Suppose you have an arbitrary GeoJSON file, and the publisher didn't give much supporting documentation – or perhaps it's been provided by a third party who don't know much about it.
Is there a standard way to identify what CRS or SRS the file is in? For example, is there a readily available tool (like a web tool) that can read such a file and identify this?
I'm writing some documentation for a process that is to be used for preparing spatial boundary data files for a process, for converting files from arbitrary publishers into accepted formats, and I'd like a step that users (who usually won't have much specific GIS experience) can follow to see if they need to convert their file's CRS/SRS and if so, what from.
I've seen Identifying Coordinate System of Shapefile when Unknown? but that seems to be exclusive to Shape files.
Best Answer
Assuming your data provider sticks to the format specification, the CRS is in geographic coordinates with WGS84 datum, unless specified otherwise. See also section 3 of the GeoJSON specification.
If your data comes with an unspecified CRS, I know of no other method than having to guess. If the people working with this data know where they should be located, a first educated guess would be a CRS used by the government or military of that area, an information that can be obtained easily for pretty much every region.
Also, you should definitely have a word with your data provider then.