<div dir="ltr"><div>Dear ITK community,</div><div><br></div><div>today I was trying to implement a multi-resolution registration process for 3d images.</div><div><br></div><div>I started from the example in the tutorial. Unfortunately, I've received the following warning:</div><div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">WARNING: In f:\libs\insighttoolkit-4.8.2\modules\numerics\optimizersv4\include\itkObjectToObjectMetric.hxx, line 529<br>MeanSquaresImageToImageMetricv4 (000000006506C020): No valid points were found during metric evaluation. For image metrics, verify that the images overlap appropriately. For instance, you can align the image centers by translation. For point-set metrics, verify that the fixed points, once transformed into the virtual domain space, actually lie within the virtual domain.</blockquote></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">These are the parameters I have used for the multi resolution process:<br><span class="" style="white-space:pre">      </span>const unsigned int numberOfLevels = 3;<br><span class="" style="white-space:pre">  </span>RegistrationType::ShrinkFactorsArrayType shrinkFactorsPerLevel;<br><span class="" style="white-space:pre"> </span>shrinkFactorsPerLevel.SetSize(numberOfLevels);<br><span class="" style="white-space:pre">  </span>shrinkFactorsPerLevel[0] = 4;<br><span class="" style="white-space:pre">   </span>shrinkFactorsPerLevel[1] = 2;<br><span class="" style="white-space:pre">   </span>shrinkFactorsPerLevel[2] = 1;<br><span class="" style="white-space:pre">   </span>RegistrationType::SmoothingSigmasArrayType smoothingSigmasPerLevel;<br><span class="" style="white-space:pre">     </span>smoothingSigmasPerLevel.SetSize(numberOfLevels);<br><span class="" style="white-space:pre">        </span>smoothingSigmasPerLevel[0] = 2;<br><span class="" style="white-space:pre"> </span>smoothingSigmasPerLevel[1] = 1;<br><span class="" style="white-space:pre"> </span>smoothingSigmasPerLevel[2] = 0;<br><span class="" style="white-space:pre"> </span>registration->SetNumberOfLevels(numberOfLevels);<br><span class="" style="white-space:pre">     </span>registration->SetSmoothingSigmasPerLevel(smoothingSigmasPerLevel);<br><span class="" style="white-space:pre">   </span>registration->SetShrinkFactorsPerLevel(shrinkFactorsPerLevel);</blockquote><div><br></div><div>Could you please me explain what is the meaning of this warning?</div><div><br></div><div>By the way, I am working with affine transformations and I have used the transform initializer.</div><div><br></div><div>Best,</div><div><br></div><div>Luigi </div></div>