function [sens] = ft_read_sens(filename, varargin)

% FT_READ_SENS read sensor positions from various manufacturer specific files. See

% further down for the list of file types that are supported.

%

% Use as

% elec = ft_read_sens(filename, 'senstype', 'eeg', ...) % for EEG electrodes

% grad = ft_read_sens(filename, 'senstype', 'meg', ...) % for MEG gradiometers

% opto = ft_read_sens(filename, 'senstype', 'nirs', ...) % for NIRS optodes

%

% Additional options should be specified in key-value pairs and can be

% 'fileformat' = string, see the list of supported file formats (the default is determined automatically)

% 'senstype' = string, can be 'eeg', 'meg' or 'nirs', specifies which type of sensors to read from the file (default = 'eeg')

% 'coordsys' = string, 'head' or 'dewar' (default = 'head')

% 'coilaccuracy' = scalar, can be empty or a number (0, 1 or 2) to specify the accuracy (default = [])

% 'coildeffile' = string, can be empty, to specify a coil_def.dat file if coilaccuracy ~= []

% 'readbids' = string, 'yes', no', or 'ifmakessense', whether to read information from the BIDS sidecar files (default = 'ifmakessense')

%

% The electrode, gradiometer and optode structures are defined in more detail

% in FT_DATATYPE_SENS.

%

% Files from the following acquisition systems and analysis platforms file formats

% are supported.

% asa_elc besa_elp besa_pos besa_sfp yokogawa_ave yokogawa_con yokogawa_raw 4d

% 4d_pdf 4d_m4d 4d_xyz ctf_ds ctf_res4 itab_raw itab_mhd netmeg neuromag_fif

% neuromag_mne neuromag_mne_elec neuromag_mne_grad polhemus_fil polhemus_pos

% zebris_sfp spmeeg_mat eeglab_set localite_pos artinis_oxy3 artinis_oxy4

% artinis_oxy5 artinis_oxyproj yorkinstruments_hdf5 matlab

%

% See also FT_READ_HEADER, FT_DATATYPE_SENS, FT_PREPARE_VOL_SENS, FT_COMPUTE_LEADFIELD,

% Copyright (C) 2005-2022 Robert Oostenveld

%

% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org

% for the documentation and details.

%

% FieldTrip is free software: you can redistribute it and/or modify

% it under the terms of the GNU General Public License as published by

% the Free Software Foundation, either version 3 of the License, or

% (at your option) any later version.

%

% FieldTrip is distributed in the hope that it will be useful,

% but WITHOUT ANY WARRANTY; without even the implied warranty of

% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

% GNU General Public License for more details.

%

% You should have received a copy of the GNU General Public License

% along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.

%

% $Id$

% optionally get the data from the URL and make a temporary local copy

filename = fetch_url(filename);

% get the options

fileformat = ft_getopt(varargin, 'fileformat', ft_filetype(filename));

senstype = ft_getopt(varargin, 'senstype'); % can be eeg/meg/nirs, default is automatic and eeg when both meg+eeg are present

coordsys = ft_getopt(varargin, 'coordsys', 'head'); % this is used for ctf and neuromag_mne, it can be head or dewar

coilaccuracy = ft_getopt(varargin, 'coilaccuracy'); % empty, or a number between 0 to 2

coildeffile = ft_getopt(varargin, 'coildeffile'); % empty, or a filename

readbids = ft_getopt(varargin, 'readbids', 'ifmakessense');

realtime = any(strcmp(fileformat, {'fcdc_buffer', 'ctf_shm', 'fcdc_mysql'}));

if realtime

% skip the rest of the initial checks to increase the speed for realtime operation

else

% test whether the file exists

if ~exist(filename, 'file')

ft_error('file ''%s'' does not exist', filename);

end

end

% start with an empty electrode, gradiometer or optode definition

sens = [];

% deal with data that is organized according to BIDS

if strcmp(readbids, 'yes') || strcmp(readbids, 'ifmakessense')

[p, f, x] = fileparts(filename);

% check whether it a BIDS dataset

isbids = startsWith(f, 'sub-');

if isbids

tsvfile = bids_sidecar(filename, 'electrodes');

if ~isempty(tsvfile) && (isempty(senstype) || strcmp(senstype, 'eeg'))

