<div dir="ltr"><div>Hi,</div>I'm not very familiar with VariableLengthVector but I think it is not the same as a Vector. An itk::CudaImage<itk::Vector<float,3>,2> buffer is not fragmented. In terms of performances, it depends how you use them. In our usage, I think it's more efficient to have all values belonging to a pixel next to each other in memory.<br><div>No, there is no memory reorganization for the GPU, it's a straight copy of the CPU to the GPU. We use textures internally sometimes but this is done when executing the filter.</div><div>Don't hesitate to describe the problem you want to solve, I can try to help...<br></div><div>Simon<br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Feb 21, 2019 at 11:45 PM Kabelitz, Gordian <<a href="mailto:Gordian.Kabelitz@medma.uni-heidelberg.de">Gordian.Kabelitz@medma.uni-heidelberg.de</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">Hi Simon,<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">I asked because of the description of the itk::VectorImage (<a href="https://itk.org/Doxygen/html/classitk_1_1VectorImage.html" target="_blank">https://itk.org/Doxygen/html/classitk_1_1VectorImage.html</a>):<u></u><u></u></span></p>
<p class="MsoNormal"><i><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">“</span></i><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%">Conceptually, a </span></i><code><i><span style="font-size:9pt;color:black;background:white none repeat scroll 0% 0%">VectorImage<
TPixel, 3 ></span></i></code><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%"> is the same as a </span></i><code><i><span style="font-size:9pt;color:black;background:white none repeat scroll 0% 0%"><a href="https://itk.org/Doxygen/html/classitk_1_1Image.html" title="Templated n-dimensional image class." target="_blank"><b><span style="color:rgb(70,101,162);text-decoration:none">Image</span></b></a><
VariableLengthVector< TPixel >, 3 ></span></i></code><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%">. The difference lies in the memory organization. The latter results in a fragmented organization with each
location in the </span><a href="https://itk.org/Doxygen/html/classitk_1_1Image.html" title="Templated n-dimensional image class." target="_blank"><b><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:rgb(70,101,162);background:white none repeat scroll 0% 0%;text-decoration:none">Image</span></b></a></i><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%"> holding
a pointer to an </span></i><code><i><span style="font-size:9pt;color:black;background:white none repeat scroll 0% 0%"><a href="https://itk.org/Doxygen/html/classitk_1_1VariableLengthVector.html" title="Represents an array whose length can be defined at run-time." target="_blank"><b><span style="color:rgb(70,101,162);text-decoration:none">VariableLengthVector</span></b></a></span></i></code><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%"> holding
the actual pixel. The former stores the </span></i><em><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%;font-style:normal">k</span></em><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%"> pixels
instead of a pointer reference, which apart from avoiding fragmentation of memory also avoids storing a 8 bytes of pointer reference for each pixel. The parameter </span></i><em><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%;font-style:normal">k</span></em><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%"> can
be set using </span></i><code><i><span style="font-size:9pt;color:black;background:white none repeat scroll 0% 0%">SetVectorLength</span></i></code><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%">.”<u></u><u></u></span></i></p>
<p class="MsoNormal"><i><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:black;background:white none repeat scroll 0% 0%"><u></u> <u></u></span></i></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">Does it make any performance differences on the CPU algorithms?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">I guess that the memory is reorganized in the rtk::CudaImageFilter to make it more efficient on the GPU (like a new image for each vector component). Or it
is handled in a different way?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">I think it will be more time consuming and error prone to do it by myself since I am not very familiar with GPU memory management.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Calibri","sans-serif";color:rgb(31,73,125)">Gordian<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><b><span style="font-size:10pt;font-family:"Tahoma","sans-serif"" lang="DE">Von:</span></b><span style="font-size:10pt;font-family:"Tahoma","sans-serif"" lang="DE"> Simon Rit [mailto:<a href="mailto:simon.rit@creatis.insa-lyon.fr" target="_blank">simon.rit@creatis.insa-lyon.fr</a>]
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<b>Gesendet:</b> Mittwoch, 20. Februar 2019 16:27<br>
<b>An:</b> Kabelitz, Gordian<br>
<b>Cc:</b> <a href="mailto:rtk-users@public.kitware.com" target="_blank">rtk-users@public.kitware.com</a><br>
<b>Betreff:</b> Re: [Rtk-users] rtk::CudaVectorImage available<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Hi Gordian,<u></u><u></u></p>
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<p class="MsoNormal">I don't think so. We have successfully used images of vectors (e.g., itk::CudaImage<itk::Vector<float,3>,2>) but I have never used VectorImage and I think you would need to rewrite an itk::CudaVectorImage to do so. I'm not sure how difficult
that would be...<u></u><u></u></p>
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<p class="MsoNormal">Simon<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">On Wed, Feb 20, 2019 at 4:13 PM Kabelitz, Gordian <<a href="mailto:Gordian.Kabelitz@medma.uni-heidelberg.de" target="_blank">Gordian.Kabelitz@medma.uni-heidelberg.de</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal"><span lang="DE">Hello,</span><u></u><u></u></p>
<p class="MsoNormal"><span lang="DE"> </span><u></u><u></u></p>
<p class="MsoNormal">I am looking for a ITKCudaCommon datatype that resembles the itk::VectorImage.<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">Is there a possibility to use itk::CudaImage somehow or other workarounds?<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">Thanks in advance,<u></u><u></u></p>
<p class="MsoNormal">Gordian<u></u><u></u></p>
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