Calibration Target Printing

Kalibr Targets

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.

  • 0.125
x
  • Flood White $22.78
  • 1/2" All Corners $2.00 ea.
  • 1/4" All Corners $2.00 ea.
  • 3/8" All Corners $2.00 ea.
  • Special $11.39

Kalibr Targets

Are you looking to pre-calibrate your camera 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 Features

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 targets.

  • Light weight
  • Ultra flat surface
  • Anti-reflective surface (flood white finish) pitch black on pure white
  • Rigid and sturdy
  • Water, weather & rust proof

Technical Specifications

  • Material Thickness: .125"
  • Panel Type: Aluminium Composite Panel
  • Temperature Range: from -50°C to +80°C
  • Fire Classification: CLASS P/0/1
  • Physical Weight: 0.78125 lbs per ft.²

Helpful Ordering Tips

  1. Order the exact sizes that match your file's artboards; use the keyboard to add decimals if needed.
  2. Upload your own custom files, vector PDF files are preferred for optimal print results.
  3. Full-scale files are required to avoid the files being scaled up or down to fit the image on the board's order size.
  4. During the proofing process, always double-check and compare the file size to each board order size (Foamcoreprint.com is not responsible for artwork scaling if the incorrect board sizes are ordered and proofs are approved incorrectly).
  5. If you have questions about the artwork uploaded to an order; please call, email, or start a live chat before sending the art files to print. Production will begin within 10 mins of approval of artwork. Once production begins, we can not remove approved art files from the production line.

Kalibr Targets | Ideal for IMU and Multi-Camera Calibration

Kalibr refers to a toolbox that solves various problems, including:

  • Multiple camera calibration: multiple camera calibration refers to the intrinsic and extrinsic calibrations of a camera system with overlapping fields of view
  • Rolling shutter camera calibration: this involves full intrinsic calibration of rolling shutter cameras. The full intrinsic calibration includes projection, distortion, and the shutter parameters
  • Visual-inertial calibration (Camera-IMU): visual-inertial calibration refers to the spatial and temporal calibration of an IMU w.r.t camera system

Calibration Software

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.

Calibration Targets

They support three targets which include:

Aprilgrid is the most preferred one as it comes with many benefits, including:

  • You can use the partially visible calibration boards
  • The pose of the target is fully resolved (no flips)

You'll use the YAML configuration files offered to the calibration software to configure the targets.

Aprilgrid

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.

Circlegrids

Circle grids are also a common and famous 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.

Checkerboard Marker Targets

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.

Tips on Using the Targets

  • You should ensure the calibration target is as flat as possible. It will be best to glue it to a rigid plate such as acrylic glass or aluminum
  • It will be best to have a white border around the calibration target, or you will have challenges with detection in various lighting conditions
  • Various printers will scale the target while printing. As such, it will be best to remeasure all the essential sizes and also adjust the target configuration

Kalibr Targets Installation

There are two sources available for the toolbox, including:

CDE Package

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.

Building From Source

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.

Using 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.

Building From Source

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.

Using Through Docker

You can also use the Docker image by Stereo labs to run the software.

Check Image Topic Hz

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

Conclusion

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.

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8 days ago by Yaoyu Hu (PA, US)

It is great! The team members really know what they are doing and are very helpful. Nice experience! And nice printing!