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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT face="Times New Roman">vtkCurvature calculates the mean or gauss curvature of a surface. However the interpretation what one would consider a considerable curvature (been not flat) may depend on the size of the surface considered. For example taking a 5 mm area of a 10 cm sphere would be flat in average, in contrast to a 2 cm big area which will be convex. <SPAN style="mso-spacerun: yes"> </SPAN>Currently I use the following approach. At each point of the surface I clip the surface around that point of the diameter which I am interested in. Than I measure the angle between the surface normal at the centre and the surface normals at the other points of the clipped portion of the surface. Finally the mean angle is calculated, representing the deviation from been flat. A mean angle of 0 would mean the surface is flat. Unfortunately this approach does not differentiate between concave and convex and mixed surfaces. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT face="Times New Roman">Are there already established algorithms measuring the curvature in respect to the size of the surface investigated?<o:p></o:p></FONT></SPAN></P>
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-GB style="mso-ansi-language: EN-GB"><FONT face="Times New Roman">Regards, Peter. <o:p></o:p></FONT></SPAN></P></FONT></DIV>
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<DIV><FONT face=Arial color=#000000 size=2>------------------------------------</FONT></DIV>
<DIV><FONT face=Arial color=#000000 size=2>Peter Böttcher, Dr med vet, DipECVS</FONT></DIV>
<DIV><FONT face=Arial color=#000000 size=2><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">European Veterinary Specialist in Surgery</SPAN></FONT></FONT></DIV>
<DIV><FONT face=Arial color=#000000 size=2><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Fachtierarzt für Kleintierchirurgie</SPAN></FONT></FONT></DIV>
<DIV><FONT face=Arial color=#000000 size=2><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT></FONT><FONT face=Arial><FONT size=2>Klinik für Kleintiere</FONT> <BR><FONT size=2>Universität Leipzig</FONT> <BR><FONT size=2>An den Tierkliniken 23</FONT> <BR><FONT size=2>D-04103 Leipzig (Germany)</FONT></FONT></DIV>
<DIV><FONT face=Arial><FONT size=2>Tel: +49-341-9738700</FONT> <BR><FONT size=2>Fax: +49-341-9738799</FONT></FONT></DIV>
<DIV><FONT face=Arial><FONT size=2>email: <A href="mailto:boettcher@kleintierklinik.uni-leipzig.de">boettcher@kleintierklinik.uni-leipzig.de</A></FONT><BR></FONT></DIV></DIV></BODY></HTML>