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Re: cgmap_gshhs.pro minarea issue [message #86613 is a reply to message #86609] Fri, 22 November 2013 08:50 Go to previous messageGo to previous message
David Fanning is currently offline  David Fanning
Messages: 11724
Registered: August 2001
Senior Member
Takis.Velissariou@deep-c.org writes:

> 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)

I still don't know what to make of this. The documentation is screwy.

At one place in the header file you find this:

"area magnitude scale p (as in 10^p) = flag >> 26.
We divide area by 10^p."

Then, in the next couple of lines, you find this *twice*:

"Area of polygon in km^2 * 10^p for this resolution file"

We need to know the area of known polygons to be able to tell.

David



--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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