MATLAB: Getting x and y for 3d

Question

1.how can i obtain real world X and Y from x and y obtained from an image? 2.is scaling factor in x dirn*x=X and scaling factor in y dirn*y=Y ? if then how could i find the scaling factors?

Answer 1

A=yourPicture;

[H L]=size(A);

dx=theRealLengthOfTheView/H; %this you must know, otherwise you can not scale the image.

dy=theRealWidthOfTheView/L;

figure(1);imagesc(A);

h=impoint;

[y x] = getPosition(h);

X=dx*x;

Y=dy*y;

Where your X and Y will be the real world distances from the origin (0,0) at the top left corner of the picture.