of coordinate system definitions.
“SuperTrans is a MatLab based computer program that can convert coordinates from one coordinate system to another. The basis of this system is the EPSG Geodetic Parameter Dataset, which contains a lot of coordinate system definitions.
The program is capable of the following:
- convert between geographic (lat/lon) coordinate systems;
- convert between projected coordinate systems;
- convert between projected and geographic coordinate systems;
- conversion of single coordinates (*.ldb, *.pol, *.xyz, *.grd)
- conversion of files.”