% read the electrodes.tsv file

electrodes_tsv = ft_read_tsv(tsvfile);

sens = [];

sens.label = electrodes_tsv.name;

sens.elecpos = [electrodes_tsv.x electrodes_tsv.y electrodes_tsv.z];

% also read the electrodes.json file

[p, f] = fileparts(tsvfile);

jsonfile = fullfile(p, [f '.json']);

if exist(jsonfile, 'file')

electrodes_json = ft_read_json(jsonfile);

ft_warning('the content of the electrodes.json is not used')

% FIXME do something with the content

end

% also read the coordsystem.json file

coordsysfile = bids_sidecar(filename, 'coordsystem');

if exist(coordsysfile, 'file')

coordsys_json = ft_read_json(coordsysfile);

ft_warning('the content of the coordsystem.json is not used')

% FIXME do something with the content

end

end

end

end

switch fileformat

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% gradiometer information is always stored in the header of the MEG dataset

% hence we use the standard fieldtrip/fileio ft_read_header function

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

case {'ctf_ds', 'ctf_res4', 'ctf_old', 'neuromag_fif', 'neuromag_mne', '4d', '4d_pdf', '4d_m4d', '4d_xyz', 'yokogawa_ave', 'yokogawa_con', 'yokogawa_raw', 'ricoh_ave', 'ricoh_con', 'itab_raw' 'itab_mhd', 'netmeg'}

hdr = ft_read_header(filename, 'headerformat', fileformat, 'coordsys', coordsys, 'coilaccuracy', coilaccuracy, 'coildeffile', coildeffile, 'readbids', readbids);

% sometimes there can also be electrode position information in the header

if isfield(hdr, 'elec') && isfield(hdr, 'grad')

if isempty(senstype)

% set the default

ft_warning('both electrode and gradiometer information is present, returning the electrode information by default');

senstype = 'eeg';

end

switch lower(senstype)

case 'eeg'

sens = hdr.elec;

case 'meg'

sens = hdr.grad;

otherwise

ft_error('incorrect specification of senstype');

end

elseif isfield(hdr, 'grad')

sens = hdr.grad;

elseif isfield(hdr, 'elec')

sens = hdr.elec;

else

ft_error('there is no electrode nor gradiometer information present in the header');

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% optode information is mostly stored in the header of the NIRS dataset

% hence we use the standard fieldtrip/fileio ft_read_header function

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

case {'homer_nirs', 'snirf', 'artinis_oxy3', 'artinis_oxy4', 'artinis_oxy5', 'artinis_oxyproj', 'nirx_wl1', 'nirx_wl2', 'nirx_tpl'}

hdr = ft_read_header(filename, 'headerformat', fileformat, 'coordsys', coordsys, 'readbids', readbids);

if isfield(hdr, 'opto')

sens = hdr.opto;

else

ft_error('there is no optode information present in the header');

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% read the content from various files that contain EEG electrode positions

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

case 'asa_elc'

sens = read_asa_elc(filename);

case 'polhemus_pos'

sens = read_polhemus_pos(filename);

case 'besa_elp'

fid = fopen_or_error(filename);

% these files seem to come in different formats with 3, 4 or 5 columns

% see http://wiki.besa.de/index.php?title=Channel_Definition_File_Formats

% read the first two lines to determine the number of columns

columns1 = length(strsplit(strtrim(fgetl(fid))));

columns2 = length(strsplit(strtrim(fgetl(fid))));

fseek(fid, 0, 'bof');

if columns1==1 && columns2>1

% EEGLAB includes ELP files that start with a line with the number of electrodes

% skip the first line

columns1 = columns2;

fgetl(fid);

end

switch columns1

case 3

% 3-column: label, azimuth, elevation

tmp = textscan(fid, '%s%f%f');

type = repmat({'EEG'}, size(tmp{1}));

label = tmp{1};

theta = tmp{2};

phi = tmp{3};

radius = repmat(85, size(tmp{1}));

ft_warning('assuming a head radius of 85 mm');

case 4

% 4-column: type, label, azimuth, elevation

tmp = textscan(fid, '%s%s%f%f');

type = tmp{1};

label = tmp{2};

theta = tmp{3};

