| 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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