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camera_calib.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<meta name="generator" content="VuePress 2.0.0-beta.38">
<style>
:root {
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html.dark {
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background-color: var(--c-bg);
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<title>Camera calibration | Clover</title><meta name="description" content="Clover Drone Kit">
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xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span><!--[--><!--]--></a></div><!--]--></nav><!--[--><!--]--><ul class="sidebar-items"><!--[--><li><a href="/clover-vuepress/en/" class="sidebar-item sidebar-heading" aria-label="COEX Clover"><!--[--><!--]--> COEX Clover <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/glossary.html" class="sidebar-item sidebar-heading" aria-label="Glossary"><!--[--><!--]--> Glossary <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/safety.html" class="sidebar-item sidebar-heading" aria-label="Safety tips"><!--[--><!--]--> Safety tips <!--[--><!--]--></a><!----></li><li><p tabindex="0" class="sidebar-item sidebar-heading collapsible">Assembly <span class="right arrow"></span></p><!--[--><ul style="display:none;" class="sidebar-item-children"><!--[--><li><a href="/clover-vuepress/en/assembly.html" class="sidebar-item" aria-label="Clover drone assembly"><!--[--><!--]--> Clover drone assembly <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/assemble_4_2.html" class="sidebar-item" aria-label="Clover 4.2 assembly"><!--[--><!--]--> Clover 4.2 assembly <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/assemble_4_2_ws.html" class="sidebar-item" aria-label="Clover 4 assembly"><!--[--><!--]--> Clover 4 assembly <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/assemble_4.html" class="sidebar-item" aria-label="Clover 4 assembly"><!--[--><!--]--> Clover 4 assembly <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/assemble_3.html" class="sidebar-item" aria-label="Assembly of Clover 3"><!--[--><!--]--> Assembly of Clover 3 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/assemble_2.html" class="sidebar-item" aria-label="Clover 2 construction kit assembly instruction"><!--[--><!--]--> Clover 2 construction kit assembly instruction <!--[--><!--]--></a><!----></li><!--]--></ul><!--]--></li><li><p tabindex="0" class="sidebar-item sidebar-heading collapsible">Configuration <span class="right arrow"></span></p><!--[--><ul style="display:none;" class="sidebar-item-children"><!--[--><li><a href="/clover-vuepress/en/setup.html" class="sidebar-item" aria-label="Initial setup"><!--[--><!--]--> Initial setup <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/calibration.html" class="sidebar-item" aria-label="Sensor calibration"><!--[--><!--]--> Sensor calibration <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/radio.html" class="sidebar-item" aria-label="RC setup"><!--[--><!--]--> RC setup <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/rc_flysky_a8s.html" class="sidebar-item" aria-label="Using Flysky FS-A8S"><!--[--><!--]--> Using Flysky FS-A8S <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/modes.html" class="sidebar-item" aria-label="Flight modes"><!--[--><!--]--> Flight modes <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/power.html" class="sidebar-item" aria-label="Power setup"><!--[--><!--]--> Power setup <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/failsafe.html" class="sidebar-item" aria-label="Failsafe configuration"><!--[--><!--]--> Failsafe configuration <!--[--><!--]--></a><!----></li><!--]--></ul><!--]--></li><li><p tabindex="0" class="sidebar-item sidebar-heading collapsible">Manual flight <span class="right arrow"></span></p><!--[--><ul style="display:none;" class="sidebar-item-children"><!--[--><li><a href="/clover-vuepress/en/flight.html" class="sidebar-item" aria-label="Flight"><!--[--><!--]--> Flight <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/flight_exercises.html" class="sidebar-item" aria-label="Drone control exercises"><!--[--><!--]--> Drone control exercises <!--[--><!--]--></a><!----></li><!--]--></ul><!--]--></li><li><p tabindex="0" class="sidebar-item sidebar-heading collapsible">Working with Raspberry Pi <span class="right arrow"></span></p><!--[--><ul style="display:none;" class="sidebar-item-children"><!--[--><li><a href="/clover-vuepress/en/raspberry.html" class="sidebar-item" aria-label="Raspberry Pi"><!--[--><!--]--> Raspberry Pi <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/image.html" class="sidebar-item" aria-label="Raspberry Pi image"><!--[--><!