Reply To: Curve Toolbox – Curve lenght

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#1524
David Shattuck
Keymaster

hi Davide –

We don’t have tools for that as part of the package, but if you are familiar with Matlab or C++ you can calculate these lengths pretty easily. If you save out the curves as a .dfc file, you can then read them with one of our file readers.

You can find a Matlab function for reading the dfc file at the bottom of this page: http://brainsuite.org/formats/dfc/. (I think it is out

function [curves,hdr,xml]=readdfc(filename)
% READDFC reads a BrainSuite curve file.
%
% Author : David Shattuck, UCLA Brain Mapping Center
fid=fopen(filename,'rb');
if (fid<0)
    error(['unable to open file ' filename(:)']);
end;
hdr.magic=char(fread(fid,8,'char')');
hdr.version=fread(fid,4,'uchar');
hdr.headerSize=fread(fid,1,'uint32');
hdr.dataStart=fread(fid,1,'uint32');
hdr.metadataOffset=fread(fid,1,'int32');
hdr.subjectDataOffset=fread(fid,1,'int32');
hdr.nCurves=fread(fid,1,'int32');
fseek(fid,hdr.metadataOffset,'bof');
xml=char(fread(fid,hdr.dataStart-hdr.metadataOffset,'char')');
curves=cell(hdr.nCurves,1);
fseek(fid,hdr.dataStart,'bof');
for i=1:hdr.nCurves;
    nPoints=fread(fid,1,'uint32');
    curves{i}=fread(fid,[3 nPoints],'float32')';
end;
fclose(fid);

The curves are represented as a series of points in mm coordinates, so you can compute the path lengths very easily:

function curvelength=curvelength(curve)
curvelength=sum(sqrt(sum((curve(2:size(curve,1),:)-curve(1:size(curve,1)-1,:)).^2,2)));

If you then read in a dfc, you can easily compute the length of any of the curves:

curveset=readdfc('/Applications/BrainSuite18a/svreg/BCI-DNI_brain_atlas/BCI-DNI_brain.right.dfc');
curvelength(curveset{1})

Let us know if that does what you need.

thanks,
David Shattuck