[R-sig-Geo] smoothing contours (image.smooth)

[Roger Bivand]

On Thu, 24 Apr 2008, F. De Sales wrote:

>
>    Hi all,
>    I was wondering if anyone in here is familiar with
> the command "image.smooth".
>    How can set the arguments dx, dy and theta to
> minimize the smoothing?

Read ?image.smooth in the fields package, and run the examples with 
various values until you can see what they do, with the alternative of 
reading the source code.

>    Is there any other way to get smoother contour
> maps, ie, without so many sharp corners?

The function is not adding any information, so if there are sharp corners 
in the contours, then there are sharp corners in the data, and smoothing 
is not your friend. One possibility is to change the resolution of the 
image, which should remove sharp boundaries that are only artefacts of the 
resolution - for example by interpolating to a denser grid.

Roger

>    I'd appreciate any help.
>    Thank you very much.
>
>
>
>
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no