| Mapping Functionality in IDL 8.1 [message #75735] |
Tue, 12 April 2011 16:40 |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
Folks,
I promised to report back from the IDL User Group
meeting about the new mapping functionality coming
in IDL 8.1 (due out in the morning, as I heard it
today at the meeting).
I'm afraid I don't have much to report. The big
news is the Map function can now draw a map whose
boundaries cross the international date line. (An
outstanding bug in the iTool map object since IDL
6.3, when the Map object was introduced.)
The other big mapping news is that that Map object
can now use the GSHHS database (when the HIRES keyword
is set) in the MapContinents routine. This is a
functionality I have been using since 2006 when
I wrote Map_GSHHS_Shoreline to draw all my shorelines,
and I highly recommend it.
http://www.idlcoyote.com/map_tips/gshhs.html
I wasn't able to determine if it is the implementation
of the GSHHS data base that is slow, or if it is the map
object that is slow, but we waited quite a long time
after the command was typed to see the result. I've
never experienced a delay like that with my implementation
of GSHHS, so I don't know what to think. I am guessing
they always use the full resolution of the GSHHS database,
which is almost always unnecessary in practice and does
take a LONG time to draw. (My routine allows you to choose
the resolution of the GSHHS database you want to use.)
The biggest problem I see with the Map function is that
ITTVIS continues to insist that people want to warp an
image onto a map projection. I've spent a number
of years working professionally with people who did map
projections for a living, and I have never once known
anyone who wanted to do this. Everyone I know HAS an
image (which they emphatically do NOT want to warp!),
and they want to fit a map projection onto that.
I'm told to expect more "communication" between the
ENVI side of ITTVIS and the IDL side. Here is one case
where listening to the folks who are working with ENVI
could pay immediate dividends. As it is now, the Map
function in IDL appears to me to be more toy than tool.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thue. ("Perhaps thos speakest truth.")
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
