Can I get length in z dimension from bwlabeln?

I'm using bwlabeln to label objects in a binary 3D image stack. I need to know if each of these objects spans more than one section in the stack. Can anyone recommend a way to do this? Thanks

Answer 1

[Sean de Wolski]

pixlist = regionprops(L,'PixelList')

Now look at pixlist's third column, i.e. z. If numel(unique(z))>1 there are multiple pages.

More - Example

%%Example data:

load mri
D = squeeze(D);
L = bwlabeln(D>50);

%%Engine
pixlist = regionprops(bwconncomp(L),'PixelList');
nobj = numel(pixlist);
for ii = nobj:-1:1
    % multipage = 1, covers multiple pages, 0 does not.
    multipage(ii,1) = numel(unique(pixlist(ii).PixelList(:,3)))>1;    
end

% Find labels of multipage objects
multipageIdx = find(multipage);

% Keep only those in multipages
BW = ismember(L,multipageIdx);

% Relabel
Lmpage = bwlabeln(BW);

%%Check it

% How many multipage objects?
max(Lmpage(:))

% View as movie
implay(Lmpage);

[Tara]

brilliant thank you! Now just have to figure out how to exclude all objects that have that third column = 1. I'm a newbie to MATLAB so will no doubt take me days ;)

[Sean de Wolski]

See More for a full example.