Re: Lat/Lon to Polar: Revisited

• To: Kevin Manross <kevin.manross@xxxxxxxx>
• Subject: Re: Lat/Lon to Polar: Revisited
• From: Bill Hibbard <billh@xxxxxxxxxxxxx>
• Date: Mon, 24 Oct 2005 09:32:45 -0500 (CDT)

Hi Kevin,

> >But one useful piece of information is "(516,0)". Note that
> >516 is about half of LengthX = 1033, so the offending grid
> >box is at the haflway point along X. In fact, the offending
> >grid box from X=516 to X=517 exactly straddles 1033/2.
> >
> >If X is your azimuth coordinate, is there an error in
> >computing angles halfway around the circle? One possibility
> >is that angles increase from X=0 to X=516, then there is a
> >decrease from X=516 to X=517, then they increase again.
> >Something like that. Or if X is your radius coordinate, is
> >there a similar error in computing radius halfway out, at
> >X=516?
>
> Yes, in my original terrain file, the domain is a LinearLatLon set with
> X -> Lon, and Y -> Lat.  If you put the radar at the center of that
> domain, and my X (Lon) increases for X = 0->1033, then my azimuth will
> decrease to 0 (at the midpoint of X [516]) and then increase.

Azimuth is an angle (essentially the same as longitude according to
my understanding) so I would expect it to either increase or decrease
consistently around the circle, rather than do some of both.

Good luck,
Bill

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