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Re: cgmap_gshhs.pro minarea issue [message #86609 is a reply to message #86594] Fri, 22 November 2013 07:57 Go to previous messageGo to previous message
Takis.Velissariou is currently offline  Takis.Velissariou
Messages: 1
Registered: November 2013
Junior Member
On Thursday, November 21, 2013 7:09:28 PM UTC-5, pvelis...@fsu.edu wrote:
> Apparently, in the recent versions (>= 2.2) of gshhs database
>
> the units of the header.area changed from 1/10 km^2 to 1/10 m^2.
>
> For cgmap_gshhs to work properly the line:
>
> polygonArea = header.area * 0.1 (ok for gshhs < 2.2)
>
> should be changed to:
>
> polygonArea = header.area * 1.0e-7 (for gshhs >= 2.2)

David,

I saw the modified code in gmap_gshhs.pro and I think that:
magnitude = ISHFT(f, -26) AND 1B
should change to:
magnitude = ISHFT(f, -26) AND 255B

also
polygonArea = header.area * 0.1 * 10^magnitude
should change to:
polygonArea = header.area * 0.1 (for version lt 9)
and
polygonArea = header.area * 10^(-magnitude) (for version gt 9)

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