--]--> Raspberry Pi image <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/wifi.html" class="sidebar-item" aria-label="Connecting to Clover via Wi-Fi"><!--[--><!--]--> Connecting to Clover via Wi-Fi <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/connection.html" class="sidebar-item" aria-label="Connecting Raspberry Pi to the flight controller"><!--[--><!--]--> Connecting Raspberry Pi to the flight controller <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/gcs_bridge.html" class="sidebar-item" aria-label="Using QGroundControl via Wi-Fi"><!--[--><!--]--> Using QGroundControl via Wi-Fi <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/ssh.html" class="sidebar-item" aria-label="SSH access to Raspberry Pi"><!--[--><!--]--> SSH access to Raspberry Pi <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/cli.html" class="sidebar-item" aria-label="Command line interface"><!--[--><!--]--> Command line interface <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/selfcheck.html" class="sidebar-item" aria-label="Automatic check"><!--[--><!--]--> Automatic check <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/web_video_server.html" class="sidebar-item" aria-label="Viewing images from cameras"><!--[--><!--]--> Viewing images from cameras <!--[--><!--]--></a><!----></li><!--]--></ul><!--]--></li><li><p tabindex="0" class="sidebar-item sidebar-heading collapsible">Programming <span class="right arrow"></span></p><!--[--><ul style="display:none;" class="sidebar-item-children"><!--[--><li><a href="/clover-vuepress/en/programming.html" class="sidebar-item" aria-label="Programming"><!--[--><!--]--> Programming <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/camera_setup.html" class="sidebar-item" aria-label="Camera setup"><!--[--><!--]--> Camera setup <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/aruco.html" class="sidebar-item" aria-label="ArUco markers"><!--[--><!--]--> ArUco markers <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/aruco_marker.html" class="sidebar-item" aria-label="ArUco marker detection"><!--[--><!--]--> ArUco marker detection <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/aruco_map.html" class="sidebar-item" aria-label="Map-based navigation with ArUco markers"><!--[--><!--]--> Map-based navigation with ArUco markers <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/optical_flow.html" class="sidebar-item" aria-label="Use of Optical Flow"><!--[--><!--]--> Use of Optical Flow <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/simple_offboard.html" class="sidebar-item" aria-label="Autonomous flight"><!--[--><!--]--> Autonomous flight <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/frames.html" class="sidebar-item" aria-label="Coordinate systems (frames)"><!--[--><!--]--> Coordinate systems (frames) <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/snippets.html" class="sidebar-item" aria-label="Code examples"><!--[--><!--]--> Code examples <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/laser.html" class="sidebar-item" aria-label="Working with a laser rangefinder"><!--[--><!--]--> Working with a laser rangefinder <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/leds.html" class="sidebar-item" aria-label="Working with a LED strip"><!--[--><!--]--> Working with a LED strip <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/gpio.html" class="sidebar-item" aria-label="Working with GPIO"><!--[--><!--]--> Working with GPIO <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/sonar.html" class="sidebar-item" aria-label="Working with the ultrasonic distance gage"><!--[--><!--]--> Working with the ultrasonic distance gage <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/camera.html" class="sidebar-item" aria-label="Working with the camera"><!--[--><!--]--> Working with the camera <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/rviz.html" class="sidebar-item" aria-label="Using rviz and rqt"><!--[--><!--]--> Using rviz and rqt <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/autolaunch.html" class="sidebar-item" aria-label="Software autorun"><!--[--><!--]--> Software autorun <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/javascript.html" class="sidebar-item" aria-label="Work with ROS from browser"><!--[--><!--]--> Work with ROS from browser <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/blocks.html" class="sidebar-item" aria-label="Blocks programming for Clover"><!--[--><!--]--> Blocks programming for Clover <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/simulation.html" class="sidebar-item" aria-label="Simulation overview"><!--[--><!--]--> Simulation overview <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/simulation_native.html" class="sidebar-item" aria-label="Native setup"><!--[--><!