| Radar Gridding Advice Sought [message #61190] |
Wed, 09 July 2008 06:50  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Folks,
An answer by Paolo this morning reminded me I could
use some help on a problem.
I have some radar data in the form of rays of a particular
angle and radius. If I simply plot the rays, I get a pie-shaped
wedge, with lots of white space between rays that increases
as I get further from the point of the wedge. My goal
is to clean this up and have the wedge look more like
an image.
One method I've tried successfully is to create small
polygons for each piece of the wedge and to fill those
polygons with the right color with POLYFILL. This works
a treat, but is slower than I would like.
So, in my free moments (not too many lately!) I have
been thinking about somehow regridding this ray data into
an image-like thing, but I am not sure how to go about
this. With my polygons, the area of each polygon
increases as something like the square of the radius,
so obviously I need to take this into consideration
as I create and populate a "grid".
Does anyone have any experience with this kind of thing?
Any ideas for how you might go about this? I'd be
grateful for any suggestions.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: Radar Gridding Advice Sought [message #61202 is a reply to message #61190] |
Wed, 09 July 2008 09:16  |
Kenneth P. Bowman
Messages: 585
Registered: May 2000
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Senior Member |
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In article <MPG.22de701878b262fd98a3d0@news.frii.com>,
David Fanning <news@dfanning.com> wrote:
> Folks,
>
> An answer by Paolo this morning reminded me I could
> use some help on a problem.
>
> I have some radar data in the form of rays of a particular
> angle and radius. If I simply plot the rays, I get a pie-shaped
> wedge, with lots of white space between rays that increases
> as I get further from the point of the wedge. My goal
> is to clean this up and have the wedge look more like
> an image.
>
> One method I've tried successfully is to create small
> polygons for each piece of the wedge and to fill those
> polygons with the right color with POLYFILL. This works
> a treat, but is slower than I would like.
>
> So, in my free moments (not too many lately!) I have
> been thinking about somehow regridding this ray data into
> an image-like thing, but I am not sure how to go about
> this. With my polygons, the area of each polygon
> increases as something like the square of the radius,
> so obviously I need to take this into consideration
> as I create and populate a "grid".
>
> Does anyone have any experience with this kind of thing?
> Any ideas for how you might go about this? I'd be
> grateful for any suggestions.
>
> Cheers,
>
> David
David,
You should be able to use MAP_IMAGE to do this.
Select the azimuthal equidistant project, which is equivalent to
polar coordinates. You will need to create a set of fake coordinates
for your radar data. Longitude is equivalent to the radar azimuth,
and co-latitude (90 - latitude) is equivalent to radar range.
Ken
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