ar_markers

Detection of hamming markers for OpenCV written in python.

Originally written by Max Brauer: github. All I did was clean up some little stuff and package it for use on pypi.

This package is able to read and create hamming markers, described in this blogpost.

Purpose

This project was for a robotics/computer vision class I taught Spring 2018. I wanted something simple enough we could go through the code and they could understood how it worked. I also taught them OpenCV, so I wanted something written in that. Eventually we made "street signs" and the students drove Roomba robots around on these "strees" (ok, really it was 3 inch wide black tape for the roads). When they detected an intersection, they used a camera to read the street sign (ar marker) and it told them to: go straight, turn left, or turn right.

Sometimes it isn't as robust as I would like, so you may have to move the target around before it gets recognized.

Install

The simplest way to install is:

pip install ar_markers

You will also need OpenCV 3.x as a minimum. On macOS you can do:

brew install opencv

Usage

There are two helper scripts:

• ar_markers_generate.py to generate the markers. Do ar_markers_generate.py --help to see the options
• ar_markers_scan.py to scan the marker. Once you have created and printed out a marker, hold the marker in front of your camera. You will see a blue border around the marker, (if detected) and a green number, showing the ID the marker represents.

or use in a program like:

#!/usr/bin/env python

from __future__ import print_function
import cv2
from ar_markers import detect_markers


if __name__ == '__main__':
        print('Press "q" to quit')
        capture = cv2.VideoCapture(0)

        if capture.isOpened():  # try to get the first frame
                frame_captured, frame = capture.read()
        else:
                frame_captured = False

        while frame_captured:
                markers = detect_markers(frame)
                for marker in markers:
                        marker.highlite_marker(frame)
                cv2.imshow('Test Frame', frame)
                if cv2.waitKey(1) & 0xFF == ord('q'):
                        break
                frame_captured, frame = capture.read()

        # When everything done, release the capture
        capture.release()
        cv2.destroyAllWindows()

BSD License

Copyright (c) 2007, Max Brauer All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.