<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi,<div> Thanks to inputs from Mike and Prasanth, I was able to learn the correct procedure to generate the surface normal glyph for a triangle cell! :-) </div><div><br></div><div>The procedure is to first use vtkPolyDataNormals and set ComputeCellNormalsOn and then pass the results to vtkCellCenters to generate the normal at the center of the cell. </div><div><br></div><div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;">vtkPolyDataNormals triangleCellNormals</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"> triangleCellNormals SetInputConnection [triangleCellDataSetSurfaceFilter GetOutputPort]</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"> triangleCellNormals ComputePointNormalsOff</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"> triangleCellNormals ComputeCellNormalsOn</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"> triangleCellNormals SplittingOff</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"> triangleCellNormals FlipNormalsOff</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"> triangleCellNormals ConsistencyOn</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"> triangleCellNormals AutoOrientNormalsOn</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"><br></span></font></div><div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;">vtkCellCenters triangleCellNormalsAtCellCenters</span></font></div><div><font class="Apple-style-span" face="Monaco" size="2"><span class="Apple-style-span" style="font-size: 10px;"> triangleCellNormalsAtCellCenters SetInputConnection [triangleCellNormals GetOutputPort]</span></font></div><div><br></div><div>After that you can pass the normal co-ordinates to vtkGlyph3D for generating the surface normal glyph. </div><div><br></div><div>The full source code is attached with this email.</div><div><br></div><div>Best regards,</div><div><br></div><div>Elvis Dowson</div></div></div><div><br></div><div></div></body></html>