--]--> Native setup <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/simulation_vm.html" class="sidebar-item" aria-label="Simulation VM setup"><!--[--><!--]--> Simulation VM setup <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/simulation_usage.html" class="sidebar-item" aria-label="Using the simulator"><!--[--><!--]--> Using the simulator <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/simulation_m1.html" class="sidebar-item" aria-label="Running simulator on M1 powered computer"><!--[--><!--]--> Running simulator on M1 powered computer <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/ros.html" class="sidebar-item" aria-label="ROS"><!--[--><!--]--> ROS <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/mavros.html" class="sidebar-item" aria-label="MAVROS"><!--[--><!--]--> MAVROS <!--[--><!--]--></a><!----></li><!--]--></ul><!--]--></li><li><p tabindex="0" class="sidebar-item sidebar-heading collapsible">Supplementary materials <span class="right arrow"></span></p><!--[--><ul style="display:none;" class="sidebar-item-children"><!--[--><li><a href="/clover-vuepress/en/supplementary.html" class="sidebar-item" aria-label="Supplementary materials"><!--[--><!--]--> Supplementary materials <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/coex_pix.html" class="sidebar-item" aria-label="COEX Pix"><!--[--><!--]--> COEX Pix <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/coex_pdb.html" class="sidebar-item" aria-label="COEX PDB"><!--[--><!--]--> COEX PDB <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/coex_gps.html" class="sidebar-item" aria-label="COEX GPS"><!--[--><!--]--> COEX GPS <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/auto_setup.html" class="sidebar-item" aria-label="Step-by-step guide on autonomous flight with Clover 4"><!--[--><!--]--> Step-by-step guide on autonomous flight with Clover 4 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/hostname.html" class="sidebar-item" aria-label="Hostname"><!--[--><!--]--> Hostname <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/sitl.html" class="sidebar-item" aria-label="PX4 Simulation"><!--[--><!--]--> PX4 Simulation <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/wall_aruco.html" class="sidebar-item" aria-label="Navigation using vertical ArUco-markers"><!--[--><!--]--> Navigation using vertical ArUco-markers <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/calibratePID.html" class="sidebar-item" aria-label="Configuring the PID coefficients"><!--[--><!--]--> Configuring the PID coefficients <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/models.html" class="sidebar-item" aria-label="Model files for parts"><!--[--><!--]--> Model files for parts <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/ros-install.html" class="sidebar-item" aria-label="ROS Melodic package installation and setup"><!--[--><!--]--> ROS Melodic package installation and setup <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/camera_calibration.html" class="sidebar-item" aria-label="Camera calibration"><!--[--><!--]--> Camera calibration <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/zerotire_vpn.html" class="sidebar-item" aria-label="Creating a virtual network ZeroTier One and connecting to it"><!--[--><!--]--> Creating a virtual network ZeroTier One and connecting to it <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/4g.html" class="sidebar-item" aria-label="Multi-copter control with 4G communication"><!--[--><!--]--> Multi-copter control with 4G communication <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/jetson_nano.html" class="sidebar-item" aria-label="Clover and Jetson Nano"><!--[--><!--]--> Clover and Jetson Nano <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/rc.html" class="sidebar-item" aria-label="Controlling Clover from a smartphone"><!--[--><!--]--> Controlling Clover from a smartphone <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/network.html" class="sidebar-item" aria-label="Configuring Wi-Fi"><!--[--><!--]--> Configuring Wi-Fi <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/uart.html" class="sidebar-item" aria-label="UART interface"><!--[--><!--]--> UART interface <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/parameters.html" class="sidebar-item" aria-label="PX4 Parameters"><!--[--><!--]--> PX4 Parameters <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/flight_logs.html" class="sidebar-item" aria-label="PX4 Logs and Topics"><!--[--><!--]--> PX4 Logs and Topics <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/firmware.html" class="sidebar-item" aria-label="Pixhawk / Pixracer firmware flashing"><!--[--><!--]--> Pixhawk / Pixracer firmware flashing <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/mavlink.html" class="sidebar-item" aria-label="MAVLink"><!