what is wrong with this code??

Question

Kamran Asif 2018-6-25

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/407205-what-is-wrong-with-this-code

评论： Florian Morsch 2018-6-27

this is my code....I'm trying to detect the person and than measure the distance from my stereoCamera...

leftcam= imaq.VideoDevice('winvideo', 2 ,'YUY2_640x480');
rightcam= imaq.VideoDevice('winvideo', 3, 'YUY2_640x480' );
if ~exist('stereoParams','var')
    load ('calibrationSession.mat');
end
ax = axes;
maxDepth = 5;
while true
  I1 = step(leftcam);
  I2 = step(rightcam);
  [J1,J2] = rectifyStereoImages(I1, I2, stereoParams);
  %figure;
  %imshow(stereoAnaglyph(J1, J2));
  %title('Rectified Video Frames');
  frameLeftGray = rgb2gray(J1);
  frameRightGray = rgb2gray(J2);
    %disparity map
    disp = disparity(frameLeftGray, frameRightGray, 'DisparityRange', [0 ,64] );
    %reconstruct 3d scene
    pointCloud = reconstructScene(disp, stereoParams) ./1000;
    z = pointCloud(:, :, 3);
    z(z<0) = NaN;
    z(z>maxDepth) = NaN;
    pointCloud(:,:,3) = z;
    if ~ishandle(ax)
        break;
    else
        pcshow(pointCloud, J1, 'VerticalAxis', 'Y', 'VerticalAxisDir','Down','parent',ax);
        %setting for visualization below..
        xlabel('X (m)');
        ylabel('Y (m)');
        zlabel('Z (m)');
        xlim(ax, [-.8, .8]);
        ylim(ax, [-.8, .8]);
        zlim(ax, [0, maxDepth]);
        daspect(ax, 'manual');
        pbaspect(ax, 'manual')
        drawnow;
  %      view(pcshow,pointCloud);
    end
    %People Detetion
    peopledetector= vision.PeopleDetector('MinSize',[166,83]);
    bboxes= peopledetector.step(frameLeftGray);
        centroids = [round(bboxes(:,1) + bboxes(:, 3) /2), round(bboxes(:, 2) + bboxes(:, 4)/2)];
        centroidsIdx = sub2ind(size(disp), centroids(:, 2), centroids(:, 1));
        X = pointCloud(:, :, 1);
        Y = pointCloud(:, :, 2);
        Z = pointCloud(:, :, 3);
        centroids3D = [X(centroidsIdx), Y(centroidsIdx), Z(centroidsIdx)];
        dists = sqrt(sum(centroids3D .^2, 2));
        labels = cell(1, numel(dists));
        for i= 1:numel(dists)
            labels{i} = sprintf('%0.2f meters',dists(i));
        end
       % dispFrame = insertObjectAnnotation(J1, 'rectangle', bboxes, labels);
        %dispFrame = J1;
        figure
        imshow(insertObjectAnnotation(J1, 'rectangle', bboxes, labels));
  end
  release(leftcam);
  release(rightcam);

this is the error i got....

Error using insertObjectAnnotation
Expected LABEL to be nonempty.
Error in insertObjectAnnotation
Error in insertObjectAnnotation
Error in insertObjectAnnotation
Error in Untitled4 (line 81)
      imshow(insertObjectAnnotation(J1, 'rectangle', bboxes, labels));

.... i'm new to matlab and i have very short time . this is my fyp work.. please help me to solve this problem as soon as possible

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Answer 1

Florian Morsch 2018-6-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/407205-what-is-wrong-with-this-code#answer_326111

在 MATLAB Online 中打开

imshow(insertObjectAnnotation(J1, 'rectangle', bboxes, labels));

https://de.mathworks.com/help/vision/ref/insertobjectannotation.html

You use "labels"-variable and the compiler tells you, that this variable is empty. Its expected to be nonempty, meaning you should check your code (break points help) why there is no value in the variable.

My guess is: You dont detect anything with the PeopleDetector, and so your variable is empty.

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Florian Morsch 2018-6-25

在 MATLAB Online 中打开

Since i dont have the input from your camera i cant tell you if you detect someone with the detector or not.

Your code order is:

Detect something (i assume people) with the detector

Get the bounding box

bboxes= peopledetector.step(frameLeftGray);

Get the centroids

centroids = [round(bboxes(:,1) + bboxes(:, 3) /2), round(bboxes(:, 2) + bboxes(:, 4)/2)];
      centroidsIdx = sub2ind(size(disp), centroids(:, 2), centroids(:, 1));
      X = pointCloud(:, :, 1);
      Y = pointCloud(:, :, 2);
      Z = pointCloud(:, :, 3);
      centroids3D = [X(centroidsIdx), Y(centroidsIdx), Z(centroidsIdx)];

Calculate dists

dists = sqrt(sum(centroids3D .^2, 2));

Get labels

labels = cell(1, numel(dists));

And then you use the labels in

imshow(insertObjectAnnotation(J1, 'rectangle', bboxes, labels));

The compiler tells you, that labels is empty. This means in return labels is empty, which could indicate you get no dists calculation. This might be due to missing centroids, which cant be created because you have no bounding box. I simply cant tell you where your values are missing since i dont have the camera input.

Use breakpoints and step through your code, check for the values you get and find whats missing.

The closest guess i had was: you dont detect anything. The code itself looks fine, but something is missing and i would assume its the detector not detecting anything. Cant tell for sure since i also miss the camera input.

Kamran Asif 2018-6-25