Detect ChArUco Diamond markers

[diamondCorners, diamondIds] = cv.detectCharucoDiamond(img, markerCorners, markerIds, squareMarkerLengthRate)
[...] = cv.detectCharucoDiamond(..., 'OptionName',optionValue, ...)

Input

• img input image necessary for corner subpixel (8-bit grayscale or color).
• markerCorners cell array of detected marker corners from cv.detectMarkers function {{[x,y],..}, ..}.
• markerIds vector of marker ids in markerCorners (0-based).
• squareMarkerLengthRate rate between square and marker length: squareMarkerLengthRate = squareLength/markerLength. The real units are not necessary.

Output

• diamondCorners output list of detected diamond corners (4 corners per diamond). The order is the same than in marker corners: top left, top right, bottom right and bottom left. Similar format than the corners returned by cv.detectMarkers (e.g {{[x y],..}, ..}).
• diamondIds ids of the diamonds in diamondCorners (0-based). The id of each diamond is in fact a vector of four integers, so each diamond has 4 ids, which are the ids of the aruco markers composing the diamond.

Options

• CameraMatrix Optional 3x3 camera calibration matrix A = [fx 0 cx; 0 fy cy; 0 0 1].
• DistCoeffs Optional vector of camera distortion coefficients [k1,k2,p1,p2,k3,k4,k5,k6,s1,s2,s3,s4] of 4, 5, 8 or 12 elements.

This function detects Diamond markers from the previous detected ArUco markers. The diamonds are returned in the diamondCorners and diamondIds parameters. If camera calibration parameters are provided, the diamond search is based on reprojection. If not, diamond search is based on homography. Homography is faster than reprojection but can slightly reduce the detection rate.