<div>Hi Luis, </div>
<div> </div>
<div>Thank you very much for the enlightments. Help me to get better understanding about registration.</div>
<div> </div>
<div>My next questions are:</div>
<div>1. Could you give me some pointers on how to fine tune the parameters?</div>
<div>Is it by looking at the iteration results ? or the steps ? If yes, the how should we change ?</div>
<div> </div>
<div>2. How could I determine if my registration result is 'satisfying' (if there is not such things called 'correct' :D)?</div>
<div>-In the case of using sample volume image with known transformation (e.g. 17 mm y-axis-translated and 10 degree about-z-rotated) (e.g. from BrainWeb), we could always look at the final result and determine that the result if 'satisfying' to a certain accuracy level.
</div>
<div>I don't mind getting the transformation result differ by 1 mm or 1 degree, but sometimes I may got totally far from the known result; differ by 20 mm (totally far, right ? or is that transformation also correct ?</div>
<div> </div>
<div>-What if we are blinded about the transformation ? How to find out ? Is it by trying to resample based on the resulted transformation and overlying the image on top of each other to see if they are aligned ?</div>
<div> </div>
<div>3. If for example, I managed to find out the so-called 'good set' of parameters (e.g. optimizer scales, step size, multiresolution level, etc.) for one particular application (i.e. a pair of volume image), does the set of parameters also be 'good set' of parameters if I used it to register another pair of volume images ? (say, the pair also have the same volume size, same pixel type, same pixel spacing, etc. only differ in the object of the volume; I would expect that the parameter set would be different if the image pairs are of completely different characteristics -
e.g. different pixel type, spacing, etc. Am I right ?)</div>
<div> </div>
<div>Regarding the registration that I am asking about,</div>
<div>here are the informations:</div>
<div> </div>
<div>1) What are the types of images that you are registering: 3D image<span class="q"><br> and what are they characteristics:<br></span>=> Type of image: volume of raw format with the header of .mha. </div>
<div>(fixed: brainweb1e1a10f20.mha, and moving: brainweb1e1a10f20Rot10Tx15.mha) </div>
<div>(obtained from <a onclick="return top.js.OpenExtLink(window,event,this)" href="ftp://public.kitware.com/pub/itk/Data/BrainWeb/" target="_blank">ftp://public.kitware.com/pub/itk/Data/BrainWeb/</a> ). : <br> - Number of Pixels : 181 x 217 x 181 (x,y,z)
<br> - Pixel size in millimeters : 1 mm x 1 mm x 1 mm <br> - Image Modality: Modality=PD<br> - Pixel Type : signed__ short 0 to 4095<br> </div>
<div>Both with known translation of 10 degree about Z, and 17 mm in Z direction.</div>
<div>My parameter set: (please refer to the codes that I attached in my previous email)</div>
<div>Optimizer: RegularStepGradientDescentOptimizer</div>
<div>Transform: Euler3DTransform</div>
<div>Interpolator: BSplineInterpolateImageFunction</div>
<div>Metric: MattesMI</div>
<div>Maximum step length: 0.1 (for level 0), 0.1xcurrentLevel/totalLevel (for subsequent levels)</div>
<div>Minimum step length: 0.001 (for level 0), 0.001xcurrentLevel/totalLevel (for subsequent levels)</div>
<div>Multiresolution of 5 levels.</div>
<div> </div>
<div><span class="q"><br>2) The print out of the output that you get with the<br> Command Observers that you connected to the optimizer.<br></span>=> I attached it below.</div>
<div> </div>
<div>Thank you very much in advance for being patient with my questions.</div>
<div> </div>
<div>Best Regards.</div>
<div><br>Dilla</div>
<div> </div>
