On Sat, Jan 8, 2011 at 12:24 PM, Narendra Sisodiya < naren...@narendrasisodiya.com> wrote:
> I want your guidance in following problem. > > I have a Rectangle with a known height and width. (aspect ration is fixed) > It has a plane surface. Something like cardboard. Or Rectangle Drawn on > wall. > I am now taking image of this rectangle from webcam. > After taking image of this rectangle from webcam, rectangle occupy small > area on image and that is in a form of quadrilateral inside image. I can > calculate the XY location of Rectangle from image , So I have Following > Matrix > > Co-ordinate on image -> Actual real world co-ordinate > _______________________________________ > X1 Y1 -> 0 , 0 > X2 Y2 -> width, 0 > X3 Y3 -> 0, height > X4 Y4 -> width, height > ________________________________________ > > width and height of rectangle is known because I can measure this real > object > X1 Y1 to X4 Y4 are 4 co-ordinate of this object in image. Because it is a > projective transformation, this will be in a shaped of quadrilateral. > > > Now I want to know a matrix operation or any formula, by which I can > convert a given X Y of image into corresponding co-ordinate on rectangle. > I think, this is known as homography. seeing on web, i can find complex > description and formulas which i am unable to understand. > > May you give me exact formula for how to do it. > > Thanks ! > > Also - This code will be useful - I am unable to understand it fully - But i guess , this is doing exactly what i want. http://wiiwhiteboard.cvs.sourceforge.net/viewvc/wiiwhiteboard/source/linux/perspective.py?view=markup
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