Hello Mark Indeed Sedona is surely a serious candidate. Maybe one aspect to take in consideration, depending how "core" the geospatial services would be, is that Sedona depends on a LGPL library (GeoTools, bundled separately) for map projections, Shapefile and GeoTIFF support. So those features could not be in core since category X dependencies shall be optional.
Regarding referencing by coordinates (including map projections), I'm aware of 3 libraries having a license compatible with Apache: * Apache SIS (Apache License) * PROJ4J (Apache license) * PROJ-JNI (MIT license) PROJ-JNI is a binding to PROJ native library using Java Native Interface (JNI). PROJ is the most well known map projection library, but it is difficult to bundle native code in a Java application. I'm not in a neutral position to said that, but I believe that Apache SIS is the most powerful open source pure-Java referencing library. But it is relatively big, about 4 Mb for the referencing module with its dependencies, not counting the optional EPSG geodetic dataset (because not compatible with Apache license). Apache SIS is not the library with the largest amount of map projections (PROJ4J has more), but it handles some difficult problems and scale well with three- or four-dimensional data (or more). PROJ4J is a lightweight library which may be sufficient if data are mostly two-dimensional (limited 3D support seems also possible) and if uncertainty of a few metres in coordinate transformations (depending how datum shifts are specified) is acceptable. It is possible to write some code in an implementation-independent way using GeoAPI interfaces, which aim to do what JDBC interfaces do for databases. Apache SIS and PROJ-JNI are implementations of GeoAPI interfaces, so by using those interfaces you can let users choose among those two implementations. I think that GeoAPI wrappers could easily be contributed to PROJ4J as well if there is a desire for that. Regarding Geohash, if we are talking about the algorithm described at https://en.wikipedia.org/wiki/Geohash, then SIS already supports it. SIS supports also the Military Grid Reference System (MGRS), which can be seen as another kind of geohash with better characteristics. Regards, Martin --------------------------------------------------------------------- To unsubscribe e-mail: dev-unsubscr...@spark.apache.org
