Error using horzcat Dimensions of matrices being concatenated are not consistent. Please help.

function s=surfMatch(str,name,st,en)
    matches_arr=[];
    total=0;
   unmatches_arr=[];
   unmatch_feature=zeros(1,100);

    for num_images=st:en-1
        disp(['Processing frame:',num2str(num_images),' and ',num2str(num_images+1)]);
        path1=[str,'\',name,'_',num2str(num_images),'.bmp'];
        path2=[str,'\',name,'_',num2str(num_images+1),'.bmp'];
        I1=imread(path1);
        I2=imread(path2);
        img_arr1=rgb2gray(I1);
        img_arr2=rgb2gray(I2);
        f1= detectSURFFeatures(img_arr1);
        f2= detectSURFFeatures(img_arr2);

    matchcount=0;
        h=length(f1);
        g=length(f2);
        disp(['No. of  features in  frame  ',num2str(num_images),'=',num2str(h)]);

        disp(['No. of  features in frame  ',num2str(num_images+1),'=',num2str(g)]);
        [features1,  validf1]  = extractFeatures(img_arr1,  f1.selectStrongest(45));
       [features2, validf2] = extractFeatures(img_arr2, f2.selectStrongest(45));

        %strongestPoints = validf1.selectStrongest(1000);
        %no_of_features1=length(strongestPoints);

            unmatch_feature=horzcat(unmatch_feature,features1);

        %disp(unmatch_feature);
        %disp(['No. of matching features in block ',num2str(num_images),'=',num2str(no_of_features1)]);
        indexPairs = matchFeatures(unmatch_feature, features2);
        matchedIm1  = validf1(indexPairs(:,1),:);
        matchedIm2 = validf2(indexPairs(:,2),:);
       % matchedIm3 = validf2(indexPairs(:,3),:);

        no_of_matchedPts=size(matchedIm1,1);
        %[features3, validf3] = extractFeatures(indexPairs,1);
       % m3 = matchFeatures(features3, features2);
        %m4=length(m3);

        disp(['No. of matching features in block ',num2str(num_images),',',num2str(num_images+1),'=',num2str(no_of_matchedPts)]); 
        matchcount=matchcount+no_of_matchedPts;
        disp(['No. of overall matching features in block ','=',num2str(matchcount)]);
        matches_arr=[matches_arr,no_of_matchedPts];
        disp('No. of matching features of two consecutive  frames stored in array ');
        disp(matches_arr);
        unmatchedIdx1 = true(1, size(features1, 1));
        unmatchedIdx1(indexPairs(:, 1)) = false;
        unmatchedFeatures1 = features1(unmatchedIdx1, :);
        no_of_unmatched=length(unmatchedFeatures1);
        disp(['The number of unmatched features of frame  ',num2str(num_images),'=',num2str(no_of_unmatched)]);
        unmatchedIdx2 = true(1, size(features2, 1));
        unmatchedIdx2(indexPairs(:, 1)) = false;
        unmatchedFeatures2 = features2(unmatchedIdx2, :);
        no_of_unmatched1=length(unmatchedFeatures2);
        disp(['The number of unmatched features of frame  ',num2str(num_images+1),'=',num2str(no_of_unmatched1)]);
        totalunmatchedpoints=no_of_unmatched1+no_of_unmatched;
        disp(['No. of unmatching features in block ',num2str(num_images),',',num2str(num_images+1),'=',num2str(totalunmatchedpoints)]);
        unmatches_arr=[unmatches_arr,totalunmatchedpoints];
        disp('No. of unmatched features stored in array of the two consecutive frames');
        disp(unmatches_arr);
       % total=total+matchedIm1+unmatchedIdx1;
        %t=length(total);
        %disp((indexPairs));
        %[tform, inlierf1, inlierf2] = estimateGeometricTransform(matchedIm1, matchedIm2, 'affine');
        figure;
        showMatchedFeatures(I1,I2, matchedIm1, matchedIm2,'montage'); 
        %g=length(h);
        %disp(['No. of matching features in block ','=',g]);
    end
end

Answer 1

[James Tursa]

Use the debugger to pause the code at the error. Then examine the dimensions of the variables involved and figure out what the problem is. E.g.,

dbstop if error
% Then run your code