# Interactive calibration app

**URL:** <https://forum.opencv.org/t/interactive-calibration-app/9662>\
**Category:** C++\
**Tags:** calib3d, calibratecamera\
**Created:** [July 28, 2022, 11:09am UTC](https://forum.opencv.org/t/interactive-calibration-app/9662 "2022-07-28T11:09:39Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![LB94](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/lb94/32/1021_2.png) [@LB94](https://forum.opencv.org/u/LB94)\
**Post date:** [July 28, 2022, 11:09am UTC](https://forum.opencv.org/t/interactive-calibration-app/9662/1 "2022-07-28T11:09:39Z")

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Hi,  
I’m using the opencv interactive calibration app but I’m having some issues with circles pattern target. The app can detect the circles grid of my checkerboard but all the frames are rejected.

The checkerboard is perfectly flat however even if the circles grid is always detected, all the frames are rejected.

Do you know what can be the problem with a symmetric circles grid pattern?  
Why all my frames are rejected?

Thank you

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**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:** [July 28, 2022, 12:55pm UTC](https://forum.opencv.org/t/interactive-calibration-app/9662/2 "2022-07-28T12:55:05Z")

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pictures and settings please.

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<div class="post-metadata">

**Author:** ![LB94](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/lb94/32/1021_2.png) [@LB94](https://forum.opencv.org/u/LB94)\
**Post date:** [July 28, 2022, 3:19pm UTC](https://forum.opencv.org/t/interactive-calibration-app/9662/3 "2022-07-28T15:19:41Z")

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Thank you for your reply.

I solved the issue by modifying the source code. In the source code the circles grid geometry is defined as asymmetric. While my target is a symmetric circles grid. So the angles computed in CalibProcessor::checkLastFame() were always too large making the function return isFrameBad=True (frame rejected).  
So my solution was to replace the circle grid objectpoints definition from asymmetric to symmetric (like a chessboard).  
Now I can calibrate using a symmetric circles grid pattern

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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:** [July 28, 2022, 3:22pm UTC](https://forum.opencv.org/t/interactive-calibration-app/9662/4 "2022-07-28T15:22:00Z")

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for monocular vision it’ll be okay.

for stereo/multi vision you will get in trouble because the grid’s points might be ordered differently in each view, purely because of how the grid looks in that view. wrongly ordered points will destroy the calibration.

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<div class="post-metadata">

**Author:** ![LB94](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/lb94/32/1021_2.png) [@LB94](https://forum.opencv.org/u/LB94)\
**Post date:** [July 28, 2022, 3:27pm UTC](https://forum.opencv.org/t/interactive-calibration-app/9662/5 "2022-07-28T15:27:28Z")

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I’m not getting what you mean.  
Can you please explain with more details what you mean?

I’m using that pattern for the calibration, not for other tasks

Thank you

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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:** [July 28, 2022, 3:41pm UTC](https://forum.opencv.org/t/interactive-calibration-app/9662/6 "2022-07-28T15:41:41Z")

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is this for intrinsic calibration or extrinsic calibration?

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<div class="post-metadata">

**Author:** ![LB94](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/lb94/32/1021_2.png) [@LB94](https://forum.opencv.org/u/LB94)\
**Post date:** [July 28, 2022, 5:08pm UTC](https://forum.opencv.org/t/interactive-calibration-app/9662/7 "2022-07-28T17:08:27Z")

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Intrinsics only.

For the calculation of the extrinsic parameters of a stereo camera, you are right. I see your point

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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:** [July 10, 2023, 7:06pm UTC](https://forum.opencv.org/t/interactive-calibration-app/9662/8 "2023-07-10T19:06:14Z")

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A post was split to a new topic: [Interactive calibration app (chessboard pattern)](https://forum.opencv.org/t/interactive-calibration-app-chessboard-pattern/13813)