--[--><!--]--> MAVLink <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/test_connection.html" class="sidebar-item" aria-label="How to use a multimeter?"><!--[--><!--]--> How to use a multimeter? <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/radioerrors.html" class="sidebar-item" aria-label="Possible radio failures"><!--[--><!--]--> Possible radio failures <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/esc_firmware.html" class="sidebar-item" aria-label="Flashing ESCs using BLHeliSuite"><!--[--><!--]--> Flashing ESCs using BLHeliSuite <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/arduino.html" class="sidebar-item" aria-label="Controlling the copter from Arduino"><!--[--><!--]--> Controlling the copter from Arduino <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/gps.html" class="sidebar-item" aria-label="Connecting GPS"><!--[--><!--]--> Connecting GPS <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/ir_sensors.html" class="sidebar-item" aria-label="Working with IR sensors on Raspberry Pi 3"><!--[--><!--]--> Working with IR sensors on Raspberry Pi 3 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/fpv_clover_4_2.html" class="sidebar-item" aria-label="Installing and configuring FPV equipment"><!--[--><!--]--> Installing and configuring FPV equipment <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/fpv.html" class="sidebar-item" aria-label="Installation of FPV"><!--[--><!--]--> Installation of FPV <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/magnetic_grip.html" class="sidebar-item" aria-label="Assembling and setting up the electromagnetic gripper"><!--[--><!--]--> Assembling and setting up the electromagnetic gripper <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/mechanical_grip.html" class="sidebar-item" aria-label="Assembling and setting up a mechanical gripper"><!--[--><!--]--> Assembling and setting up a mechanical gripper <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/trainer_mode.html" class="sidebar-item" aria-label="FlySky Trainer mode settings"><!--[--><!--]--> FlySky Trainer mode settings <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/tinning.html" class="sidebar-item" aria-label="Blanching"><!--[--><!--]--> Blanching <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/connectortypes.html" class="sidebar-item" aria-label="Types of power connectors"><!--[--><!--]--> Types of power connectors <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/4in1.html" class="sidebar-item" aria-label="Connecting 4 in 1 ESCs"><!--[--><!--]--> Connecting 4 in 1 ESCs <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/tb.html" class="sidebar-item" aria-label="Soldering safety"><!--[--><!--]--> Soldering safety <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/leds_old.html" class="sidebar-item" aria-label="Working with a LED strip on Raspberry 3"><!--[--><!--]--> Working with a LED strip on Raspberry 3 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/contributing.html" class="sidebar-item" aria-label="Contribution to Clover"><!--[--><!--]--> Contribution to Clover <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/packages.html" class="sidebar-item" aria-label="COEX packages repository"><!--[--><!--]--> COEX packages repository <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/migrate20.html" class="sidebar-item" aria-label="Migration to version 0.20"><!--[--><!--]--> Migration to version 0.20 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/migrate22.html" class="sidebar-item" aria-label="Migration to version 0.22"><!--[--><!--]--> Migration to version 0.22 <!--[--><!--]--></a><!----></li><!--]--></ul><!--]--></li><li><p tabindex="0" class="sidebar-item sidebar-heading collapsible">Events <span class="right arrow"></span></p><!--[--><ul style="display:none;" class="sidebar-item-children"><!--[--><li><a href="/clover-vuepress/en/events.html" class="sidebar-item" aria-label="Events"><!--[--><!--]--> Events <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/copterhack2022.html" class="sidebar-item" aria-label="CopterHack 2022"><!--[--><!--]--> CopterHack 2022 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/copterhack2021.html" class="sidebar-item" aria-label="CopterHack 2021"><!--[--><!--]--> CopterHack 2021 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/copterhack2019.html" class="sidebar-item" aria-label="Copter Hack 2019"><!--[--><!--]--> Copter Hack 2019 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/copterhack2018.html" class="sidebar-item" aria-label="Copter Hack 2018"><!--[--><!--]--> Copter Hack 2018 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/copterhack2017.html" class="sidebar-item" aria-label="Copter Hack 2017"><!