libzoneminder-plugin-openalpr

Overview

libzoneminder-plugin-openalpr is a free, open source Licence Plate Recognition (LPR) plugin for the ZoneMinder CCTV sofware (https://github.com/ZoneMinder/ZoneMinder). It is based on openalpr library (https://github.com/openalpr/openalpr). The recognized license plates are added to Zoneminder's event notes.

Requirements

libzoneminder-plugin-openalpr requires:

• A ZoneMinder installation with the plugin framework
• The OpenALPR library

Installation

Debian Jessie (64 bits)

Currently the plugin framework is not supported in upstream ZoneMinder. ZoneMinder with plugin support can be built from the repository https://github.com/manupap1/ZoneMinder

Installation of the building environment

sudo apt-get install build-essential git devscripts

Compilation of ZoneMinder

git clone https://github.com/manupap1/ZoneMinder.git
cd ZoneMinder/
git fetch origin plugin_support:plugin_support
git checkout plugin_support
cp -R distros/debian8 ./debian
sudo apt-get install debhelper po-debconf dh-systemd autoconf automake quilt libphp-serialization-perl libgnutls28-dev libmysqlclient-dev libdbd-mysql-perl libdate-manip-perl libwww-perl libjpeg62-turbo-dev libpcre3-dev libavcodec-dev libavformat-dev libswscale-dev libavutil-dev libv4l-dev libbz2-dev libtool libsys-mmap-perl libnetpbm10-dev libavdevice-dev libdevice-serialport-perl libarchive-zip-perl libmime-lite-perl dh-autoreconf libvlccore-dev libvlc-dev libcurl4-openssl-dev libgcrypt20-dev libpolkit-gobject-1-dev libdbi-perl libnet-sftp-foreign-perl libexpect-perl libmime-tools-perl pkg-config
debuild

Installation of ZoneMinder plugin development library

cd ..
sudo dpkg -i libzoneminder-dev_*_amd64.deb

Compilation of OpenALPR

git clone https://github.com/openalpr/openalpr.git
cd openalpr
cp -R distros/debian ./
fakeroot debian/rules get-orig-source
sudo apt-get install debhelper git cmake quilt libopencv-dev libtesseract-dev libtesseract-dev libleptonica-dev liblog4cplus-dev libcurl3-dev uuid-dev
debuild

Installation of OpenALPR development library

cd ..
sudo dpkg -i libopenalpr-dev_*_amd64.deb libopenalpr2_*_amd64.deb libopenalpr-data_*_all.deb

Compilation of libzoneminder-plugin-openalpr

git clone https://github.com/manupap1/libzoneminder-plugin-openalpr.git
cd libzoneminder-plugin-openalpr
cp -R distros/debian ./
sudo apt-get install debhelper quilt dh-autoreconf pkg-config libboost-program-options1.55-dev libopencv-dev libopencv-core-dev libopencv-imgproc-dev
debuild

Installation of ZoneMinder, OpenALPR and libzoneminder-plugin-openalpr

cd ..
sudo apt-get install libavcodec56 libavdevice55 libavformat56 libavutil54 libbz2-1.0 libc6 libcurl3 libgcc1 libgcrypt20 libgnutls-deb0-28 libgnutls-openssl27 libjpeg62-turbo libmysqlclient18 libpcre3 libstdc++6 libswscale3 libvlc5 zlib1g debconf init-system-helpers perl libdevice-serialport-perl libimage-info-perl libjson-any-perl libsys-mmap-perl liburi-encode-perl libwww-perl libarchive-tar-perl libarchive-zip-perl libdate-manip-perl libdbi-perl libmodule-load-conditional-perl libmime-lite-perl libmime-tools-perl libnet-sftp-foreign-perl libphp-serialization-perl libav-tools rsyslog netpbm zip policykit-1 apache2 libapache2-mod-php5 php5 php5-mysql mysql-server
sudo dpkg -i libzoneminder-perl_*_all.deb zoneminder-database_*_all.deb zoneminder-core_*_amd64.deb zoneminder-ui-base_*_amd64.deb zoneminder-ui-classic_*_all.deb libopenalpr2_*_amd64.deb libopenalpr-data_*_all.deb libzoneminder-plugin-openalpr_*_amd64.deb

Configuration

After installation, please make some adjustments in file /etc/zm/plugins.d/openalpr.conf. Most of default values can be kept, but if you live in Europe, you can set the country_code setting to eu to improve reading of plates with EU format

All the next configuration steps are done through the web interface.

