[Gdal-dev] Tool to convert shapefile from [-180, 180] to [0, 360] range

Curt, WE7U archer at eskimo.com
Thu Jun 15 11:02:43 EDT 2006


On Thu, 15 Jun 2006, Charles Wivell wrote:

> The shift you should use if you want the values between -180 and
> 180 for values less than -180 would be:

I'm not interested in the conversions in this case as they're
trivial.

Are apps normally designed to handle 0-360 or are files expected to
conform to -180 to +180?  I have two types of files now that don't
correspond to -180 to +180.  I understand that for other planets it
is common to do the 0-360 thing.

Also these questions:

> *) What should an application do with a shapefile that contains
> polygons with longitudes in the -189.9 to -180.0 range?  Is there an
> easy way to split up the shapes so they don't fall off the edge of
> the earth?

Note:  Our app uses unprojected lat/long in WGS84 only for display.
-180 is the left edge, +180 is the right edge (if zoomed out far
enough to see them both).  Drawing polygons or lines that cross the
180 boundary is a big hassle, we'd have to split them before
drawing.

--
Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"



More information about the Gdal-dev mailing list