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I am doing a project on calibrating stereo ZED camera and finding its accuracy and compare with the Manufacturer's accuracy of 1% at 1m depth accuracy. For this purpose , the formula to calculate the depth accuracy is $dz = (z^2 * de) / (f * b)$ but how do we calculate $z$ , $de$ and $f$. Is is taken from matlab stereo-callibration app which gives 'Stereoparameter' ?

$dz$ is the depth error in meters, $z$ is the depth in meters, $de$ is the disparity error in pixels, $f$ is the focal length of the camera in pixels and $b$ is the camera baseline in meters.

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  • $\begingroup$ Can you name the parameters? $\endgroup$
    – Ben ♦
    Dec 16, 2016 at 2:53
  • $\begingroup$ dz is the depth error in meters, z is the depth in meters, de is the disparity error in pixels, f is the focal length of the camera in pixels and b is the camera baseline in meters. $\endgroup$
    – user137000
    Dec 16, 2016 at 3:48
  • $\begingroup$ You have to "estimate" your disparity error somehow (depending you the stereo matching algorithm used?) and you should be set. f and b are camera constants and z is the depth in which you make the measurement. $\endgroup$
    – Kozuch
    Dec 16, 2016 at 23:21
  • $\begingroup$ also see this answer: robotics.stackexchange.com/a/9714/1021 $\endgroup$
    – Kozuch
    Dec 16, 2016 at 23:22
  • $\begingroup$ @Kozuch Thanks for replying. I have just callibrated 11 set of stereo images in matlab stereo calibration app and have got intrinsic and extrinsic parameters . Is it possible to get the disparity error from this parameter ?. As I am using the images from ZED stereo camera the b is 120mm and FOV is known 110degree , so how do I get the focal length in this case ? $\endgroup$
    – user137000
    Dec 17, 2016 at 1:20

2 Answers 2

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You have to "estimate" your disparity error somehow (depending you the stereo matching algorithm used etc.) and you should be set. f and b are camera constants and z is the depth in which you make the measurement.

You can also see my answer on a related question: How can I improve ZED Camera precision?

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This paper shows an approximation of the RMS error of the ZED camera as a function of distance.Depth Data Error Modeling of the ZED 3D Vision Sensor from Stereolabs

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  • $\begingroup$ The link appears to be broken. Perhaps you could include the main points in your answer. $\endgroup$
    – sempaiscuba
    Aug 10, 2018 at 15:34
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    $\begingroup$ Welcome to Robotics Luis Ortiz. Thanks for your answer but we are looking for comprehensive answers that provide some explanation and context. Very short answers cannot do this, so please edit your answer to explain why it is right. Additionally, we prefer answers to be self contained where possible. Links tend to rot so answers which rely on a link can be rendered useless if the linked to content disappears. If you add more context from the link, it is more likely that people will find your answer useful. $\endgroup$
    – Chuck ♦
    Aug 10, 2018 at 15:58

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