<div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small">Hi Benedikt,</div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small">if you are asking about which mesh smoothing algorithm is used, I think this source code file answers that:</div><div class="gmail_default"><font face="verdana, sans-serif"><a href="https://sourceforge.net/p/itk-snap/src/ci/master/tree/Logic/Mesh/VTKMeshPipeline.cxx#l167" target="_blank">https://sourceforge.net/p/itk-<wbr>snap/src/ci/master/tree/Logic/<wbr>Mesh/VTKMeshPipeline.cxx#l167</a></font><br></div><div class="gmail_default"><br></div><div class="gmail_default">Its <a href="https://sourceforge.net/p/itk-snap/src/ci/master/tree/Logic/Mesh/VTKMeshPipeline.h#l122" target="_blank">declaration</a> says it is an <a href="http://www.vtk.org/doc/nightly/html/classvtkImageGaussianSmooth.html" target="_blank">vtkImageGaussianSmooth</a>. If documentation is not enough, you can find <a href="https://gitlab.kitware.com/vtk/vtk/blob/master/Imaging/General/vtkImageGaussianSmooth.cxx" target="_blank">its source code</a> in VTK.</div><div class="gmail_default"><br></div><div class="gmail_default">As the sigma is passed into there as a parameter, I believe the user-modifiable preferences in the program control it.</div><div class="gmail_default"><br></div><div class="gmail_default">Paul (CC'd) might have more explanations.</div><div class="gmail_default"><br></div><div class="gmail_default"><div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small">Regards,</div><div class="gmail_default"><font face="verdana, sans-serif">Dženan Zukić, PhD, Senior R&D Engineer, Kitware (Carrboro, N.C.)</font></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, May 30, 2017 at 4:42 AM, Beyer, Benedikt Alexander <span dir="ltr"><<a href="mailto:benedikt.beyer@rwth-aachen.de" target="_blank">benedikt.beyer@rwth-aachen.de</a><wbr>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt">Dear ITK community,</span></font></div>
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<div style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">I am currently writing an academic thesis at the RWTH Aachen University and I work with STL-data that is exported with ITK-Snap. A segmented structure
is exported as an STL-file and then analyzed with VG Studio MAX. The data is used to determine measurement uncertainties created by gaussian filtering. To determine this uncertainty, I compare smoothed data to unsmoothed data. I have a few questions regarding
the gaussian image smoothing setting.</span></span></font></div>
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<li style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">What gaussian filter algorithm does this option use? Eg. Recursive, discrete, robust, etc.</span></span></font></li><li style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">Is this filter a linear or surface filter?</span></span></font></li><li style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">How big is the gaussian kernel? Eg. 3x3, 5x5, etc.</span></span></font></li><li style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">What does the “approximation error max” option do? It has no visual effect on the segmentation.</span></span></font></li><li style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">There seems to be a threshold of the standard deviation at around 0.67. It seems that below this number no smoothing is applied. Is this specific to
the program, or is this depended on the voxel size?</span></span></font></li><li style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">Are there any known influences on measurement uncertainty by gaussian smoothing?</span></span></font></li></ol>
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<div style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">Thank you in advance and with kind regards</span></span></font></div><span class="m_-3258650679128121341HOEnZb"><font color="#888888">
<div style="margin:0"><font face="Calibri,sans-serif" size="2"><span style="font-size:11pt"><span lang="en-US">Benedikt Beyer</span></span></font></div>
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