what is the function of... ?please explain the statement ' roi'. and ' isempty'

for m=1:size(leftI,1)
    % Set min/max row bounds for image block.
    minr = max(1,m-halfBlockSize);
    maxr = min(size(leftI,1),m+halfBlockSize);
    % Scan over all columns.
    for n=1:size(leftI,2)
        minc = max(1,n-halfBlockSize);
        maxc = min(size(leftI,2),n+halfBlockSize);
        % Compute disparity bounds.
        mind = max( -disparityRange, 1-minc );
        maxd = min( disparityRange, size(leftI,2)-maxc );

          % Construct template and region of interest.
          template = rightI(minr:maxr,minc:maxc);
          templateCenter = floor((size(template)+1)/2);
          roi = [minr+templateCenter(1)-2 ...
                 minc+templateCenter(2)+mind-2 ...
                 1 maxd-mind+1];
          % Lookup proper TemplateMatcher object; create if empty.
          if isempty(tmats{size(template,1),size(template,2)})
              tmats{size(template,1),size(template,2)} = ...
                  video.TemplateMatcher('ROIInputPort',true);
          end
          thisTemplateMatcher = tmats{size(template,1),size(template,2)};

          % Run TemplateMatcher object.
          loc = step(thisTemplateMatcher, leftI, template, roi);
          Dbasic(m,n) = loc(2) - roi(2) + mind;
      end
  end

Answer 1

[Wayne King]

tmats is created as an empty cell array 7x7

The code:

if isempty(tmats{size(template,1),size(template,2)})
            tmats{size(template,1),size(template,2)} = ...
                vision.TemplateMatcher('ROIInputPort',true);
        end

says "if the element of the cell array tmats{4,4} (the size of the template in the row and column dimension the first time through the for loop) is empty, place the System object handle vision.TemplateMatcher('ROIInputPort',true) in that element of the cell array"

The next time through the loop the column location changes as explained in the demo.

[neenu jose]

what does ... indicate?

[Wayne King]

that's just an ellipsis to move the line of code to the next line without generating an error

x = randn(100,1);

mu = ...

mean(x);

% this will error

x = randn(100,1);

mu =

mean(x);

Answer 2

[Image Analyst]

isempty() basically checks to see if the variable has been assigned and has a value or not. roi means "region of interest" and is the portion of the array to operate on.

[neenu jose]

i would like to know what is being done in this statement to find region of interest.

roi = [minr+templateCenter(1)-2 ...

minc+templateCenter(2)+mind-2 ...

1 maxd-mind+1];

[Wayne King]

Hi Neenu, that is just the definition of the region of interest as ImageAnalyst has said. I suggest you place a breakpoint in that for loop and then use F10 to step through it, you will see how the region of interest changes and how the location of where the System object handle placement changes as well.

[neenu jose]

ya..that works!!