<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">You need to triangulate your polygon. Your data is just a bunch of points ordered counter-clockwise. You can try the vtkDelauney2D filter to try and triangulate the 3 polygons. If that doesn't work (and don't be surprised if it does not) there you may have to do looking elsewhere for triangulation routines. There is a decent one from the "Quake" project from CMU. I have used this successfully many times but the code is really old and takes some adaptation to get working with VTK. Report back on you progress.<DIV> Can you send your data set to the list? or me directly. I may be able to triangulate it for you if that is all you need.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Bitstream Vera Sans; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">-- </DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Mike Jackson Senior Research Engineer</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Innovative Management & Technology Services</DIV><BR class="Apple-interchange-newline"></SPAN> </DIV><BR><DIV><DIV>On Sep 30, 2007, at 6:10 PM, Janny Dong wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite">Hi Eugene,<BR><BR>Thanks for your reply. The data I am using are more than 1000 points (latitudes and longitudes), 3 polygons. The polygons are ordered counter-clockwise. I put them into a .vtk file and read it from my code. The main part of my code to do this is as follows. <BR><BR>//Read the vtk data file.<BR>vtkPolyDataReader *usa = vtkPolyDataReader::New();<BR>usa->SetFileName("greatlakes.vtk");<BR><BR>//clean polydata<BR>vtkCleanPolyData *cleaner = vtkCleanPolyData::New();<BR> cleaner->SetInputConnection(usa->GetOutputPort());<BR> cleaner->SetTolerance(0.005);<BR> <BR>//apply triangle filter<BR> vtkTriangleFilter *triangle = vtkTriangleFilter::New();<BR> triangle->SetInputConnection(cleaner->GetOutputPort()); <BR><BR>//map to polydata mapper<BR> vtkSmartPointer<vtkPolyDataMapper> polyMapper = vtkSmartPointer<vtkPolyDataMapper>::New();<BR> polyMapper->SetInputConnection(triangle->GetOutputPort());<BR> <BR>I am guessing the polygon is not convex. Is there anything I can do to draw the polygons properly?<BR><BR>Janny<BR><BR> <BR><BR><DIV><SPAN class="gmail_quote">On 9/30/07, <B class="gmail_sendername">Eugene Dorfman</B> <<A href="mailto:justadreamer2007@gmail.com">justadreamer2007@gmail.com</A>> wrote:</SPAN><BLOCKQUOTE class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Please attach some code dealing with your polygons - how are you trying to draw them. Seems that the order of the points is either incorrect when specifying them to the vtkPolyData - or you are using the triangulation strip. All you need to do is to load a polygon into a cellarray - and define it as a single cell - than pass it to vtkPolyData. It also might be that the polygon shape is not convex - that is why. Some code would be helpful. </BLOCKQUOTE></DIV><BR><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">This is the private VTK discussion list.<SPAN class="Apple-converted-space"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Please keep messages on-topic. Check the FAQ at: <A href="http://www.vtk.org/Wiki/VTK_FAQ">http://www.vtk.org/Wiki/VTK_FAQ</A></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Follow this link to subscribe/unsubscribe:</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="http://www.vtk.org/mailman/listinfo/vtkusers">http://www.vtk.org/mailman/listinfo/vtkusers</A></DIV> </BLOCKQUOTE></DIV><BR></DIV></BODY></HTML>