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<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font color="#000000" style="" face="arial, sans-serif">Hi, <br>I am trying to get my electrodes to align to the headmodel I am using (obtained from the sample data on the Fieldtrip website). However, I always get errors in ft_electroderealign when I try to do this. I have tried this in multiple different ways and although I think I am using all the parameters right for </font>ft_electroderealign<font color="#000000" style="" face="arial, sans-serif">, I get errors that dont make sense. For example: </font>Error in channelposition (line 348)</p>n = size(lab,2);<br><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font color="#000000" face="arial, sans-serif">Any help would be appreciated!</font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font color="#000000" style="" face="arial, sans-serif"><br></font></p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34)"><font face="arial, sans-serif">% fit electrode coordinates to an individual MRI according to the same</font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34)"><font face="arial, sans-serif">% fiducials (nasion, left & right preauricular points) in both systems</font></p>
<p class="gmail-p2" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(160,32,240)"><font face="arial, sans-serif"><span class="gmail-s1" style="color:rgb(0,0,0)">load(</span>'/Users/amnahyder/Downloads/vol.mat'<span class="gmail-s1" style="color:rgb(0,0,0)">)</span></font></p>
<p class="gmail-p2" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(160,32,240)"><font face="arial, sans-serif"><span class="gmail-s1" style="color:rgb(0,0,0)">mri = ft_read_mri(</span>'/Users/amnahyder/Research/MATLAB/Subject01.mri'<span class="gmail-s1" style="color:rgb(0,0,0)">)</span></font></p>
<p class="gmail-p2" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(160,32,240)"><font face="arial, sans-serif"><span class="gmail-s1" style="color:rgb(0,0,0)">elec = ft_read_sens(</span>'/Users/amnahyder/Research/MATLAB/fieldtrip-20191028/template/electrode/GSN-HydroCel-256.sfp'<span class="gmail-s1" style="color:rgb(0,0,0)">)</span></font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34)"><font face="arial, sans-serif">% ensure that the electrode coordinates are in mm</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">elec = ft_convert_units(elec,<span class="gmail-s2" style="color:rgb(160,32,240)">'mm'</span>); <span class="gmail-s3" style="color:rgb(34,139,34)">% should be the same unit as MRI</span></font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">elec.label{1,1}=<span class="gmail-s2" style="color:rgb(160,32,240)">'nasion'</span>;</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">elec.label{2,1}=<span class="gmail-s2" style="color:rgb(160,32,240)">'lpa'</span>;</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">elec.label{3,1}=<span class="gmail-s2" style="color:rgb(160,32,240)">'rpa'</span>;</font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34)"><font face="arial, sans-serif"><span style="color:rgb(34,34,34)">Nas = elec.chanpos(strcmp(elec.label, </span><span class="gmail-s2" style="color:rgb(160,32,240)">'nasion'</span><span style="color:rgb(34,34,34)">),:);</span><br></font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">Lpa = elec.chanpos(strcmp(elec.label, <span class="gmail-s2" style="color:rgb(160,32,240)">'lpa'</span>),:);</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">Rpa = elec.chanpos(strcmp(elec.label, <span class="gmail-s2" style="color:rgb(160,32,240)">'rpa'</span>),:);</font></p>
<p class="gmail-p4" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;min-height:12px"><span class="gmail-Apple-converted-space"><font face="arial, sans-serif"> </font></span></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">mri.nasion = [90 61 105]</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">mri.lpa = [30 148 151]</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">mri.rpa = [143 148 151]</font></p>
<p class="gmail-p4" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;min-height:12px"><span class="gmail-Apple-converted-space"><font face="arial, sans-serif"> </font></span></p>
<p class="gmail-p5" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34);min-height:12px"><span class="gmail-Apple-converted-space"><font face="arial, sans-serif"> </font></span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34)"><font face="arial, sans-serif"><span class="gmail-s1" style="color:rgb(0,0,0)">vox_Nas = mri.nasion;<span class="gmail-Apple-converted-space"> </span></span>% fiducials saved in mri structure</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">vox_Lpa = mri.lpa;</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">vox_Rpa = mri.rpa;</font></p>
