I have computed a digital terrain model from a set of points (x, y, z) using the function interp() in package akima. I want to predict flooded surfaces given target values of z. I can display the flooded surfaces with contour() or image(), but I don't know how to get the polygons delimiting the surfaces. Did anyone write a function for this purpose ?
Many thanks to Roger Bivand, Paul Murrel, Deepayan Sarkar, Barry Rowlingson and Thomas W Blackwell for their replies and their help. Paul Murrel provided me with a function "clines", kindly ported to Windows by Duncan Murdoch. This function does exactly what I need, i.e. it returns a list of polygons corresponding to target value(s) of z.
I wrote a function to compute (hopefully !) what I want, i.e. predicted flooded surfaces given target values of z (managing the cases of several independent watered surfaces, possibly with islands). Provided that Paul Murrel agrees to share his function, I will be happy to send it to anyone wishing to use and improve it (and debug it ;-) ).
Best regards and thanks again,
Renaud
-- Dr Renaud Lancelot, v�t�rinaire CIRAD, D�partement Elevage et M�decine V�t�rinaire (CIRAD-Emvt) Programme Productions Animales http://www.cirad.fr/fr/pg_recherche/page.php?id=14
ISRA-LNERV tel +221 832 49 02 BP 2057 Dakar-Hann fax +221 821 18 79 (CIRAD) Senegal e-mail [EMAIL PROTECTED]
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