We now offer Kalibr calibration targets on Dibond with an Anti-Reflective surface "flood white" print option for a true matte finish, making them more easily detected in your computer vision pipeline.
Are you looking to pre-calibrate your camera parameters with a calibration target to be as accurate as possible? Our Kalibr Targets are printed directly onto a rigid on premium 1/8 inch Dibond, making them the perfect calibration boards to calibrate cameras.
Direct to substrate printing at 1000 dpi with anti-reflective surface "flood white" authentic matte finish allows for easy detection in your computer vision pipeline because of its optical performance and physical robustness.
Dibond signage has forever been an industry standard for indoor and outdoor business signs. The material is water, weather, warp resistant and rust proof. It's ultra flat and rigid structure makes Dibond the perfect material for calibration target.
Picture source: https://pixabay.com/photos/lens-camera-photography-3114729/
Kalibr refers to a toolbox that solves various problems, including:
Kalibr uses the calibration software, and it is ideal for IMU and multi-camera calibration.
The calibrations are based on the AprilTag coded markers. They enable the recording of information from the edges of the images, which helps in the robust and accurate lens parameters' determination.
The coding of feature points also helps in stereo calibration in which corners can be partly non-visible.
Additionally, the software comes with advanced calibration routines that are ideal for autonomous vehicle calibration and drones.
They support three targets which include:
Aprilgrid is the most preferred one as it comes with many benefits, including:
You'll use the YAML configuration files offered to the calibration software to configure the targets.
Aprilgrid is the recommended choice as it simplifies data collection significantly.
With Aprilgrid, the targets are partially visible, and you can detect them without a challenge.
You can download Aprilgrids from the download page, or you can also create the custom grids.
When collecting the calibration data sets, you should make sure to hide all external Apriltags.
The software uses the Apriltag implementation of M. Kaess for tag extraction.
Most calibration targets have an aluminum or LDPE composite construction, which offers a perfect stiffness and flatness but is also lightweight.
Additionally, the composite material is corrosion-resistant, and it also offers good thermal stability.
You use the direct UV (Ultra-Violet) printing process to transfer the patterns to the composite material. This results in a durable matte finish.
The ultra-violet printing process is ideal for machine vision applications where you require accuracy, excellent optical performance, and physical robustness.
Circle grids are also a common and famous calibration target design based on circles. It can be white circles on a dark background or dark/black circles on a white background.
If you are using image processing terms, you can detect circles as blobs in the image. You can apply simple conditions on the binary blob regions such as convexity, area, circularity, etc., to get rid of bad feature candidates.
After getting the best candidates, you use the regular structure of features to identify and filter the pattern. You can enjoy high accuracy in the determination of circles as you can use all the pixels in the periphery of circles, which decreases the influence of image noise.
These targets are based on the traditional checkerboards, and they can use the same algorithms.
They have three circles at the center, enabling absolute referencing even with partial views of the checkerboard.
There are two sources available for the toolbox, including:
It is the fastest way to have the toolbox running. You get all dependencies on the package, and you don't require external dependencies. The CDE package doesn't include a calibration validator or camera focus as they require ROS installation.
The source depends on the installation of catkin workspace and ROS indigo. All tools are available with this source, and it runs faster than the CDE package.
CDE package is an excellent option if you wish to remove the need for installing ROS.
Ensure you install the most recent package. You can run the tools from the CDE package folder directly.
To use the building from the source option, first, ensure you install the ROS indigo.
Example installation on Ubuntu includes:
sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu trusty main" > /etc/apt/sources.list.d/ros-latest.list'
After that, install the dependencies and come up with a catkin workspace.
Clone the source repo into the catkin workspace src folder and then use the Release configuration to build the code.
You can also use the Docker image by Stereo labs to run the software.
You can check the image topic Hz by running the camera using the following command:
roslaunch realsense2_camera rs_camera . launch
rostopic Hz / camera/color/image_raw
Kalibr is one type of calibration software (others being PhotoModeler and Halcon) that is ideal for solving various challenges, including rolling shutter camera calibration, visual-inertia calibration, and multiple-camera calibration.
It is great! The team members really know what they are doing and are very helpful. Nice experience! And nice printing!
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