MATLAB image corner coordinates & referncing to cell arrays
- by James
Hi,
I am having some problems comparing the elements in different cell arrays.
The context of this problem is that I am using the bwboundaries function in MATLAB to trace the outline of an image. The image is of a structural cross section and I am trying to find if there is continuity throughout the section (i.e. there is only one outline produced by the bwboundaries command).
Having done this and found where the is more than one section traced (i.e. it is not continuous), I have used the cornermetric command to find the corners of each section. The code I have is:
%% Define the structural section as a binary matrix (Image is an I-section with the web broken)
bw(20:40,50:150) = 1;
bw(160:180,50:150) = 1;
bw(20:60,95:105) = 1;
bw(140:180,95:105) = 1;
Trace = bw;
[B] = bwboundaries(Trace,'noholes'); %Traces the outer boundary of each section
L = length(B); % Finds number of boundaries
if L > 1
disp('Multiple boundaries') % States whether more than one boundary found
end
%% Obtain perimeter coordinates
for k=1:length(B) %For all the boundaries
perim = B{k}; %Obtains perimeter coordinates (as a 2D matrix) from the cell array
end
%% Find the corner positions
C = cornermetric(bw);
Areacorners = find(C == max(max(C))) % Finds the corner coordinates of each boundary
[rowindexcorners,colindexcorners] = ind2sub(size(Newgeometry),Areacorners)
% Convert corner coordinate indexes into subcripts, to give x & y coordinates (i.e. the same format as B gives)
%% Put these corner coordinates into a cell array
Cornerscellarray = cell(length(rowindexcorners),1); % Initialises cell array of zeros
for i =1:numel(rowindexcorners)
Cornerscellarray(i) = {[rowindexcorners(i) colindexcorners(i)]};
%Assigns the corner indicies into the cell array
%This is done so the cell arrays can be compared
end
for k=1:length(B) %For all the boundaries found
perim = B{k}; %Obtains coordinates for each perimeter
Z = perim; % Initialise the matrix containing the perimeter corners
Sectioncellmatrix = cell(length(rowindexcorners),1);
for i =1:length(perim)
Sectioncellmatrix(i) = {[perim(i,1) perim(i,2)]};
end
for i = 1:length(perim)
if Sectioncellmatrix(i) ~= Cornerscellarray
Sectioncellmatrix(i) = [];
%Gets rid of the elements that are not corners, but keeps them associated with the relevent section
end
end
end
This creates an error in the last for loop. Is there a way I can check whether each cell of the array (containing an x and y coordinate) is equal to any pair of coordinates in cornercellarray? I know it is possible with matrices to compare whether a certain element matches any of the elements in another matrix. I want to be able to do the same here, but for the pair of coordinates within the cell array.
The reason I don't just use the cornercellarray cell array itself, is because this lists all the corner coordinates and does not associate them with a specific traced boundary.