--[--><!--]--> Copter Hack 2017 <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/video_contest.html" class="sidebar-item" aria-label="Contest for the best educational video on assembly and configuration"><!--[--><!--]--> Contest for the best educational video on assembly and configuration <!--[--><!--]--></a><!----></li><li><a href="/clover-vuepress/en/educational_contests.html" class="sidebar-item" aria-label="Educational contests"><!--[--><!--]--> Educational contests <!--[--><!--]--></a><!----></li><!--]--></ul><!--]--></li><!--]--></ul><!--[--><!--]--></aside><!--]--><!--[--><main class="page"><!--[--><!--]--><div class="theme-default-content"><!--[--><h1 id="camera-calibration" tabindex="-1"><a class="header-anchor" href="#camera-calibration" aria-hidden="true">#</a> Camera calibration</h1><p>Computer vision is becoming more and more widespread. Often, computer vision algorithms are not precise and obtain distorted images from the camera, which is especially true for fisheye cameras.</p><p><img src="/clover-vuepress/assets/img1.289a831b.jpg" alt="img"></p><blockquote><p>The image is "rounded" closer to the edge.</p></blockquote><p>Any computer vision algorithm will perceive the picture incorrectly. To remove such distortion, the camera that receives the image is to be calibrated in accordance with its own peculiarities.</p><h2 id="script-installation" tabindex="-1"><a class="header-anchor" href="#script-installation" aria-hidden="true">#</a> Script installation</h2><p>First, you have to install the necessary libraries:</p><div class="language-text ext-text"><pre class="language-text"><code>pip install numpy
pip install opencv-python
pip install glob
pip install pyyaml
pip install urllib.request
</code></pre></div><p>Then download the script from the repository:</p><div class="language-text ext-text"><pre class="language-text"><code>git clone https://github.com/tinderad/clever_cam_calibration.git
</code></pre></div><p>Go to the downloaded folder and install the script:</p><div class="language-text ext-text"><pre class="language-text"><code>cd clever_cam_calibration
sudo python setup.py build
sudo python setup.py install
</code></pre></div><p>If you are using Windows, download the archive from the <a href="https://github.com/tinderad/clever_cam_calibration/archive/master.zip" target="_blank" rel="noopener noreferrer">repository<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span></a>, unzip it and install:</p><div class="language-text ext-text"><pre class="language-text"><code>cd path\to\archive\clever_cam_calibration\
python setup.py build
python setup.py install
</code></pre></div><blockquote><p>path\to\archive – path to unpacked archive.</p></blockquote><h2 id="preparing-for-calibration" tabindex="-1"><a class="header-anchor" href="#preparing-for-calibration" aria-hidden="true">#</a> Preparing for calibration</h2><p>You will have to prepare a calibration target. It looks like a chessboard. The file is available for downloading <a href="https://www.oreilly.com/library/view/learning-opencv-3/9781491937983/assets/lcv3_ac01.png" target="_blank" rel="noopener noreferrer">here<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span></a>. Glue a printed target to any solid surface. Count the number of intersections on the board lengthwise and widthwise, measure the size of a cell (mm).</p><p><img src="/clover-vuepress/assets/chessboard.cba2e2e5.jpg" alt="img"></p><p>Turn on Clover and connect to its Wi-Fi.</p><blockquote><p>Navigate to 192.168.11.1:8080 and check whether the computer receives images from the image_raw topic.</p></blockquote><h2 id="calibration" tabindex="-1"><a class="header-anchor" href="#calibration" aria-hidden="true">#</a> Calibration</h2><p>Run script <em><strong>calibrate_cam</strong></em>:</p><p><strong>Windows:</strong></p><div class="language-text ext-text"><pre class="language-text"><code>>path\to\python\Scripts\calibrate_cam.exe
</code></pre></div><blockquote><p>path\to\Python – path to the Python folder</p></blockquote><p><strong>Linux:</strong></p><div class="language-text ext-text"><pre class="language-text"><code>>calibrate_cam
</code></pre></div><p>Specify board parameters:</p><div class="language-text ext-text"><pre class="language-text"><code>>calibrate_cam
Chessboard width: # Intersections widthwise
Chessboard height: # Intersections heightwise
Square size: # Length of cell edge (mm)
Saving mode (YES - on): # Save mode
</code></pre></div><blockquote><p>Save mode: if enabled, all received pictures will be saved in the current folder.</p></blockquote><p>The script will start running:</p><div class="language-text ext-text"><pre class="language-text"><code>Calibration started!
