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Understanding projections

Koordinates enables users to export data in a range of different projections.

A projection describes the specific process by which an area on Earth, which is a sphere, is transformed to a flat, two-dimensional map. This process of transformation unavoidably leads to some form of distortion, but different kinds of projections allow users to decide what is and is not distorted.

How does Koordinates handle projections?

When data is downloaded from Koordinates, it is ‘reprojected’ into the map projection chosen by the user. If the original map projection is chosen, then no re-projection is performed. 

Projections for satellite and aerial imagery

Satellite and aerial imagery is delivered as images or image tiles. The source images are generally supplied in a projection that minimises distortion over the captured area. This is important, as it preserves the resolution of the source images and to reduce subsequent errors introduced through re-projection.

Which projection does Koordinates use?

Koordinates stores all data in its original map projection, as provided by the data publisher. Data is previewed within Koordinates using the Spherical Mercator projection used by Google Maps and other online mapping systems. Note that the stored data is not transformed into Spherical Mercator.

Which projection should I choose?

Koordinates supports most map projections listed in the EPSG database, so it is up to you which projection you choose. If you are unsure of which projection to use, you should maintain the projection in which the data was uploaded. This will be the default projection made available on the download pop-up, and will ensure that your data does not appear distorted.

What is EPSG? 

Koordinates uses the international EPSG system, which provides a unique number to each projection in its database. EPSG numbers should be recognised by most GIS applications. 

Koordinates updates from the EPSG database at least once per year. If your EPSG is not supported, please get in touch. 

I'm a data publisher. Do I need to provide an EPSG?

All geospatial data on the Koordinates platform is georeferenced according to an EPSG number. Most of the time, the platform should be able to automatically detect projection information. However, for file formats that do not support projection information, publishers need to provide an EPSG. 

Non-georeferenced JPEG or TIFF imagery will be treated as a 'document.'