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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
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Getting complex numbers when calculating intrinsic camera parameters

I'm trying to implement Zhang's algorithm for camera calibration in MATlab. The steps to do that should be pretty straight forward and easy to implement, especially using MATLab. However, I've been stuck at a point where I'm getting complex numbers…
hussein zaiter
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Rolling window for co-variance matrix

I got a 4-years time series of asset returns and I'm trying to perform a rolling-window in order to estimate the variance-covariance matrix with a calibration period of 6 months. in general, consider as dataset a matrix which includes the returns of…
Rfun2018
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Measure real distance between two known lines with OpenCV

I have a problem with measuring the real world length of a line between two known lines with only one single image. Please have a look at this sketch: The following steps were realized: Calibrated the camera Detect the line end points in the…
Basman
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Scikit correct way to calibrate classifiers with CalibratedClassifierCV

Scikit has CalibratedClassifierCV, which allows us to calibrate our models on a particular X, y pair. It also states clearly that data for fitting the classifier and for calibrating it must be disjoint. If they must be disjoint, is it legitimate to…
sapo_cosmico
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How does Genuino Arduino 101 Intel Curie Autocalibration (Ax Ay Az) process works?

I am reading the source code file CurieIMU.cpp#L409, made by Intel for Arduino/Genuino 101. I have some questions: How does auto-calibration work in this specific case? This is not very clear to me. Why the offset can be assumed to be linear? Is…
Andrea Ciufo
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Radius Networks Beacon calibration with locate App

we are trying to develop a location app based on beacons. At the moment we are trying to analyze different options and we are surprised the tests carried out with the beacon of the brand radius networks. We have 3 radius networks dot beacons and we…
Kepa Santos
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How to calibrate an android device's microphone

I am working on a research project that involves recording community noise nuisances using an android device to perform some complex digital signal processing analysis and calculate some metrics. My supervisor instructed me to calibrate the…
Aditya
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Why resizing an image in OpenCv decreases the reprojection error of a camera calibration?

I'm using OpenCv to calibrate a camera. Firstly, I was using the original resolution, but then I realize that if I resize the image (downsample) I could get a lower reprojection error. Why this happens?
AnnaB
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Extrinsic camera calibration OpenCV

I am attempting to calibrate the extrinsics of four cameras that I have mounted on a set-up. They are pointing 90 degrees apart. I have already calibrated the intrinsic paramteres, and I am thinking of using an image of a calibration pattern to find…
NoShadowKick
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WatchOS 2 calibrate Pedometer

I want to build a running application where you can also run only with your Apple Watch (and leave your phone at home). this site (http://www.cnet.com/how-to/how-to-calibrate-the-apple-watch-for-improved-accuracy/) states that Calibration is…
iVentis
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Accelerometer and calibration - iPhone SDK

I need to use the functionality of an accelerometer in my iPhone game. I just have to move an image by tilting the device. However most videos on YouTube just show the tilt feature that is somehow inverted and forget to include the calibration. I…
lab12
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Calculate model calibration during cross-validation in caret?

first time poster here, so apologies for rookie errors I am using the caret package in R for classification. I am fitting some models (GBM, linear SVM, NB, LDA) using repeated 10-fold cross validation over a training set. Using a custom…
Achekroud
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How to "correctly" reconstruct intrinsic matrix from homography

I tried very hard to read the following paper. Z. Zhang. Flexible Camera Calibration By Viewing a Plane From Unknown Orientations. International Conference on Computer Vision (ICCV'99), Corfu, Greece, pages 666-673, September 1999. This paper…
Alex Lin
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Converting CSV to XML

I'm currently trying to make the input file for a hydrologic model (HBV-light) compatible with external calibration software (PEST). HBV-light requires that it's input files be in XML format, while PEST can only read text files. My issue relates to…
Geogrammer
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Is the iPhone accelerometer calibrated? Gravity measurement changes depending on orientation

I'm doing some test with iPhone 4S accelerometer. If I take the raw data in Z-axis (telephone rest over desktop) I get an acceleration 9.65-9.70 m/s2 (after g conversion by 9.8261). But if i have the telephone resting over edge, the measurement of…
albertofr86
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