phi = tmp{4};

radius = repmat(85, size(label));

ft_warning('assuming a head radius of 85 mm');

case 5

% 5-column: type, label, azimuth, elevation, radius

tmp = textscan(fid, '%s%s%f%f%f');

type = tmp{1};

label = tmp{2};

theta = tmp{3};

phi = tmp{4};

radius = tmp{5};

otherwise

ft_error('unsupported file format for .elp');

end

fclose(fid);

radians = @(degree) degree*pi/180;

x = radius .* cos(radians(phi)) .* sin(radians(theta));

y = radius .* sin(radians(theta)) .* sin(radians(phi));

z = radius .* cos(radians(theta));

sel = strcmpi(type, 'EEG') | strcmpi(type, 'SCP') | strcmpi(type, 'REF');

sens.elecpos = [x(sel) y(sel) z(sel)];

sens.chanpos = [x(sel) y(sel) z(sel)];

sens.label = label(sel);

sens.unit = 'mm';

sel = strcmpi(type, 'FID');

if any(sel)

sens.fid.pos = [x(sel) y(sel) z(sel)];

sens.fid.label = label(sel);

end

case 'besa_pos'

tmp = importdata(filename);

if ~isnumeric(tmp)

ft_error('unexpected file format for fileformat=besa_pos')

end

[nchan,nrow] = size(tmp);

if nrow==3

sens.pos = tmp;

elseif nrow==9

pos1 = tmp(:,1:3); % bottom coil

pos2 = tmp(:,4:6); % top coil

ori = tmp(:,7:9); % orientation of bottom coil

sens.pos = [pos1; pos2];

sens.ori = [ori; ori];

sens.tra = [eye(nchan) -eye(nchan)];

else

ft_error('unexpected file format for fileformat=besa_pos')

end

[p, f, x] = fileparts(filename);

elpfile = fullfile(p, [f '.elp']);

elafile = fullfile(p, [f '.ela']);

if exist(elpfile, 'file')

ft_warning('reading channel labels from %s', elpfile);

% read the channel names from the accompanying ELP file

lbl = importdata(elpfile);

sens.label = strrep(lbl.textdata(:,2) ,'''', '');

elseif exist(elafile, 'file')

ft_warning('reading channel labels from %s', elafile);

% read the channel names from the accompanying ELA file

lbl = importdata(elafile);

lbl = strrep(lbl, 'MEG ', ''); % remove the channel type

lbl = strrep(lbl, 'EEG ', ''); % remove the channel type

sens.label = lbl;

else

% the file does not have channel labels in it

ft_warning('creating fake channel names for besa_pos');

for i=1:nchan

sens.label{i} = sprintf('%03d', i);

end

end

case 'besa_sfh'

sfh = readBESAsfh(filename);

sens.label = sfh.SurfacePointsLabels(:);

sens.elecpos = sfh.SurfacePointsCoordinates(:,1:3);

sel = true(sfh.NrOfPoints, 1);

for i=1:sfh.NrOfPoints

tok = tokenize(sens.label{i}, '_');

sens.label{i} = tok{2};

sel(i) = ~strcmp(tok{1}, 'Fid');

end

sens.label = sens.label(sel);

sens.elecpos = sens.elecpos(sel,:);

case 'besa_sfp'

[lab, pos] = read_besa_sfp(filename);

sens.label = lab;

sens.elecpos = pos;

case 'bioimage_mgrid'

sens = read_bioimage_mgrid(filename);

case {'curry_dat', 'curry_cdt'}

hdr = ft_read_header(filename);

if ~isempty(hdr.orig.sensorpos)

sens.elecpos = hdr.orig.sensorpos';

sens.label = hdr.label(1:size(sens.elecpos, 1));

end

case 'fcdc_buffer'

% the online header should have a binary blob with the sensor information

hdr = ft_read_header(filename, 'headerformat', fileformat);

if isfield(hdr, 'orig') && isfield(hdr.orig, 'neuromag_header')

hdr = decode_fif(hdr.orig.neuromag_header);

end

if isfield(hdr, 'orig') && isfield(hdr.orig, 'ctf_res4')

hdr = decode_res4(hdr.orig.ctf_res4);

end

if isempty(senstype)