Commands:
help, catch (key: Enter), delete, restart, stop, finish
</code></pre></div><p>To calibrate the camera, make at least 25 photos of the chessboard at various angles.</p><p><img src="/clover-vuepress/assets/calibration.8c5782f4.jpg" alt="img"></p><p>To make a photo, enter command <em><strong>catch</strong></em>.</p><div class="language-text ext-text"><pre class="language-text"><code>>catch
</code></pre></div><p>The program will inform you about the calibration status.</p><div class="language-text ext-text"><pre class="language-text"><code>...
Chessboard not found, now 0 (25 required)
> # Enter
---
Image added, now 1 (25 required)
</code></pre></div><blockquote><p>Instead of entering command <em><strong>catch</strong></em> each time, you can just press <em><strong>Enter</strong></em> (enter a blank line).</p></blockquote><p>After you have made a sufficient number of images, enter command <em><strong>finish</strong></em>.</p><div class="language-text ext-text"><pre class="language-text"><code>...
>finish
Calibration successful!
</code></pre></div><h3 id="calibration-by-the-existing-images" tabindex="-1"><a class="header-anchor" href="#calibration-by-the-existing-images" aria-hidden="true">#</a> Calibration by the existing images</h3><p>If you already have images, you can calibrate the camera by them with the help of script <em><strong>calibrate_cam_ex</strong></em>.</p><div class="language-text ext-text"><pre class="language-text"><code>>calibrate_cam_ex
</code></pre></div><p>Specify target characteristics and the path to the folder with images:</p><div class="language-text ext-text"><pre class="language-text"><code>>calibrate_cam_ex
Chessboard width: # Intersections widthwise
Chessboard height: # Intersections heightwise
Square size: # Length of cell edge (mm)
Path: # Path to the folder with images
</code></pre></div><p>Apart from that, this script works similarly to <em><strong>calibrate_cam</strong></em>.</p><p>The program will process all received pictures, and create file <em><strong>camera_info.yaml</strong></em> in the current folder. Using this file, you can equalize distortions in the images obtained from this camera.</p><blockquote><p>If you change the resolution of the received image, you will have to re-calibrate the camera.</p></blockquote><h2 id="correcting-distortions" tabindex="-1"><a class="header-anchor" href="#correcting-distortions" aria-hidden="true">#</a> Correcting distortions</h2><p>Function <em><strong>get_undistorted_image(cv2_image, camera_info)</strong></em> is responsible for obtaining a corrected image:</p><ul><li><em><strong>cv2_image</strong></em>: An image encoded into a cv2 array.</li><li><em><strong>camera_info</strong></em>: The path to the calibration file.¬</li></ul><p>The function returns a cv2 array, into which the corrected image is coded.</p><blockquote><p>If you are using a fisheye camera provided with Clover, for processing images with resolution 320x240 or 640x480, you can use the existing calibration settings. To do this, pass parameters <em><strong>clever_cam_calibration.clevercamcalib.CLEVER_FISHEYE_CAM_320</strong></em> or <em><strong>clever_cam_calibration.clevercamcalib.CLEVER_FISHEYE_CAM_640</strong></em> as argument <em><strong>camera_info</strong></em>, respectively.</p></blockquote><h2 id="examples-of-operation" tabindex="-1"><a class="header-anchor" href="#examples-of-operation" aria-hidden="true">#</a> Examples of operation</h2><p>Source images:</p><p><img src="/clover-vuepress/assets/img1.289a831b.jpg" alt="img"></p><p><img src="/clover-vuepress/assets/img2.d9937e8e.jpg" alt="img"></p><p>Corrected images:</p><p><img src="/clover-vuepress/assets/calibresult.9662f3a2.jpg" alt="img"></p><p><img src="/clover-vuepress/assets/calibresult1.d3a271e0.jpg" alt="img"></p><h2 id="an-example-of-usage" tabindex="-1"><a class="header-anchor" href="#an-example-of-usage" aria-hidden="true">#</a> An example of usage</h2><p><strong>Processing image stream from the camera</strong>.</p><p>This program receives images from the camera on Clover and displays them on the screen in corrected for, using the existing calibration file.</p><div class="language-python ext-py"><pre class="language-python"><code><span class="token keyword">import</span> clevercamcalib<span class="token punctuation">.</span>clevercamcalib <span class="token keyword">as</span> ccc
<span class="token keyword">import</span> cv2