<div><br>Output: (too long that it is truncated by the window)<br> 189 -0.464686 [-0.333409, -0.0791086, -0.18898, 0.313457, -1.14818, -0.06734<br>56]<br>190 -0.464737 [-0.333579, -0.079193, -0.189089, 0.313636, -
1.14872, -0.06749<br>07]<br>191 -0.464705 [-0.33355, -0.0793066, -0.189159, 0.313823, -1.14928, -0.06764<br>35]<br>192 -0.464647 [-0.333258, -0.0791319, -0.1892, 0.313984, -1.14976, -0.067774<br>1]<br>193 -0.464676
[-0.333174, -0.0791547 , -0.189116, 0.314173, -1.15032, -0.0679<br>284]<br>194 -0.46469 [-0.333301, -0.0791249, -0.189043, 0.314357, -1.15088, -0.06808<br>18]<br>195 -0.464705 [-0.333472, -0.0791895, -0.189026,
0.314538, -1.15143, -0.0682 <br>324]<br>196 -0.464757 [-0.333496, -0.0792566, -0.189082, 0.314728, -1.15199, -0.0683<br>875]<br>197 -0.464763 [-0.333322, -0.0791368, -0.189182, 0.314905, -1.15253, -0.0685<br>317]<br>
198 -0.464727 [-0.333162 , -0.0791866, -0.189159, 0.31509, -1.15308, -0.06868<br>17]<br>199 -0.464738 [-0.333127, -0.0791232, -0.189156, 0.315279, -1.15365, -0.0688<br>391]<br>Interation: 3<br>0 -0.392653 [-0.369659
, -0.047565, -0.154304, 0.316976, -1.16061, -0.0707262<br>]<br>1 -0.39133 [-0.348296, -0.0316052, -0.16753, 0.318111, -1.1638, -0.0723013]<br>2 -0.388049 [-0.351559, -0.0444719, -0.160742, 0.318708, -1.16524, -0.072850
<br>3]<br>3 -0.391708 [-0.365124, -0.0500949, -0.160552, 0.319606, -1.16802, -0.073737<br>7]<br>4 -0.391349 [-0.360776, -0.0549552, -0.156911, 0.319951, -1.16858, -0.073952<br>7]<br>5 -0.393752 [-0.362297, -0.0621432
, -0.155848, 0.320479 , -1.16949, -0.074128<br>]<br>6 -0.394421 [-0.359762, -0.0595702, -0.15682, 0.320559, -1.16973, -0.0742051<br>]<br>7 -0.394416 [-0.358517, -0.0567285, -0.158868, 0.320733, -1.17018, -0.074327
<br>]<br>8 -0.393478 [-0.359665, -0.0580998, -0.158397, 0.320891, -1.17043, -0.074397<br>3]<br>9 -0.393987 [-0.361272, -0.0581854, -0.158882, 0.321264, -1.17116, -0.074567<br>1]<br>10 -0.393925 [-0.360483, -0.0580834
, -0.158667, 0.321462 , -1.17155, -0.07465<br>25]<br>Interation: 4<br>0 -0.363343 [-0.308178, -0.112454, -0.134598, 0.325839, -1.18073, -0.0796605<br>]<br>1 -0.367377 [-0.323184, -0.0815516, -0.154929, 0.325817, -
1.18304, -0.080738<br>6]<br>2 -0.369751 [-0.299335, -0.0496655, -0.155229, 0.326987, -1.18578, -0.08309]</div>
<div>
<p>3 -0.37072 [-0.304311, -0.0634376, -0.141665, 0.327761, -1.18668, -0.0834733<br>]<br>4 -0.372869 [-0.31178, -0.0658768, -0.123576, 0.329088, -1.18936, -0.0849234<br>]<br>5 -0.375957 [-0.316741, -0.0591062, -
0.1055, 0.329625, -1.19064, -0.0858798]</p>
<p>6 -0.378002 [-0.3081, -0.0567318, -0.1099, 0.32985, -1.1911, -0.086133]<br>7 -0.377799 [-0.298204, -0.0567207, -0.110663, 0.330161, -1.19207, -0.086811<br>6]<br>8 -0.379099 [-0.299722, -0.0533165, -0.107419
, 0.33036, -1.19273, -0.0871248<br>]<br>9 -0.379125 [-0.29793, -0.0526449, -0.102867, 0.330541, -1.19342, -0.0874569<br>]<br>10 -0.379347 [-0.296691, -0.0513088, -0.104569, 0.330599, -1.19355, -0.08756<br>04]<br>
11 - 0.379221 [-0.297418, -0.0517805, -0.103706, 0.33069, -1.19377, -0.087674<br>2]<br> Probe Tag Starts Stops Time<br> registration 1 1 10837.7 <- it is in seconds !!! *damn long*
<br>Result =<br> Angle X (degrees) = -17.0408<br> Angle Y (degrees) = -2.9668<br> Angle Z (degrees) = -5.94191<br> Translation X = 0.33069<br> Translation Y = -1.19377<br> Translation Z = -0.0876742<br> Iterations = 13
<br> Metric value = -0.379401</p></div>
<div>I tried using Powell optimizer, and I got this result: which I consider 'Satisfying' result.</div>
<div> </div>
<div>Probe Tag Starts Stops Time<br> registration 1 1 4759.31<br>Result =<br> Angle X (degrees) = -0.0413042<br> Angle Y (degrees) = 0.0232163<br> Angle Z (degrees) = -
10.141<br> Translation X = 2.46763<br> Translation Y = -17.3549<br> Translation Z = 0.000790069<br> Iterations = 1<br> Metric value = -1.59818<span class="e" id="q_108d411d90fd1187_5"></span></div>