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From Ted Dunning <ted.dunn...@gmail.com>
Subject Re: Will it go 'round in circles?
Date Fri, 07 Aug 2015 18:47:42 GMT
On Fri, Aug 7, 2015 at 3:23 AM, Chris Hillery <chillery@hillery.land> wrote:

> I've noticed that several geospatial serialization formats (at least
> "well-known text" and GeoJSON) omit "circle" from their list of basic
> geometric forms, even when they have numerous more complex types such as
> multi-curves. This led me to here:
> http://forums.mysql.com/read.php?23,148162,152625#msg-152625
>
> which offers a reasonably compelling argument for why "circle" is not a
> reasonable shape to discuss in geospatial contexts (loosely, because
> there's no consistent way to map that to a spherical coordinate system).
>

Actually, that argument is super-weak.  It also implies that you shouldn't
have lines (they aren't straight after projection) or squares (they aren't
square after projection). But lines and squares both before and after
projection are very handy.

Circles are useful in many contexts. Drawing the visible horizon for a
particular observer is a great example.  The flight range of an airplane is
another case.  Positional error bounds with Gaussian errors is another.

Yes. You can approximate it using splines or polygons.  But you can
approximate anything that way.

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