Difference between revisions of "Kifu: Go game record (kifu) generator"

Revision as of 20:05, 5 August 2008

Image change detection:

Using vertical RGB components sums of a thresholded difference between a reference image and the current one, it is easy to compute the screen coordinates of a played stone

Geometric projection:

It is necessary to map each point from a reference rectangle to a point in the displayed shape, or vice-versa.

Without considering scene, camera or observer parameters. The only data available are the corner coordinates on the projection plane.

Three methods for mapping the coordinates:

http://cipa.icomos.org/fileadmin/papers/potsdam/2001-21-gf01a.pdf

"2.2 Perspective transformation with two vanishing points" (pages 2 and 3, equations 7 and 10)

http://www-prima.imag.fr/jlc/Courses/2002/DEA-IVR.VO/DEA-IVR.VO.S2.pdf

Inverse homography and plane image rectification (page 14)

Or to compute a 3x3 transformation matrix to map any point of the displayed quadrilateral shape to a rectangular shape.

To compute the tranformation matrix, somebody given me this unworking formulae.

(maybe i could just not use it properly) :

X: screen projection coordinates

X': goban corners coordinates

X=[x1 x2 x3 x4; y1 ... y4; 1 ... 1]

X'=[x1' x2' x3' x4'; y1' ... y4'; 1 ... 1]

H=X'Xt(XXt)^-1 (with Xt = transposed matrix of X)

p'=Hp

p'=[a;b;c]

x=a/c

y=b/c

Links:

irc://irc.freenode.net/#kifu

http://www.sourceforge.net/projects/kifu

Perspective transformation: http://cipa.icomos.org/fileadmin/papers/potsdam/2001-21-gf01a.pdf

Inverse homography: http://www-prima.imag.fr/jlc/Courses/2002/DEA-IVR.VO/DEA-IVR.VO.S2.pdf

http://sciences.ch/htmlfr/geometrie/geometrieprojective01.php