[Gdal-dev] projected bounding box
ed at topozone.com
Mon Jul 14 13:03:57 EDT 2003
Sorry - your first message made it sound like a specific application. If you're building a general-purpose tool, you need to solve the general case <g>. If you need to handle arbitrary map scales and projections, I can't think of way to select a good buffer value automatically (or at least, not a way that would be easier than projecting along the entire line).
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA 01863
ed at topozone.com
From: Jonathan Coles [mailto:jonathan at intevation.de]
Sent: Monday, July 14, 2003 12:52 PM
To: gdal-dev at remotesensing.org
Subject: RE: [Gdal-dev] projected bounding box
On Mon, 2003-07-14 at 18:39, Ed McNierney wrote:
> This is a tricky problem to solve in a general case,
> and has been the source of a number of software bugs
> I've met along the way!
Hopefully, in the future, not with Thuban ;)
> To do it right, you need to take EACH POINT along
> each of the edges of the output bounding box (rectangle)
> and reproject it back into the source projection. For
> each edge you calculate the appropriate minimum/maximum
> value in the input projection.
I was afraid of this response.
> it might be easier for you to take your specific application and calculate
> a "buffer" value.
> This is obviously a special-case solution, but it's
> probably a lot simpler and faster than trying to solve
> the general problem.
That's the problem, this isn't a special case situation. It should
really work with any projection anywhere on the globe. It certainly is
something for me to think about though. Perhaps I can come up with a way
that will guarantee a good buffer value. Thanks for your thoughts.
Jonathan Coles jonathan at intevation.de
Intevation GmbH http://www.intevation.de
More information about the Gdal-dev