Firstly, the plugin loading has to be enabled in ZM options (please check the LOAD_PLUGIN setting in Config tab).

Then, you can configure the plugin settings from each Zone configuration page.

Available plugins are listed with a color code under the Plugins row:

• Default color - Plugin is not enabled for the zone
• Green - Plugin is enabled for the zone
• Grey - Plugin loading is disabled (please check LOAD_PLUGIN setting in Config tab)
• Orange - Plugin is enabled for the zone but not active (configuration setting mismatch)
• Red - ZoneMinder failed to load the plugin object (software error)

Once a plugin object is loaded, the Plugin configuration page is accessed by clicking on the plugin name.

The first options are available for all plugins:

• Enabled - A yes/no select box to enable or disable the plugin
• Require Native Detection - A yes/no select box to specify if native detection is required before to process plugin analysis. This option allow to limit CPU usage by using the plugin for post processing after native detection. This option is recommended for this plugin as it may use a lot of CPU ressources
• Include Native Detection - A yes/no select box to specify if native detection shall be included in alarm score and image overlay
• Reinit. Native Detection - A yes/no select box to specify if native detection shall be reinitialized after detection. ZoneMinder's native detection is performed by comparing the current image to a reference image. By design, the reference image is assigned when analysis is activated, and this image is not periodically refreshed. This operating method is not necessarily optimal because some plugins may require native detection only when motion is truly detected (current image different from the previous image). This option is recommended for libzoneminder-plugin-openalpr. For example, without this option enabled, if a vehicle appears and parks in the camera field of view, the native detection will be be triggered as long as the vehicle is parked, and therefore the plugin analysis would be performed for an unnecessary period of time. With this option enabled, the plugin analysis stops when the vehicle stops.
• Alarm Score - A text box to enter the score provided by the plugin in case of detection

The next options are specifics to this plugin and can be used to adjust the detection accuracy:

• Minimum Confidence - A text box to enter the minimum confidence level. All plates with a lower confidence level will be excluded.
• Min. Number of Characters - A text box to enter the minimum number of characters in a license plate. All plates with a lower number of detected characters will be excluded.
• Max. Number of Characters - A text box to enter the maximum number of characters in a license plate. All plates with a greater number of detected characters will be excluded.
• List of Targeted Plates - A list to specify targeted plates (detected plates will have a 100% confidence).
• Detect only Targeted Plates - A yes/no select box to specify if plates not in target list shall be ignored.
• Strict Targeting - A yes/no select box to specify if target matching shall be strict (plates must match exactly).
• Assume target matching - When strict targeting is off plates included in wider strings are detected (within the max. number of characters limit). This yes/no select box allow to specify if such detected plates shall be considered as being equal to the target. If yes is selected, the plugin will report these plates with the target string and with a 100% confidence. If no is selected, the plugin will report these plates individually. This option can be helpfull if the plate format includes a field for a logo which may be considered as a character by openalpr.

The configuration is saved to the database and applied when clicking on the Save button.

Using

When a license plate is detected, this triggers an event with alarmed frame(s). Depending on your configuration settings and video content, an event may contain multiple alarmed frames.

Licenses plates are stored in the event note field accessible by a click on the event detection cause.

Alarmed frames are highlighted with the plate's detection area(s).

The detected plate number(s) can be added in email or sms notifications by using the %ED% token in EMAIL_BODY or MESSAGE_BODY option.

Improvement / Contribution

Feel free to contribute, if you can:

• Report or fix an issue (https://github.com/manupap1/libzoneminder-plugin-openalpr/issues),
• Add a feature,
• Or just correct any grammar mistakes I have committed...

I am personally not in a position to provide videos content to test the plugin in all conditions. After some search to find footage with good quality and with optical settings adapted for LPR, I found this video on youtube: https://www.youtube.com/watch?v=ECIxQblzNWI. The video has been published by iFacility Group (http://www.ifacility.co.uk) and is currently included in the misc folder.

Any new video content is welcomed, if it meets the following criterias:

• Filmed with proper CCTV equipment (not smartphones or other IT devices),
• Resolution between PAL/NTSC or 2MP (above resolutions are not necessary and would require too much CPU ressources),
• Not a to wide field of view angle as this introduces video distorsions,
• If the vehicle is moving at speed above 30km/h, the video should be filmed with an angle not too far from the vehicle moving axis and with an optical lens allowing setting of focal length above 15mm (this should allow to track the license plate from a far enough distance),
• If the content is filmed in night conditions, the video should be filmed with a Day/Night camera and with infrared lighting (do not expect conclusive results in other conditions).