Find Calibration Chessboard in Image

findChessboardCorners finds the positions of the internal corners of a calibration chessboard.

Usage

findChessboardCorners(
  image,
  pprow,
  ppcol,
  adaptive_threshold = TRUE,
  normalize = TRUE,
  filter_quads = FALSE,
  fast_check = TRUE
)

Arguments

image

An 8-bit (8U) Image object.

pprow, ppcol

The number of internal corners per row and column of the chessboard.

adaptive_threshold

A logical indicating whether to use adaptive thresholding (the default) to convert the image to black and white, rather than a fixed threshold level (computed from the average image brightness).

normalize

A logical indicating whether to normalize (the default) the image gamma with histEq before applying fixed or adaptive thresholding.

filter_quads

A logical indicating whether to use additional criteria (like contour area, perimeter, square-like shape) to filter out false quads extracted at the contour retrieval stage (default: FALSE).

fast_check

logical indicating whether to run a fast check on the image that looks for chessboard corners, and shortcut the call if none is found. This can drastically speed up the call in the degenerate condition when no chessboard is observed.

Value

A (pprow * ppcol)x2 matrix. If the matrix is empty then no chessboard with the indicated dimensions is detected.

Note

You can find a suitable chessboard pattern at https://github.com/opencv/opencv/blob/4.x/doc/pattern.png

See also

cornerSubPix, calibrateCamera

Author

Simon Garnier, garnier@njit.edu

Examples

checkerboard <- image(system.file("sample_img/checkerboard6x9.png", package = "Rvision"))
pts <- findChessboardCorners(checkerboard, 6, 9)