Camera calibration (USB)

1. Start the camera

cd ~/yahboom_ws

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source install/setup.bash

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ros2 run camera camera_usb

2. Image calibration

2.1. Calibration board

2.2. View topics

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ros2 topic list

2.3. Image calibration

2.3.1. Install the image calibration tool

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sudo apt update
sudo apt install ros-humble-image-pipeline -y

2.3.2. Start the image calibration tool

Start the ROS2 camera calibration tool camera_calibration and perform camera calibration: Before calibration, you need to start the camera first

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ros2 run camera_calibration cameracalibrator --size 9x6 --square 0.02 --ros-args --remap /image:=/image_raw

Parameter Description

--size：The number of inner corner points of the chessboard → 9 rows and 6 columns of inner corner points

--square：The side length of the chessboard → 0.02 meters

--ros-args：Passing ROS parameters

--remap：Topic remapping → /image_raw as image input stream

2.3.3 Calibration process

Parameter Description

X：The chessboard moves left and right in the camera's field of view

Y：The chessboard moves up and down in the camera's field of view

Size：The chessboard moves back and forth in the camera's field of view

Skew：Tilt and rotate of the chessboard in the camera's field of view

When X, Y, Size, and Skew turn green, you can click CALIBRATE to calculate the camera internal parameters: The more pictures you calibrate, the longer it takes, and the program may get stuck.

After calibration, click SAVE to save the results!

Close the program after successful saving!

2.3.4, Calibration results

Default save location and file name of calibration results:

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/tmp/calibrationdata.tar.gz

Copy and decompress the calibration results:

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sudo mv /tmp/calibrationdata.tar.gz ~
mkdir calibrationdata
tar -xzvf calibrationdata.tar.gz -C ~/calibrationdata

The decompressed files contain the calibration *.png, ost.yaml and ost.txt files. We mainly copy the data in the ost.yaml file to the camera_usb.yaml file.

ost.yaml

Replace the camera_usb.yaml file data with the image_width, image_height, data in camera_matrix, data in projection_matrix, and data in distortion_coefficients.

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image_width: 1280
image_height: 800
camera_name: narrow_stereo
camera_matrix:
  rows: 3
  cols: 3
  data: [2126.24686,    0.     , 1045.90416,
            0.     , 2038.73134,  292.1827 ,
            0.     ,    0.     ,    1.     ]
distortion_model: plumb_bob
distortion_coefficients:
  rows: 1
  cols: 5
  data: [0.618718, -0.496057, -0.038096, 0.134905, 0.000000]
rectification_matrix:
  rows: 3
  cols: 3
  data: [1., 0., 0.,
         0., 1., 0.,
         0., 0., 1.]
projection_matrix:
  rows: 3
  cols: 4
  data: [2049.23772,    0.     , 1082.02717,    0.     ,
            0.     , 2153.52835,  282.33049,    0.     ,
            0.     ,    0.     ,    1.     ,    0.     ]

camera_csi.yaml

Modified file:

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%YAML:1.0
---
image_width: 1920
image_height: 1080
camera_name: camera
camera_matrix: !!opencv-matrix
  rows: 3
  cols: 3
  dt: d
  data: [2126.24686,    0.     , 1045.90416,
            0.     , 2038.73134,  292.1827 ,
            0.     ,    0.     ,    1.     ]
distortion_model: plumb_bob
distortion_coefficients: !!opencv-matrix
  rows: 1
  cols: 5
  dt: d
  data: [0.618718, -0.496057, -0.038096, 0.134905, 0.000000]
rectification_matrix:
  rows: 3
  cols: 3
  data: [1., 0., 0.,
         0., 1., 0.,
         0., 0., 1.]
projection_matrix:
  rows: 3
  cols: 4
  data: [2049.23772,    0.     , 1082.02717,    0.     ,
            0.     , 2153.52835,  282.33049,    0.     ,
            0.     ,    0.     ,    1.     ,    0.     ]