Calibration Object

핸드-아이 칼리브레이션 프로세스에는 카메라 이미지에서 감지 및 위치화할 수 있는 알려진 기하학적 개체를 사용해야 합니다. 2D 패턴은 칼리브레이션 대상으로 가장 일반적으로 사용됩니다. OpenCV 라이브러리는 체커보드을 사용하는 반면 HALCON 소프트웨어는 도트(점) 패턴을 사용합니다. 3D 카메라가 있으면 3D 보정 개체(예: 구체)를 사용할 수 있습니다.

../../../_images/hand-eye-common-calibration-objects.png

Zivid Calibration Objects

Zivid supports the following calibration objects:

  • ArUco markers

  • Zivid calibration board

  • 9x6 grey-white checkerboards

Zivid calibration board

The main Zivid calibration board can be purchased at the Zivid WebShop. This board is also used for camera maintenance with infield correction. The Zivid calibration board has a 7x8 checkerboard made of 30 mm checkers and an ArUco marker in the corner. To use the board in hand-eye calibration, both the checkerboard and marker need to be detectable in each capture.

기울어진 칼리브레이션 보드 사진.

ArUco markers

Zivid hand-eye calibration also works with one or several ArUco markers as calibration objects. In general, the more markers are used, the better. You can generate and print ArUco markers at https://chev.me/arucogen/. Make sure that the markers are printed on a flat surface. The OpenCV dictionaries that we support are 4x4, 5x5, 6x6, and 7x7. One benefit of using ArUco markers for hand-eye calibration is that they are small. Another is that not all markers need to be detectable in each capture.

ArUco marker example
How large does the ArUco marker need to be?

We recommend having at least 7 pixels per ArUco bit side at the furthest imaging distance. The image below shows a zoomed-in image of an ArUco marker where each ArUco bit is represented by 8 pixels. How you can figure out the minimum needed size in mm is explained in the following example.

../../../_images/aruco_bit_8_pixels.png

For a 4x4 ArUco dictionary, there are 6 bits (4 inner bits and 2 outer bits), so you should aim for a minimum of 42 pixels per marker side.

Let us assume that you are using the Zivid 2+ M130 camera at a maximum imaging distance of 2 meters. The spatial resolution for this camera and distance is 0.5 mm (see Calculate FOV and Imaging Distance). Multiplying 0.5 mm by 42 pixels gives us 21 mm.

Therefore, to use the Zivid 2+ M130 at a distance of up to 2 meters, your ArUco marker should be at least 21 mm in size.

참고

You should leave some white space around your ArUco marker, with at least 1 bit of border. For the example above, this means 3.5 mm on each side (7 pixels multiplied by 0.5 mm).

9x6 grey-white checkerboards

Zivid 칼리브레이션 보드를 사용할 수 없는 경우, Zivid 핸드-아이 칼리브레이션은 9x6 회색-흰색 Zivid 체커보드에서도 작동합니다. 이 보드는 아래 제공된 PDF로 인쇄할 수 있습니다.

단순한 흰색과 회색 교정 보드의 그림.

회색 및 흰색 체커보드는 *.pdf 형식으로 다양한 사각형 크기로 다운로드할 수 있습니다.:

종이 기반 커버 층이 있는 KAPA 또는 유사한 보드 재료에 Zivid 체커보드를 인쇄하는 것을 권장합니다.

How To Get Good Quality Data On Zivid Calibration Object 에 대해 확인해보십시오.