Difference between revisions of "PlayChessWithAWebCam/BoardFinder"

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(finding the chessboard corners)
(Polygons)
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[[File:chessBoard012.jpg|400px]][[File:image012-corners-4x6.jpg|400px]]
 
[[File:chessBoard012.jpg|400px]][[File:image012-corners-4x6.jpg|400px]]
 
[[File:chessBoard013.jpg|400px]][[File:image013-corners-5x7.jpg|400px]]
 
[[File:chessBoard013.jpg|400px]][[File:image013-corners-5x7.jpg|400px]]
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==== Chessboard008 in detail ====
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[[File:chessBoard008.jpg|600px]]
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[[File:image008-corners-7x7.jpg|600px]]
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===== Polygons =====
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The corners detected can be used to fill the 4 corner polygons.
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We don't know the colors of the squares yet but we now it's a chessboard-pattern.
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See https://codegolf.stackexchange.com/questions/63772/determine-the-color-of-a-chess-square
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For the time being we guess and might be wrong:
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[[File:image008-polygons-7x7.jpg|400px]]
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===== Masking =====
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To find out the colors we mask the detected squares.
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 +
[[File:image008-masked-X--7x7.jpg|400px]]
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[[File:image008-masked-O--7x7.jpg|400px]]
 +
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===== Histogram ======
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Now we can create a histogram of the colors found in the
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[[File:image008-histogram-7x7.jpg]]
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===== Color filtering =====
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[[File:image008-colorFiltered-X--7x7.jpg|400px]]
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[[File:image008-colorFiltered-O--7x7.jpg|400px]]

Revision as of 07:51, 1 December 2019

Source Code

see class BoardFinder in module boardfinder tests are in the: test_BoardFinder module

Algorithm

Finding the chessboard

OpenCV has a function findChessboardCorners which is usually used for camera calibration and not really intended for the use case of "real chessboards".

Still it is very helpful and used as a basis for the BoardFinder.

Initializing the BoardFinder

The board finder is initialized with an image. Optionally you can specify the Video instance to be used.

finder = BoardFinder(image,video=video)

finding the chessboard corners

The find method starts the board finding. The Boardfinder will try out different patterns from 7x7 down to 3x3. Since a successfull find is much quicker than an unsuccessful one and since searching a small image is much faster than a big one the width of the searchImages can be specified. The default is 640 pixels. For the 13 tests images the search is even successful when the searchWidth is only 360 pixels. The difference in speed is approximately a factor of 1.5.

found=finder.find(limit=1,searchWidth=360)

Examples

see testMedia source folder

ChessBoard001.jpgImage001-corners-7x7.jpg ChessBoard002.jpgImage002-corners-5x5.jpg ChessBoard003.jpgImage003-corners-4x5.jpg ChessBoard004.jpgImage004-corners-7x7.jpg ChessBoard005.jpgImage005-corners-5x5.jpg ChessBoard006.jpgImage006-corners-5x5.jpg ChessBoard007.jpgImage007-corners-5x5.jpg ChessBoard008.jpgImage008-corners-7x7.jpg ChessBoard009.jpgImage009-corners-7x7.jpg ChessBoard010.jpgImage010-corners-6x7.jpg ChessBoard011.jpgImage011-corners-7x7.jpg ChessBoard012.jpgImage012-corners-4x6.jpg ChessBoard013.jpgImage013-corners-5x7.jpg

Chessboard008 in detail

ChessBoard008.jpg Image008-corners-7x7.jpg

Polygons

The corners detected can be used to fill the 4 corner polygons. We don't know the colors of the squares yet but we now it's a chessboard-pattern. See https://codegolf.stackexchange.com/questions/63772/determine-the-color-of-a-chess-square For the time being we guess and might be wrong: Image008-polygons-7x7.jpg

Masking

To find out the colors we mask the detected squares.

Image008-masked-X--7x7.jpg Image008-masked-O--7x7.jpg

Histogram =

Now we can create a histogram of the colors found in the Image008-histogram-7x7.jpg

Color filtering

Image008-colorFiltered-X--7x7.jpg Image008-colorFiltered-O--7x7.jpg