Hello, one of the libraries used by gvSIG (JTS) has a function called signedArea(). From their doc: "public static double signedArea(Coordinate[] ring) Returns the signed area for a ring. The area is positive if the ring is oriented clockwise." It's not easy to check if this is the cause, because gvSIG changes the orientation when you add a counter-clockwise polygon in editing mode. I understand Wolfgang is using polygons which were not previously edited with gvSIG, so maybe they are originally counter-clockwise? I'm not sure this is a bug. You can get the area with "abs(area())" and the orientation with "area() > 0". Maybe the orientation is useful in some context... Regards, Juan Lucas Domínguez Rubio --- Prodevelop SL, Valencia (España) Tlf.: 96.351.06.12 -- Fax: 96.351.09.68 http://www.prodevelop.es <http://www.prodevelop.es/> ---
________________________________ De: [email protected] en nombre de Wolfgang Qual Enviado el: vie 27/11/2009 14:53 Para: Users and Developers mailing list Asunto: [Gvsig_english] gvSIG 1.9::strange result when calculating area Hi list, I just used the area()-Function to calculate the area of a polygon them and was surprised, as all values were negative. The absolute value was correct, "only" the minus is very strange. The layers I tested were from our official database. I am confused by this, as determinating the area using the measure tool results in the correct value (without "-"). Moreover, if I use the "split"-tool and recalculate the area, the area of the splitted geometries is positive (the rest remains negative). Very strange. Any ideas are appreciated very much. Best, Wolfgang -- <https://correo.prodevelop.es/exchange/jldominguez/Borradores/RE:%20[Gvsig_english]%20gvSIG%201.9::strange%20result%20when%20calculating%20area.EML/1_multipart/logo_b.gif> Wolfgang Qual Referat für Gesundheit und Umwelt Umweltschutz Umweltvorsorge RGU-UW 11 Bayerstraße 28a 80335 München Telefon +49 - 89 - 233 - 4 77 17 Telefax +49 - 89 - 233 - 4 77 05 http://www.muenchen.de/umweltatlas [email protected] Bitte beachten Sie die Hinweise zur elektronischen Kommunikation mit der Landeshauptstadt München: http://www.muenchen.de/ekomm
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