Re: [OpenMap Users] CADRG progjection skews around scale 1:50000

Diane,

The "Squished/skewed" appearance you describe is an artifact of
rendering the surface of a sphere (the Earth) onto a plane (the map)
using different projection methods.

Perform a search for "map projections" and you will find plenty of
sites that will explain map projections.

Cheers,
David

On Sep 9, 2008, at 8:06 AM, <dianefitch@comcast.net> <dianefitch@comcast.net
> wrote:

> Don,
>
> Has anyone encountered this problem.
>
> Using Openmap 4.6.3 or 4.6.4 application without any modifications,
> when zooming in or out using CADRG projection, the image is skewed
> around 1:5,149,249 scale and 1:7,000,000 once zoomed in closer tha
> 1:5,000,000 the problem does not appear
>
> I drew a simple range ring about 1degree or lat and 1 degree of lon
>
> It is circular most of the time, but at certain scales it appears
> "Squished"./skewed
> The skewing seems to appear when the graticule lines form a square
> (lat/longs equadistance??) Other scales the latitude
> is wider than the longitude.
>
> This problem does not appear to happen in the Mercator Projection,
> Orthogonal, Gnomonic
> The LLXY projection the range rings are always skewed
>
>
> Example pictures are around 38N Lat and 76W Lon
>
>
> Thanks,
>
> Diane Fitch
> Praxis Engineering
> <skewedRangeRing.bmp><CorrectRangeRing.bmp>

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