The term #define SQUARE_SIZE_IN_MM is bit confusing. Does it mean area or length of each side of the squares in the chessboard pattern. For example, if a chessboard pattern with square shaving each side as 3cm is used, then SQUARE_SIZE_IN_MM shoule be 90 (which is area) or 30 (which is length of each side of the square) . Please confirm. Thanks in advance.
the side length is mean, so it would be 30 in your example.