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Questions tagged [calibration]

Use this tag for questions related to the process of adjusting the output or indication on a measurement instrument.

443 questions
118
votes
6 answers

Android accelerometer accuracy (Inertial navigation)

I was looking into implementing an Inertial Navigation System for an Android phone, which I realise is hard given the accelerometer accuracy, and constant fluctuation of readings. To start with, I set the phone on a flat surface and sampled 1000…
woodstock365
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15
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3 answers

How to Calibrate Android Accelerometer & Reduce Noise, Eliminate Gravity

So, I've been struggling with this problem for some time, and haven't had any luck tapping the wisdom of the internets and related SO posts on the subject. I am writing an Android app that uses the ubiquitous Accelerometer, but I seem to be getting…
malfunction
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13
votes
1 answer

Is Apple's iPhone magnetometer calibration working properly?

I'm currently developing an iPhone App (on iPhone 5, iOS 7, Xcode 5) which requires a very accurate determination of the current attitude. The "attitude" of CMDeviceMotion does not fulfil these requirements because Apple's sensor fusion algorithm…
user2980195
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11
votes
4 answers

Fisheye/Wide-Angle lens Calibration in OpenCV

I know the default OpenCV Calibration systems model a Pinhole camera, but I'm working with a system using extremely wide FOV lens (187-degrees). If there any existing way to do this in OpenCV, or to work with just wide lenses? Or will I have to…
Yeraze
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10
votes
2 answers

Color calibration with color checker using using Root-Polynomial Regression not giving correct results

For a quantification project, I am in need of colour corrected images which produce the same result over and over again irrespective of lighting conditions. Every image includes a X-Rite color-checker of which the colors are known in matrix…
Rivered
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10
votes
2 answers

Image center in the calibration matrix

I have a camera and a 3D object, I have calculated the camera matrix as given in this. The image captured using the camera is having size 1600x1200. But in the camera matrix I am not getting the value of image centers properly. Instead of 800, 600…
Deepak
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10
votes
6 answers

Wide angle lenses calibration with Opencv

I'm using a wide-angle lens (178º Diagonal FOV ) and I'm trying to calibrate it properly using Opencv Calibration module. All the detection and calibration process are working fine, but the result is very poor. I have tried many different…
Josep Bosch
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9
votes
2 answers

OpenCV for Unity : 4-point calibration/reprojection

It is my first post on Stack so I'm sorry in advance for my clumsiness. Please let me know if I can improve my question anyway. ► What I want to achieve (in a long term): I try to manipulate my Unity3d presentation with a laser pointer using OpenCV…
IronWolf
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9
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3 answers

How to calculate extrinsic parameters of one camera relative to the second camera?

I have calibrated 2 cameras with respect to some world coordinate system. I know rotation matrix and translation vector for each of them relative to the world frame. From these matrices how to calculate rotation matrix and translation vector of one…
Karmar
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9
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2 answers

To calculate world coordinates from screen coordinates with OpenCV

I have calculated the intrinsic and extrinsic parameters of the camera with OpenCV. Now, I want to calculate world coordinates (x,y,z) from screen coordinates (u,v). How I do this? N.B. as I use the kinect, I already know the z coordinate. Any help…
Paul
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8
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1 answer

OPENCV: Calibratecamera 2 reprojection error and custom computed one not agree

I have a python script that uses the calibratecamera2 method to calibrate a camera from a few views of a checker board. After a successful calibration I go after all original points and do some plots and compute again the re-projection error. My…
Josep Bosch
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7
votes
2 answers

Cv2 findChessboardCorners fails to find corners

I am using cv2 findChessBoardCorners for camera calibration in a vision application. My call to the function looks like this: def auto_detect_checkerboard(self, image): retval, corners = cv2.findChessboardCorners(image, (7, 7),…
Birdfriender
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7
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1 answer

How Kitti calibration matrix was calculated?

I working with other dataset (no kitti), but I need to convert it in kitti dataset format. I can't understand how calibration matrices were calculated in kitti. Example: camera 2 (P2) calibration matrix from calib.txt: [718.856 0 607.1928 …
ForceQuell
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7
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2 answers

The coordinate system of pinhole camera model

Recently, I have been studying the pinhole camera model, but I was confused with the model provided by OpenCV and the "Multiple View geometry in computer vision" textbook. I know that the following photo is a simplified model which switch the…
Alex Lin
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6
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1 answer

understanding sklearn calibratedClassifierCV

Hi all I am having trouble understanding how to use the output of sklearn.calibration.CalibratedClassifierCV. I have calibrated my binary classifier using this method, and results are greatly improved. However I am not sure how to interpret the…
ciskoh
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