<span class="token keyword">import</span> urllib<span class="token punctuation">.</span>request
<span class="token keyword">import</span> numpy <span class="token keyword">as</span> np
<span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span>
req <span class="token operator">=</span> urllib<span class="token punctuation">.</span>request<span class="token punctuation">.</span>urlopen<span class="token punctuation">(</span><span class="token string">'http://192.168.11.1:8080/snapshot?topic=/main_camera/image_raw'</span><span class="token punctuation">)</span>
arr <span class="token operator">=</span> np<span class="token punctuation">.</span>asarray<span class="token punctuation">(</span><span class="token builtin">bytearray</span><span class="token punctuation">(</span>req<span class="token punctuation">.</span>read<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">,</span> dtype<span class="token operator">=</span>np<span class="token punctuation">.</span>uint8<span class="token punctuation">)</span>
image <span class="token operator">=</span> cv2<span class="token punctuation">.</span>imdecode<span class="token punctuation">(</span>arr<span class="token punctuation">,</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span>
undistorted_img <span class="token operator">=</span> ccc<span class="token punctuation">.</span>get_undistorted_image<span class="token punctuation">(</span>image<span class="token punctuation">,</span> ccc<span class="token punctuation">.</span>CLEVER_FISHEYE_CAM_640<span class="token punctuation">)</span>
cv2<span class="token punctuation">.</span>imshow<span class="token punctuation">(</span><span class="token string">"undistort"</span><span class="token punctuation">,</span> undistorted_img<span class="token punctuation">)</span>
cv2<span class="token punctuation">.</span>waitKey<span class="token punctuation">(</span><span class="token number">33</span><span class="token punctuation">)</span>
cv2<span class="token punctuation">.</span>destroyAllWindows<span class="token punctuation">(</span><span class="token punctuation">)</span>
</code></pre></div><h2 id="the-usage-for-aruco" tabindex="-1"><a class="header-anchor" href="#the-usage-for-aruco" aria-hidden="true">#</a> The usage for ArUco</h2><p>To apply the calibration parameters to the ArUco navigation system, move the calibration .yaml file to Raspberry Pi of Clover, and initialize it.</p><blockquote><p>Don't forget to connect to Wi-Fi of Clover.</p></blockquote><p>The SFTP protocol is used for transferring the file. This example, WinSCP program is used.</p><p>Connect to Raspberry Pi via SFTP:</p><blockquote><p>Password: <em><strong>raspberry</strong></em></p></blockquote><p><img src="/clover-vuepress/assets/wcp1.ee7a6036.png" alt="img"></p><p>Press “Enter”. Go to <em><strong>/home/pi/catkin_ws/src/clever/clever/camera_info/</strong></em>, and copy the calibration .yaml file to this folder:</p><p><img src="/clover-vuepress/assets/wcp2.a9e43008.jpg" alt="img"></p><p>Now we have to select this file in ArUco configuration. Connection via SSH is used for this purpose. This example, PuTTY program is used.</p><p>Connect to Raspberry Pi via SSH:</p><p><img src="/clover-vuepress/assets/pty1.6b9af9bf.jpg" alt="img"></p><p>Log in with username <em><strong>pi</strong></em> and password <em><strong>raspberry</strong></em>, go to directory <em><strong>/home/pi/catkin_ws/src/clever/clever/launch</strong></em> and start editing configuration <em><strong>main_camera.launch</strong></em>:</p><p><img src="/clover-vuepress/assets/pty2.bf788457.jpg" alt="img"></p><p>In line <em><strong>camera node</strong></em>, change parameter <em><strong>camera_info</strong></em> to <em><strong>camera_info.yaml</strong></em>:</p><p><img src="/clover-vuepress/assets/pty3.2a56c576.jpg" alt="img"></p><blockquote><p>Don't forget to change camera resolution.</p></blockquote><!--]--></div><footer class="page-meta"><div class="meta-item edit-link"><a class="external-link meta-item-label" href="https://github.com/CopterExpress/clover/edit/master/docs/en/camera_calib.md" rel="noopener noreferrer" target="_blank" aria-label="Edit this page"><!--[--><!--]--> Edit this page <span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span><!--[--><!--]--></a></div><!----><!----></footer><!----><!--[--><!--]--></main><!--]--></div><!----><!--]--></div>
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