CGMAP__DEFINE
Provides an easy way to set up a map projection coordinate space using GCTP map
projections normally accessed via Map_Proj_Init. Allows an unlimited number of map
overlays, and can provide a fresh map structure on demand, eliminating the problem
of ephemerial map structures that plaqued Map_Proj_Init until IDL 8.x. This program
is basically a wrapper for Map_Proj_Init, with additional features that make it
superiour for working with map projections in IDL.
Categories
Graphics, Map Projections
:File_comments:
Only GCTP projections are allowed. If you wish to use projections normally
set up with Map_Set, use the comparable cgMap_Set command.
Author
FANNING SOFTWARE CONSULTING::
David W. Fanning
1645 Sheely Drive
Fort Collins, CO 80526 USA
Phone: 970-221-0438
E-mail: david@idlcoyote.com
Coyote's Guide to IDL Programming: http://www.idlcoyote.com
History
Change History::
Brought over to the Coyote Library from a similar routine in the Catalyst Library.
Updated to account for the bug that creates incorrect result in UTM projections
when using the WGS84 ellipsoid. The Wallbeck ellipsoid is substituted for the
WGS84 ellipsoid in this instance. David W. Fanning, 7 November 2011.
Added IS_CYLINDRICAL method to solve a problem with grid labeling and drawing
of grid lines. 16 Dec 2011. DWF.
Added ERASE method to erase the display. 28 Dec 2011. DWF.
Added check for identical range values in FORWARD method. 30 Dec 2011. DWF.
I am convinced that the map structure returned by Map_Proj_Init, when there
is a LIMIT used in the call contains a uv_box with incorrect latitude values.
This is important because other routines (e.g., cgMapGrid) depend on these values.
I've created a fix wherein, I fixed the uv_box latitude values to correspond
to the LIMIT of the map projection. 6 April 2012. DWF.
Set the default CENTER_LATITUDE and CENTER_LONGITUDE to 0.0. 9 April 2012. DWF.
Added NOFORWARDFIX keyword to allow skipping of the "fix" in the FORWRD method,
as sometimes this is not needed or required. 29 June 2012. DWF.
Copyright
Copyright (c) 2011-2012, Fanning Software Consulting, Inc.