% set the default

ft_warning('both electrode and gradiometer information is present, returning the electrode information by default');

senstype = 'eeg';

end

switch lower(senstype)

case 'eeg'

sens = hdr.elec;

case 'meg'

sens = hdr.grad;

otherwise

ft_error('incorrect specification of senstype');

end

case 'neuromag_mne_grad'

% the file can contain both, force reading the gradiometer info

% note that this functionality overlaps with senstype=eeg/meg

hdr = ft_read_header(filename, 'headerformat', 'neuromag_mne', 'coordsys', coordsys, 'coilaccuracy', coilaccuracy, 'coildeffile', coildeffile);

sens = hdr.grad;

case 'neuromag_mne_elec'

% the file can contain both, force reading the electrode info

% note that this functionality overlaps with senstype=eeg/meg

hdr = ft_read_header(filename, 'headerformat', 'neuromag_mne', 'coordsys', coordsys, 'coilaccuracy', coilaccuracy, 'coildeffile', coildeffile);

sens = hdr.elec;

case {'spmeeg_mat', 'eeglab_set'}

% this is for EEG formats where electrode positions can be stored with the data

hdr = ft_read_header(filename, 'coordsys', coordsys, 'coilaccuracy', coilaccuracy, 'coildeffile', coildeffile);

if isfield(hdr, 'grad')

sens = hdr.grad;

elseif isfield(hdr, 'elec')

sens = hdr.elec;

else

ft_error('no electrodes or gradiometers found in the file')

end

case 'polhemus_fil'

% these are created at the FIL in London with a polhemus tracker

[sens.fid.pos, sens.pos, sens.fid.label] = read_polhemus_fil(filename, 0);

% the file does not have channel labels in it

ft_warning('no channel names in polhemus file, using numbers instead');

for i=1:size(sens.pos, 1)

sens.label{i} = sprintf('%03d', i);

end

case 'matlab'

% MATLAB files can contain all sensor arrays

matfile = filename; % this solves a problem with the MATLAB compiler v3

var = whos('-file', filename);

sel = intersect({'elec', 'grad', 'opto', 'sens', 'elc'}, {var(:).name});

if numel(sel)==1

% read the specific variable

sens = loadvar(matfile, sel{1});

else

% read whatever variable is in the file, this will error if the file contains multiple variables

sens = loadvar(matfile);

end

if ft_datatype(sens, 'layout')

ft_error('"%s" contains a 2D layout for plotting, not 3D electrode positions', filename);

end

case 'zebris_sfp'

% these are created by a Zebris tracker, at CRC in Liege at least.

[sens.fid.pos, sens.chanpos, sens.fid.label, sens.label] = read_zebris(filename, 0);

% convert to columns

sens.label = sens.label(:);

sens.fid.label = sens.fid.label(:);

case '4d_el_ascii'

fid = fopen_or_error(filename, 'rt');

c = textscan(fid, '%s%s%f%f%f');

l = c{:,1}; % label

s = c{:,2}; % status, it can be 'Collected' or empty

x = c{:,3};

y = c{:,4};

z = c{:,5};

% shift the columns with one where the status is not specified

sel = isnan(z);

z(sel) = y(sel);

y(sel) = x(sel);

x(sel) = str2double(s(sel));

s(sel) = {''};

fclose(fid);

if false

% return all positions, including the ones that do not correspond to

% electrodes per see, such as the fiducials and localizer coils

sens = [];

sens.label = l;

sens.elecpos = [x y z];

else

% split the electrodes and fiducials

% this is consistent with zebris_sfp and with the output of ft_read_headshape

sens = [];

sens.label = l(~sel);

sens.elecpos = [x(~sel) y(~sel) z(~sel)];

sens.fid.label = l(sel);

sens.fid.pos = [x(sel) y(sel) z(sel)];

end

case {'localite_pos', 'localite_ins'}

if ~usejava('jvm') % Using xml2struct requires java

fid = fopen_or_error(filename);

% Read marker-file and store contents in cells of strings

tmp = textscan(fid,'%s');

fclose(fid);

% Search for cells that contain coordinates

selx = strncmp('data0',tmp{1},5);

sely = strncmp('data1',tmp{1},5);

selz = strncmp('data2',tmp{1},5);

sellab = strncmp('description',tmp{1},5);

