calculating the distance

I have a code for tracking a red ball taken from internet real time process,now if i move the redball is it possible to calculate the distance and speed,i have connected a eye robot so i want to calculate the distance of redball moved in order to make the robot move for tha particular distance and with speed

clc;
vid=videoinput('winvideo',1, 'YUY2_640X480');
set(vid, 'FramesPerTrigger', Inf);
set(vid, 'ReturnedColorspace', 'rgb')
vid.FrameGrabInterval =20;

start(vid)
first=getsnapshot(vid);
num=2;
centroid(1,1)=0;
centroid(1,2)=0;
thetaa=0;
diffx=0;
diffy=0;
dx=0;
dy=0;
are1(1)=0;
dist(1)=0;

while(vid.FramesAcquired<=50)

      data = getsnapshot(vid);

      proframe=abs(first-data);

      first=data;
          diff_im = imsubtract(data(:,:,1), rgb2gray(data));

      diff_im = medfilt2(diff_im, [3 3]);

      diff_im = im2bw(diff_im,0.15);

      diff_im = bwareaopen(diff_im,5000);

      bw = bwlabel(diff_im, 8);

      stats = regionprops(bw, 'BoundingBox', 'Centroid','Area');
      figure,imshow(data)

      hold on
      bc=[0 0];
      ar=0;
      for object = 1:length(stats)
          bb = stats(object).BoundingBox;
          bc = stats(object).Centroid;
          ar = stats(object).Area; 
          rectangle('Position',bb,'EdgeColor','r','LineWidth',2)
          plot(bc(1),bc(2), '-m+')
          a=text(bc(1)+15,bc(2), strcat('X: ', num2str(round(bc(1))), ' Y: ', num2str(round(bc(2)))));
          set(a, 'FontName', 'Arial', 'FontWeight', 'bold', 'FontSize', 12, 'Color', 'yellow');
      end
      centroid(num,1)=bc(1);

      centroid(num,2)=bc(2);
      are1(num)=ar;

      if (num-1)~=1
          diffx(num) = (centroid(num,1)-centroid((num-1),1));
          dx(num)=diffx(num);

         diffy(num)  = centroid(num,2)-centroid((num-1),2);
         dy(num)=diffy(num);
         dist(num)=sqrt(((dx(num))^2)+((dy(num))^2));

         areaf(num)= (are1(num)-are1(num-1));

%   serport=RoombaInit(4);
%  
%   if areaf(num)>0
%       travelDist(serport, 0.3,0.4);
%    elseif areaf(num)<0
%        travelDist(serport, 0.3,-0.5);
%   end

   travelDist(serport, 0.3,0.4);

i have specifies a constant for movement ,now i want variables of speed and distance,,plz help

Answer 1

[Pedro]

distance=sum(sqrt(diffx(i)^2+diffy(i)^2)); % i=1:num

velocity=sqrt((diffx(i)/time)^2+(diffy(i)/time)^2); % time betwen num and num-1

I hope this helps, Sheers!