gis:project-lat-lon-from-ellipsoid
gis:project-lat-lon-from-ellipsoid latitude longitude ellipsoid-radius ellipsoid-inverse-flattening
Report the position, in NetLogo space, of the given latitude and longitude pair according to the current map projection and transformation and the given ellipsoid parameters.
Like the location-of primitive, the reported xcor and ycor
values are reported in a two-item list of [xcor ycor]
and an empty list if the specified point is outside of
the bounds of the netlogo world.
The two defining parameters of a ellipsoid for
the purposes of this primitive are the radius and the
inverse flattening metric. These parameters can be
easily found by examining either the WKT definition
of a given projection/datum pair or the .prj file for
the desired datum. For example, if you open the .prj file
for a shapefile exported with the WGS66 datum in a text editor,
you will see, somewhere in the file, this bit of text:
DATUM["D_WGS_1966",SPHEROID["NWL_9D",6378145,298.25]].
If you look at the SPHEROID section of that text, the
first number is the radius of that ellipoid and the
second is the inverse flattening.
Once we have these numbers, we can project data that is relative to WGS66 like so:
let location gis:project-lat-lon my-lat my-lon 6378145 298.25For more on earth ellipoids, see: https://en.wikipedia.org/wiki/Earth_ellipsoid