NAME

       mrgingham-observe-pixel-uncertainty - Evaluate observed point distribution from stationary observations

SYNOPSIS

         $ observe-pixel-uncertainty '*.png'
           Evaluated 49 observations
           mean 1-sigma for independent x,y: 0.26

         $ mrcal-calibrate-cameras --observed-pixel-uncertainty 0.26 .....
         [ mrcal computes a camera calibration ]

DESCRIPTION

       mrgingham has finite precision, so repeated observations of the same board will produce slightly
       different corner coordinates. This tool takes in a set of images (assumed observing a chessboard, with
       both the camera and board stationary). It then outputs the 1-standard-deviation statistic for the
       distribution of detected corners. This can then be passed in to mrcal: 'mrcal-calibrate-cameras
       --observed-pixel-uncertainty ...'

       The distribution of the detected corners is assumed to be gaussian, and INDEPENDENT in the horizontal and
       vertical directions. If the x and y distributions are each s, then the LENGTH of the deviation of each
       pixel is a Rayleigh distribution with expected value s*sqrt(pi/2) ~ s*1.25

       THIS TOOL PERFORMS VERY LIGHT OUTLIER REJECTION; IT IS ASSUMED THAT THE SCENE IS STATIONARY

OPTIONS

   POSITIONAL ARGUMENTS
         input                 Either 1: A glob that matches images observing a
                               stationary calibration target. This must be a GLOB. So
                               in the shell pass in '*.png' and NOT *.png. These are
                               processed by 'mrgingham' and the arguments passed in
                               with --mrgingham. Or 2: a vnlog representing corner
                               detections from these images. This is assumed to be a
                               file with a filename ending in .vnl, formatted like
                               'mrgingham' output: 3 columns: filename,x,y

   OPTIONAL ARGUMENTS
         -h, --help            show this help message and exit
         --show {geometry,histograms}
                               Visualize something. Arguments can be: "geometry":
                               show the 1-stdev ellipses of the distribution for each
                               chessboard corner separately. "histograms": show the
                               distribution of all the x- and y-deviations off the
                               mean
         --mrgingham MRGINGHAM
                               If we're processing images, these are the arguments
                               given to mrgingham. If we are reading a pre-computed
                               file, this does nothing
         --num-corners NUM_CORNERS
                               How many corners to expect in each image. If this is
                               wrong I will throw an error. Defaults to 100
         --imagersize IMAGERSIZE IMAGERSIZE
                               Optional imager dimensions: width and height. This is
                               optional. If given, we use it to size the "--show
                               geometry" plot

REPOSITORY

       <https://github.com/dkogan/mrgingham>

AUTHOR

       Dima Kogan, "<dima@secretsauce.net>"

LICENSE AND COPYRIGHT

       This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser
       General Public License as published by the Free Software Foundation; either version 2.1 of the License,
       or (at your option) any later version.

       Copyright 2017-2018 California Institute of Technology

       Copyright 2017-2018 Dima Kogan ("dima@secretsauce.net")

mrgingham 1.26                                     2025-03-19                                       MRGINGHAM(1)