## July 15th 2014, Geo-Spatial Coordinate Systems

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For geo-spatial applications geographic coordinates are handy. But geographic coordinates are **not** the most efficient coordinate space for representing geo-spatial objects.

Ideally, a domain space needs to fulfill the following conditions:

- should allow precise location (sub-cm resolution)
- should represent space uniformly (e.g. no deformation at poles)
- should be global to allow coordinate mappings from and to other coordinate systems
- should support geometric manipulations efficiently
- should be metric to allow distance calculations efficiently
- should be easily to interpret by users
- should allow compact storage

While the above conditions clearly cannot be met all together, for sake of efficiency the so called ECEF coordinate system is the best choice in my personal long-term experience.

ECEF is an euclidian (metric) 3D coordinate system where the three x-, y- and z- axis are attached to the earth as shown below:

ECEF is a global, efficient, metric coordinate system. It is not intuitive and does not offer the most compact representation, but it is best for internal computations.

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