I'm using PROJ.4 in my work and now I want to know how it convert coordinate well, especially longitude/latitude <-> UTM.
I can compare the result from proj command with values from some websites which provide coordinate conversion, but I don't think I can convince my clients or my supervisors with such unofficial data.
Is there any official or authorized reference to test coordinate conversion?
Proj.4 itself has a large test suite.
The US military-based agency, National Geo-information Agency (NGA) has a "Gold Data" set that they use to certify their GEOTRANS software. As UTM was originally defined by the US military, that should be considered official.
The oil & gas industry released a test suite, Geospatial Integrity of Geoscience Software that also covers Universal Transverse Mercator. Those tests are based on entries from the EPSG Geodetic Parameter Registry
Disclosure: I'm on the subcommittee that maintains the EPSG registry.
