[Proj] WGS84 to NAD27 Coordinate conversion in Android

[Greg Troxel]

Robb Main <rmain.mws at gmail.com> writes:

> I need to convert WGS84 (lat, long) coordinates from GPS to NAD27 UTM
> Eastings & Northings coordinates, primarily in Canada, in an Android
> environment. To maximize accuracy of the end result, I believe the NTv2
> grid corrections must be applied (though adding 13.5MB to the final
> solution is not desireable).
>
> I've looked at Proj.4 codebase, and I'm not at all sure it's the best tool
> for this purpose. The JNI support for proj.4 appears to be for java support
> under linux/windows/macos. GDAL uses proj.4 & appears to build for android
> ( https://trac.osgeo.org/gdal/wiki/BuildingForAndroid ), so it _IS_
> possible (with some pain), though I'm not sure this is current info.
> Regardless, GDAL is overkill for my needs, as all I need is coordinates.

I realize you are heading down the java path, but:

It's quite possible to use the NDK to compile C code for android.  As an
example, the tmux package, available from

  https://f-droid.org/en/packages/com.termux/

This even includes clang so you can build C code on the phone.

It should be not super hard to add proj as a package within the termux
ecosystem, so you can install it with apt-get.

Another example is OSMAnd, which has some native code, I'm pretty sure
for routing.