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Note: I don't actively maintain this repository anymore. PRs are more than welcome to help improve it.

This repository contains some sources to calibrate the intrinsics of individual cameras and also the extrinsics of a stereo pair.

• OpenCV
• popt

Compile all the files using the following commands.

mkdir build&&cd buildcmake ..make

Make sure your are in thebuild folder to run the executables.

This is a small helper tool to grab frames from two webcams operating as a stereo pair. Run the following command to use it.

./read -w [img_width] -h [img_height] -d [imgs_directory] -e [file_extension]

Once it is running, hit any key to grab frames. Images are saved with prefixesleft andright in the desired directory.

This is only for lenses which follow the pinhole model. If you have fisheye lenses with a very wide field of view then seethis repository. The calibration saves the camera matrix and the distortion coefficients in a YAML file. The datatype for these matrices isMat.

Once you have compiled the sources run the following command to calibrate the intrinsics.

./calibrate -w [board_width] -h [board_height] -n [num_imgs] -s [square_size] -d [imgs_directory] -i [imgs_filename] -e [file_extension] -o [output_filename]

For example, the command for the test images incalib_imgs/1/ would be

./calibrate -w 9 -h 6 -n 27 -s 0.02423 -d"../calib_imgs/1/" -i"left" -o"cam_left.yml" -e"jpg"

Once you have the intrinsics calibrated for both the left and the right cameras, you can use their intrinsics to calibrate the extrinsics between them.

./calibrate_stereo -n [num_imgs] -u [left_cam_calib] -v [right_cam_calib] -L [left_img_dir] -R [right_img_dir] -l [left_img_prefix] -r [right_img_prefix] -o [output_calib_file] -e [file_extension]

For example, if you calibrated the left and the right cameras using the images in thecalib_imgs/1/ directory, the following command to compute the extrinsics.

./calibrate_stereo -n 27 -u cam_left.yml -v cam_right.yml -L ../calib_imgs/1/ -R ../calib_imgs/1/ -l left -r right -o cam_stereo.yml -e jpg

Once you have the stereo calibration data, you can remove the distortion and rectify any pair of images so that the resultant epipolar lines become scan lines.

./undistort_rectify -l [left_img_path] -r [right_img_path] -c [stereo_calib_file] -L [output_left_img] -R [output_right_img]

For example

./undistort_rectify -l ../calib_imgs/1/left1.jpg -r ../calib_imgs/1/right1.jpg -c cam_stereo.yml -L left.jpg -R right.jpg