Essentially, I would like to define the origin of a projected coordinate system to be A WGS84 lat long coordinate I pass in. Unfortunately standard UTM zones aren't accurate enough so I need to set the origin using the current lat/lon location at startup then do conversions using that.

It looks like latlon.h and tmerc.h are what I want, how would I specify the lat/lon I want for the origin? Or is this perhaps not part of the embedded functionality?

I've been looking at the examples, and it appears the conversions are mostly for lat-lon rather than lat-lon-altitude. Is it possible to handle points with altitude? If not, it looks like altitude conversions can be done with a simple offset when converting meters to meters, is that accurate?

Also, would these conversion extensions be safe to use? I noticed the following comment in one of the examples:

// BSG 28-10-2010

// TODO: clear up this test

// it is more a test than an example

// the results are sometimes WRONG

Thank you for all of your help with this.

Cheers!

Andrew Hundt