I'm tring to implement matlab code for Kalman filter as object tracking .There are sample images provided with code.But I tried for another images with different dimensions.It makes .error-'Index exceeds matrix dimensions'

Testtrackkalman.m

clear all

NoOfImg = 8;

Xmsaved = zeros(2, NoOfImg); Xhsaved = zeros(2, NoOfImg);

for k = 1:NoOfImg [xm, ym] = GetBallPos(k); [xh, yh] = TrackKalman(xm, ym);

hold on
plot(xm, ym, 'r*')
plot(xh, yh, 'bs')

pause(1)

Xmsaved(:, k) = [xm ym]';
Xhsaved(:, k) = [xh yh]';

end

figure hold on plot(Xmsaved(1,:), Xmsaved(2,:), '*') plot(Xhsaved(1,:), Xhsaved(2,:), 's')

Trackkalman.m

if true
  % code
end
function [xh, yh] = TrackKalman(xm, ym)
%
%
persistent A H Q R
persistent x P
persistent firstRun

if isempty(firstRun) dt = 1;

A = [ 1  dt  0   0
      0  1   0   0
      0  0   1  dt
      0  0   0   1 ];

H = [ 1  0  0  0
      0  0  1  0 ];

Q = 1.0*eye(4);
R = [ 50  0
       0 50 ];

x = [0, 0, 0, 0]';
P = 100*eye(4);

firstRun = 1;
end

xp = A*x; Pp = A*P*A' + Q;

K = Pp*H'*inv(H*Pp*H' + R);

z = [xm ym]'; x = xp + K*(z - H*xp); P = Pp - K*H*Pp;

xh = x(1); yh = x(3);

function [xc, yc] = GetBallPos1(index) % % persistent imgBg persistent firstRun

if isempty(firstRun) imgBg = imread('Process1/bg1.tif',1);

firstRun = 1;
end

xc = 0; yc = 0;

imgWork = imread(['Process1/', int2str(index), '.tif']); imshow(imgWork)

fore = imabsdiff(imgWork, imgBg); fore = (fore(:,:,1) > 10) | (fore(:,:,2) > 10) | (fore(:,:,3) > 10);

L = logical(fore); stats = regionprops(L, 'area', 'centroid'); area_vector = [stats.Area]; [tmp, idx] = max(area_vector);

centroid = stats(idx(1)).Centroid;

xc = centroid(1) + 15*randn; yc = centroid(2) + 15*randn;

[Sajith Galgamuwa]

Error in GetBallPos (line 27) centroid = stats(idx(1)).Centroid;

Error in TestTrackKalman (line 9) [xm, ym] = GetBallPos(k);

[Image Analyst]

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

Answer 1

[Image Analyst]

stats is probably empty. What does this show

numBlobs = size(stats)

[Sajith Galgamuwa]

? centroid = stats(idx(1)).Centroid;

[Image Analyst]

allCentroids = [stats.Centroid];
xCentroids = allCentroids(1:2:end);
yCentroids = allCentroids(2:2:end);

[Sajith Galgamuwa]

centroid = stats.Centroid;

xc = centroid(1:2:end); yc = centroid(2:2:end);

      Again some errors..*
Too many outputs requested.  Most likely cause is missing [] around left hand side that
has a comma separated list expansion.

Error in GetBallPos (line 27) centroid = stats.Centroid;

Error in TestTrackKalman (line 9) [xm, ym] = GetBallPos(k);

[Image Analyst]

Look at my code. Then look at what the error says is the most likely cause. Anything strike you? Notice how I used brackets, and you didn't, and the error message says that the most likely cause is that you didn't use them. Knowing that, do you still have a question?

Answer 2

[Sajith Galgamuwa]

 centroid = [stats.centroid];  
xc = centroid(1:2:end);
yc = centroid(2:2:end);

I have corrected but,,,,-

Reference to non-existent field 'centroid'.

Error in GetBallPos (line 26)_

centroid = [stats.centroid];

Error in TestTrackKalman (line 9)_

[xm, ym] = GetBallPos(k);

Answer 3

[Sajith Galgamuwa]

centroid = [stats.Centroid];

xc = centroid(1:2:end);

yc = centroid(2:2:end);

Now that part o.k..Thanks

Answer 4

[Sajith Galgamuwa]

But kalman filter part has some problems.

Error using - Matrix dimensions must agree.

Error in TrackKalman (line 37)

x = xp + K*(z - H*xp);

Error in TestTrackKalman (line 10)

[xh, yh] = TrackKalman(xm, ym)

[Sajith Galgamuwa]

Thank you.. all the errors were found.There were sum problems with my images.