# How to calibrate stereo

**URL:** <https://forum.opencv.org/t/how-to-calibrate-stereo/7454>\
**Category:** Uncategorized\
**Tags:** calib3d, stereo-calibration\
**Created:** [February 5, 2022, 8:26pm UTC](https://forum.opencv.org/t/how-to-calibrate-stereo/7454 "2022-02-05T20:26:14Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Sencis](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/sencis/32/4059_2.png) [@Sencis](https://forum.opencv.org/u/Sencis)\
**Post date:** [February 5, 2022, 8:26pm UTC](https://forum.opencv.org/t/how-to-calibrate-stereo/7454/1 "2022-02-05T20:26:14Z")

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After numerous attempts to calibrate the cameras, the result is always something like this:

 ![IMG_20220202_015800_198](https://us1.discourse-cdn.com/flex020/uploads/opencv/original/2X/9/9f56d540062879858f875ff667cf21597bb42e66.jpeg)

Is there any special way to calibrate cameras, what could be the problem?

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<div class="post-metadata">

**Author:** ![crackwitz](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/crackwitz/32/14_2.png) [@crackwitz](https://forum.opencv.org/u/crackwitz)\
**Post date:** [February 5, 2022, 9:25pm UTC](https://forum.opencv.org/t/how-to-calibrate-stereo/7454/2 "2022-02-05T21:25:21Z")

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your board is symmetric (180 degree rotational).

use a board with one dimension being odd and the other being even. that’ll not be rotationally symmetric.

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<div class="post-metadata">

**Author:** ![Sencis](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/sencis/32/4059_2.png) [@Sencis](https://forum.opencv.org/u/Sencis)\
**Post date:** [February 6, 2022, 7:05am UTC](https://forum.opencv.org/t/how-to-calibrate-stereo/7454/3 "2022-02-06T07:05:43Z")

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A board with asymmetrical circles would will be better, like on dji drones?

 ![14660127065741986](https://us1.discourse-cdn.com/flex020/uploads/opencv/original/2X/e/e3ef0dc049e42a4cc26fe668e84dd3f8513f592e.png)

 ![Circle gride](https://us1.discourse-cdn.com/flex020/uploads/opencv/original/2X/4/4132b165b4d3185e0223ed19ab3d508e0a9b6ec1.png)

This chessboard is made of four sheets of A4, maybe the problem is that they are not positioned correctly?

 ![20220206_103915](https://us1.discourse-cdn.com/flex020/uploads/opencv/original/2X/9/951aa6cd640aaccea55b1549c75e1ec65e6fd5f5.jpeg)

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<div class="post-metadata">

**Author:** ![crackwitz](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/crackwitz/32/14_2.png) [@crackwitz](https://forum.opencv.org/u/crackwitz)\
**Post date:** [February 6, 2022, 1:56pm UTC](https://forum.opencv.org/t/how-to-calibrate-stereo/7454/4 "2022-02-06T13:56:36Z")

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1. picture: **bad**. has 180 degree rotational symmetry.
2. picture: good. has no rotational symmetry.
3. picture: **bad**. has 180 degree rotational symmetry.

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<div class="post-metadata">

**Author:** ![Sencis](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/sencis/32/4059_2.png) [@Sencis](https://forum.opencv.org/u/Sencis)\
**Post date:** [February 17, 2022, 9:28am UTC](https://forum.opencv.org/t/how-to-calibrate-stereo/7454/6 "2022-02-17T09:28:29Z")

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Thanks now I’m using a printed size board on A2 asymtric gride, but it looks like it’s not just the board. Array objectsPoints, what units of measurement should I enter the size of the circle or the distance between the circles for variable squareSize? In integers, for example, 50 mm circle diameter of  
70mm spacing distance?

 ![photo5197699018971527793](https://us1.discourse-cdn.com/flex020/uploads/opencv/original/2X/d/d30711b190004902d6e9f04d18585d0523d28098.jpeg)

```auto
case Settings::ASYMMETRIC_CIRCLES_GRID:
  for( int i = 0; i < boardSize.height; i++ )
     for( int j = 0; j < boardSize.width; j++ )
        corners.push_back(Point3f(float((2*j + i % 2) * squareSize), float(i* squareSize ), 0));
  break;

```