% Extract cells that contain coordinates

xtemp = tmp{1}(selx);

ytemp = tmp{1}(sely);

ztemp = tmp{1}(selz);

labtemp = tmp{1}(sellab);

% Determine which channels are set. In localite channels that are not set

% automatically receive coordinates [0, 0, 0] and should therefore

% be discarded.

settemp = tmp{1}(strncmp('set',tmp{1},3));

selset = strncmp('set="f',settemp,6);

% Remove channels that are not set

xtemp(selset) = [];

ytemp(selset) = [];

ztemp(selset) = [];

labtemp(selset) = [];

% Convert cells that contain coordinates from string to double

x = [];

y = [];

z = [];

lbl = [];

for i=1:numel(xtemp)

x(i,1) = str2double(xtemp{i}(8:end-1));

y(i,1) = str2double(ytemp{i}(8:end-1));

z(i,1) = str2double(ztemp{i}(8:end-3));

lbl{i,1} = labtemp{i}(14:end-1);

end

% Create and fill sens structure

sens = [];

sens.elecpos = [x y z];

sens.chanpos = sens.elecpos;

sens.label = lbl;

else

tmp = xml2struct(filename);

sens = [];

% Loop through structure obtained from xml-file and store

% coordinate information into sens structure of channels that are

% set.

for i=1:numel(tmp)

if strcmp(tmp(i).Marker.set, 'true')

sens.elecpos(i,1) = str2double(tmp(i).Marker.ColVec3D.data0);

sens.elecpos(i,2) = str2double(tmp(i).Marker.ColVec3D.data1);

sens.elecpos(i,3) = str2double(tmp(i).Marker.ColVec3D.data2);

sens.label{i} = tmp(i).Marker.description;

end

end

sens.chanpos = sens.elecpos;

end

case 'easycap_txt'

% Read the file and store all contents in cells of strings

fid = fopen_or_error(filename);

tmp = textscan(fid,'%s%s%s%s');

fclose(fid);

sens = [];

if all(cellfun(@isempty, tmp{4}))

% it contains theta and phi

sens.label = tmp{1}(2:end);

theta = cellfun(@str2double, tmp{2}(2:end));

phi = cellfun(@str2double, tmp{3}(2:end));

radians = @(degree) degree*pi/180;

ft_warning('assuming a head radius of 85 mm');

x = 85 * cos(radians(phi)) .* sin(radians(theta));

y = 85 * sin(radians(theta)) .* sin(radians(phi));

z = 85 * cos(radians(theta));

sens.unit = 'mm';

sens.elecpos = [x y z];

sens.chanpos = [x y z];

else

% it contains X, Y, Z

sens.label = tmp{1}(2:end);

x = cellfun(@str2double, tmp{2}(2:end));

y = cellfun(@str2double, tmp{3}(2:end));

z = cellfun(@str2double, tmp{4}(2:end));

sens.elecpos = [x y z];

sens.chanpos = [x y z];

end

case 'neuromag_iso'

ft_hastoolbox('mne', 1);

FIFF = fiff_define_constants();

[fid, tree, dir] = fiff_open(filename);

isotrak = fiff_dir_tree_find(tree, FIFF.FIFFB_ISOTRAK);

sel = find([isotrak.dir.kind]==FIFF.FIFF_DIG_POINT);

sens = [];

sens.elecpos = nan(numel(sel),3);

sens.chanpos = nan(numel(sel),3);

coordsys = nan(numel(sel),1);

for i=sel

tag = fiff_read_tag(fid,isotrak.dir(i).pos);

sens.elecpos(i,:) = tag.data.r;

sens.chanpos(i,:) = tag.data.r;

coordsys(i) = tag.data.coord_frame;

end

fclose(fid);

if all(coordsys==FIFF.FIFFV_COORD_DEVICE)

sens.coordsys = 'device';

elseif all(coordsys==FIFF.FIFFV_COORD_ISOTRAK)

sens.coordsys = 'isotrak';

elseif all(coordsys==FIFF.FIFFV_COORD_HPI)

sens.coordsys = 'hpi';

elseif all(coordsys==FIFF.FIFFV_COORD_HEAD)

sens.coordsys = 'head';

else

sens.coordsys = 'unknown';

end

ft_warning('creating fake channel names for neuromag_iso');

for i=1:size(sens.chanpos,1)

sens.label{i} = sprintf('%d', i);

end

case 'neuromag_cal'

dat = cell(1,14);

[dat{:}] = textread(filename, '%s%f%f%f%f%f%f%f%f%f%f%f%f%f');

label = dat{1};

x = dat{2};

y = dat{3};

z = dat{4};

rot = cat(2, dat{5:13});

cal = dat{14}; % ??

