function estimateUn​calibrated​Rectificat​ion

function estimateUncalibratedRectification from page http://www.mathworks.com/help/vision/ref/estimateuncalibratedrectification.html

Could someone please explain what do these data mean? Or how can I adjust?

[x0, y0] = deal(-120, -30); xLim = [0.5, w+0.5] + x0; yLim = [0.5, h+0.5] + y0; outputView = imref2d([h,w], xLim, yLim);

[Houghton]

How to find the value of x0,y0?

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my original images

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after rectification.

Why the object rotated like that?