<p class="gmail-p4" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;min-height:12px"><span class="gmail-Apple-converted-space"><font face="arial, sans-serif"> </font></span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34)"><font face="arial, sans-serif"><span class="gmail-s1" style="color:rgb(0,0,0)">vox2head = mri.transform; </span>% transformation matrix of individual MRI</font></p>
<p class="gmail-p5" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34);min-height:12px"><span class="gmail-Apple-converted-space"><font face="arial, sans-serif"> </font></span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34)"><font face="arial, sans-serif"><span style="color:rgb(34,34,34)">head_Nas</span><span class="gmail-Apple-converted-space" style="color:rgb(34,34,34)"> </span><span style="color:rgb(34,34,34)">= ft_warp_apply(vox2head, vox_Nas, </span><span class="gmail-s2" style="color:rgb(160,32,240)">'homogenous'</span><span style="color:rgb(34,34,34)">); </span><span class="gmail-s3">% nasion</span><br></font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">head_Lpa<span class="gmail-Apple-converted-space"> </span>= ft_warp_apply(vox2head, vox_Lpa, <span class="gmail-s2" style="color:rgb(160,32,240)">'homogenous'</span>); <span class="gmail-s3" style="color:rgb(34,139,34)">% Left preauricular</span></font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">head_Rpa<span class="gmail-Apple-converted-space"> </span>= ft_warp_apply(vox2head, vox_Rpa, <span class="gmail-s2" style="color:rgb(160,32,240)">'homogenous'</span>); <span class="gmail-s3" style="color:rgb(34,139,34)">% Right preauricular</span></font></p>
<p class="gmail-p5" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34);min-height:12px"><span class="gmail-Apple-converted-space"><font face="arial, sans-serif"> </font></span></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">cfg = [];</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">cfg.method <span class="gmail-Apple-converted-space"> </span>= <span class="gmail-s2" style="color:rgb(160,32,240)">'fiducial'</span>;</font></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;color:rgb(34,139,34)"><font face="arial, sans-serif"><span style="color:rgb(34,34,34)">cfg.elec </span><span class="gmail-Apple-converted-space" style="color:rgb(34,34,34)"> </span><span style="color:rgb(34,34,34)">= elec;</span><br></font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">cfg.warp = <span class="gmail-s2" style="color:rgb(160,32,240)">'rigidbody'</span>;</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">cfg.target.pos(1,:) = head_Nas<span class="gmail-Apple-converted-space"> </span><span class="gmail-s3" style="color:rgb(34,139,34)">% location of the nose</span></font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">cfg.target.pos(2,:) = head_Lpa <span class="gmail-Apple-converted-space"> </span><span class="gmail-s3" style="color:rgb(34,139,34)">% location of the left ear</span></font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">cfg.target.pos(3,:) = head_Rpa <span class="gmail-Apple-converted-space"> </span><span class="gmail-s3" style="color:rgb(34,139,34)">% location of the right ear</span></font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">cfg.target.label<span class="gmail-Apple-converted-space"> </span>= {<span class="gmail-s2" style="color:rgb(160,32,240)">'nasion'</span>, <span class="gmail-s2" style="color:rgb(160,32,240)">'lpa'</span>, <span class="gmail-s2" style="color:rgb(160,32,240)">'rpa'</span>}</font></p>
<p class="gmail-p4" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;min-height:12px"><span class="gmail-Apple-converted-space"><font face="arial, sans-serif"> </font></span></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">cfg.fiducial = {<span class="gmail-s2" style="color:rgb(160,32,240)">'nasion'</span>, <span class="gmail-s2" style="color:rgb(160,32,240)">'lpa'</span>, <span class="gmail-s2" style="color:rgb(160,32,240)">'rpa'</span>};</font></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">elec_new = ft_electroderealign(cfg);</font></p>
<p class="gmail-p4" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;min-height:12px"><span class="gmail-Apple-converted-space" style=""><font face="arial, sans-serif" style=""> </font></span></p></div>