<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">Hi, I'm pretty new to VTK, and my book hasn't arrived yet, however I'm under a bit of pressure to get this task finished, so any help is really appreciated....<DIV><BR class="khtml-block-placeholder"></DIV><DIV>I have some weather data such as air temperature for a number of points across a country (so it's an unstructured grid), this data is retrieved from a database by my application (which is an OS X Cocoa app, using Obj-C/++). For each point I have a northing, easting and elevation, so x,y,z. I'm trying to plot some sort of isosurface, I've written some code which I think puts my data into a vtkUnstructuredGrid, which is pasted below.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">- (vtkDataSet *)samplesAsVTKDataSet {</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">vtkPoints</SPAN></FONT><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">*newPts</SPAN></FONT><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">= vtkPoints::New();</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">vtkDoubleArray</SPAN></FONT><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">*newScalars = vtkDoubleArray::New();</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">PointValue</SPAN></FONT><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">*point; // this is a class representing a value associated with a coordinate</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" color="#760F50" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">double</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> xyz[</SPAN></FONT><FONT class="Apple-style-span" color="#0000FF" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">2</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">];</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" color="#760F50" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">int</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> i, length = [samples count]; </SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" color="#760F50" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">for</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">(i=</SPAN></FONT><FONT class="Apple-style-span" color="#0000FF" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">0</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">; i<length; i++) {</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">point = [samples objectAtIndex:i];</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">xyz[</SPAN></FONT><FONT class="Apple-style-span" color="#0000FF" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">0</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">] = [[point north] doubleValue];</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">xyz[</SPAN></FONT><FONT class="Apple-style-span" color="#0000FF" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">1</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">] = [[point east] doubleValue];</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">xyz[</SPAN></FONT><FONT class="Apple-style-span" color="#0000FF" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">2</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">] = [[point elev] doubleValue];</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">newPts->InsertPoint(i,xyz);</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">newScalars->InsertValue(i, [[point value] doubleValue]);</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">}</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">vtkUnstructuredGrid</SPAN></FONT><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">*dataSet = vtkUnstructuredGrid::New();</SPAN></FONT><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">dataSet->SetPoints(newPts);</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">dataSet->GetPointData()->SetScalars(newScalars);</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; min-height: 14px; "><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">newPts->Delete();</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">newScalars->Delete();</SPAN></FONT><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN><FONT class="Apple-style-span" color="#760F50" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">return</SPAN></FONT><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;"> dataSet;</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" face="Monaco" size="2"><SPAN class="Apple-style-span" style="font-size: 10px;">}</SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Now, I'm a little stuck, I think I need to create a vtkDataSetMapper, or maybe some sort of Filter - as I'm guessing somewhere in the pipeline I've got to define how vtk should interpolate between the points?</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Anyway, if someone can point in the right direction that would be great.</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Cheers</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Dan</DIV></BODY></HTML>