% construct the sensor structucture

% it seems that the channel positions are expressed in dewar cordinates

% it would be possible to use coil_def.dat to construct the coil positions

sens.label = label;

sens.chanpos = [x y z];

case '3dslicer_fscv'

csvData = readtable(filename, 'FileType', 'text');

sens.label = csvData.label;

sens.elecpos = [csvData.x,csvData.y,csvData.z];

case 'brainsight_txt'

ws = warning('off', 'MATLAB:table:ModifiedAndSavedVarnames');

txtData = readtable(filename, 'FileType', 'text', 'Delimiter', '\t', 'ReadVariableNames', true);

warning(ws); % revert to the previous warning state

sens.label = txtData{:,1};

sens.elecpos = [txtData.Loc_X txtData.Loc_Y txtData.Loc_Z];

case 'yorkinstruments_hdf5'

acquisition='default';

if isempty(senstype)

% set the default

ft_warning('both electrode and gradiometer information is present, returning the electrode information by default');

senstype = 'eeg';

end

hdr=ft_read_header(filename);

%i will be the channel index, sens_i is the sensor index

sens_i=0;

for i=1:hdr.nChans

if string(hdr.chantype{i})==upper(senstype)

sens_i = sens_i+1;

sens.chantype{sens_i,1} = hdr.chantype{i};

try

sens.chanpos(sens_i,1:3) = h5read(filename,['/config/channels/' hdr.label{i} '/position']);

sens.chanori(sens_i,1:3) = h5read(filename,['/config/channels/' hdr.label{i} '/orientation']);

sens.chanunit{sens_i,1} = hdr.chanunit{i};

sens.coilori(sens_i,1:3) = sens.chanori(sens_i,1:3);

sens.coilpos(sens_i,1:3) = sens.chanpos(sens_i,1:3);

sens.label{sens_i,1} = hdr.label{i};

catch

error('Error reading channel %i sensor details.',i);

end

else

continue

end

end

if sens_i<1

error('No data corresponding to the chosen sensor type (%s) found.',senstype);

end

sens.tra = eye(sens_i);

sens.type= 'yorkinstruments248';

if isempty(coordsys)

coordsys = 'dewar';

end

if strcmp(coordsys, 'head')

try

tCCStoMegscanScs = h5read(filename, [strcat('/acquisitions/', char(string(acquisition))) '/ccs_to_scs_transform']);

T = maketform('affine', tCCStoMegscanScs);

sens.coilpos = tformfwd(T, sens.chanpos(:,1), sens.chanpos(:,2), sens.coilpos(:,3));

R = tCCStoMegscanScs(1:3,1:3); % (mm)

sens.coilori = sens.coilori * R;

sens.chanpos=sens.coilpos;

sens.chanori=sens.coilori;

catch

error('No dewar to head transform available in hdf5 file');

end

end

otherwise

if ~isempty(sens)

% the electrode or optode information has been read from the BIDS sidecar file

else

ft_error('unknown fileformat for electrodes or gradiometers');

end

end % switch fileformat

% ensure that the sensor description is up-to-date

% this will also add chantype and units to the sensor array if missing

sens = ft_datatype_sens(sens);

% ensure that the output is consistent with the type requested by the user

if strcmpi(senstype, 'meg')

assert(isfield(sens,'coilpos'), 'cannot read gradiometer information from %s', filename);

elseif strcmpi(senstype, 'eeg')

assert(isfield(sens,'elecpos'), 'cannot read electrode information from %s', filename);

elseif strcmpi(senstype, 'nirs')

assert(isfield(sens,'optopos'), 'cannot read optode information from %s', filename);

else

% it is empty if not specified by the user, in that case either one is fine

end