[postgis-users] PostGIS Geography and Rhumb Lines

Sandro Santilli strk at keybit.net
Wed Nov 28 02:33:16 PST 2012

PostGIS-2.1 (in development) has an ST_Segmentize implementation for
"geography" type, which should help with rhumb lines.

You may or may not need to segmentize depending on the operation you
want to do on those lines. Anyway it would be practical to use in your
SQL queries if you don't want to store the segmentization persistently.


On Wed, Nov 28, 2012 at 01:39:09AM -0800, Derek Meyer wrote:
> My current project involves creating a spatial database of world-wide
> airspace data, where each known flight information region is a polygon
> containing boundaries that are a combination of great circle lines,
> rhumb lines, and arcs.
> It seems straight forward enough that these polys could be easily
> inserted into the database via ST_GeographyFromText fed with a WKT
> GEOMETRYCOLLECTION of these compound boundary types, but I'm wondering
> about how to deal with rhumb lines in such a case since the Geography
> functions, if I understand correctly, base everything around a round
> earth model and utilize great-circle by nature.
> Is there any way to explicitly declare a rhumb line in an insert query
> such as this?  I've seen some examples elsewhere where a temporary
> projection to 2D is utilized and then segmentized to
> render/interpolate coordinates for a linestring that would more
> accurately represent said rhumb line.  Is this still the accepted
> approach?  Practical?  If so, how would such an approach be
> implemented in context of the SQL query?
> Any info/suggestions welcome and appreciated.
> Thank you for your time,

More information about the postgis-users mailing list