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Mapping questions [message #31177] Thu, 20 June 2002 17:32 Go to next message
nstsmt is currently offline  nstsmt
Messages: 3
Registered: June 2002
Junior Member
Hi,
I am new to IDL, and am hoping someone can point me in the right direction to
accomplish the following 3 tasks. Any advice would be greatly appreciated.

Task 1: Start with a globe and some form of overlay to show land forms. Allow
the user to zoom in on an area, and show more detail in the map.

Task 2: After zooming to a specific area (say Alabama), I have image data that
has a associated pixel map that has the UTM coordinates for each and every
pixel from the image. I would like to plot on the map the location of each
pixel(or really just the outer edge of the image which do to motion is not a
square)

Task 3: I also have some annotations to apply to the map. At a given latitude
and longitude, I want to draw a circle with a radius of 1.0 nautical miles.

Any thoughts on how to accomplish any of this? I looked at the globe demo, and
I understand how that works, but I dont know how to zoom.

Thanks for any help that you could provide.

Neil Talsania
Re: Mapping questions [message #31254 is a reply to message #31177] Wed, 26 June 2002 08:17 Go to previous message
David Fanning is currently offline  David Fanning
Messages: 11724
Registered: August 2001
Senior Member
NSTSMT (nstsmt@aol.com) writes:

> Thanks for the help. I made some progress, using direct graphics, and think
> that I know what I need to do to get the zooming working. For item 2, I dont
> want to actually display the image, but rather put a plot of the area of
> coverage on the map. I think I figured this out also.
>
> For the ellipse, I am still having trouble. I looked at the ellipse program
> that you suggested, and I can not get it to work. I am misunderstanding what
> input to give it. What I tried to do was give it the end points of the major
> axis, and the minor axis, but that didnt seem to work. Any suggestions?

It needs the radius of the ellipse in the two directions. The
code in my program looks like this:

ELLIPSE, lonradius, latradius, 0, 0, 360, $
centerLon, centerLat, Color=black

Here lonradius and latradius is the distance from the
edge of the ellipse to the center, in degrees. There is
0 degree tilt to the ellipse, I'm drawing from 0 to 360 degrees
around the ellipse, and I specify the center lat and lon of the
ellipse in degrees.

Cheers,

David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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