Take the 2-minute tour ×  On my previous question, it was
advised I convert lat/lon/altitude to spherical or Cartesian
coordinates. I'm not working near the poles and it would be safe
to assume a spherical earth. What would be the best way to go
about this with the minimal amount of operations? Would it be
best to use x/y/z or phi/theta/rho? I'm working on a small
microcontroller, with no hardware FPU (software FPU only!) so
every cycle counts.  share|improve this question Using a
spherical model introduces huge errors in the Cartesian
coordinates (relative to the range of topographic elevations on
the earth), because the ellipsoid has about a 23 km vertical
deviation from the spheroid in places. Make sure your
application can tolerate such errors. –  whuber Dec 4 '10 at
19:01 @whuber: These errors are tolerable. –  Thomas O Dec 4 '10
at 19:14 add comment  1 Answer  Note that "Lat/Lon/Alt" is just
another name for spherical coordinates, and phi/theta/rho are
just another name for latitude, longitude, and alti