[postgis-users] drawing nautical data on projection 4326[solution?]

Dave dave.potts at pinan.co.uk
Fri Apr 29 01:05:03 PDT 2011


I think I have a solution to this issue

I am going to convert my point origin to meter based projection (eg 
google 900913), create my line data, then transform it back to the 4326 
projection,  in this way the scale factors calculations should be done 
by the proj library.

Does this sound like a decent solution?

On 28/04/2011 10:48, Dave wrote:
> I have some line  data measured in nautical miles.
>
> I want to draw these points on a map using the 4326 projection, the 
> srs entry for this projection gives the unit of measurement as degree.
>
> A nautical mile is one minture of an arc of lattitude ie 0-60, the 
> projection is measured in 0-100.
>
> So does this mean that when I want to draw a line measured in nautical 
> miles,  I have map 0-60 on to 0-100 grid , ie I have to apply  0.6 
> factor ?
>
> So a line  starting at lat 1.2 and ending at  lat 2.7 becomes a line 
> 1.12  to  2.42 ?
>
> regards
>
>
> Dave.
>
>
>
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