Download Anthony Ogidi LO1/Whit Smith/David Keezer Turret Trackers Motion

Anthony Ogidi
LO1/Whit Smith/David Keezer
Turret Trackers
Motion Detection Software and Hardware
Introduction
Motion detection technology involves the use of sensors or optical flow to identify changes that
may occur within a frame of reference. Motion detection is widely used in a variety of fields including
cameras, defense artillery, and security systems. Motion detection in sensors work by bouncing signals
off moving objects and measuring the speed of the reflected wave while optical flow tracks changes that
may occur in pictures within a specific frame of reference.
Optical flow
Most digital cameras offer the option to perform motion detection. These cameras have an optical
lens that is used in a technique known as optical flow. Optical flow works by recording an apparent
change between surrounding images and an object in motion[1]. There is often a delay that occurs
between the time the button on a camera is pressed and the time a picture is taken. This delay is caused by
the camera registering and comparing several images to identify the background and focusing on changes
that may occur within the registered images. Advancement in technology by Canon has help create
cameras that detects motion faster in order to eliminate the lag that occurs before a picture is taken. The
price range for motion detection cameras vary based on the algorithm used in the optical flow process.
Cheaper models of cameras might give a false motion reading due to changes in sunlight or wind which
might result in poor image quality. More advanced cameras like the Canon EOS 5D Mark II offers a
complex lens that is capable of differentiating the minor changes in the background and auto focuses on
the object that in motion within nanoseconds [2]. Canon is currently working on research to implement
effective motion detection within the field of nanotechnology to offer in cell phones and other devices
that require smaller more compact cameras.
Software motion detection is a new and emerging technology that allows any camera be used for
motion detection. The software works by simply using the principles of optical flow. A background image
is prerecorded and is cross referenced to a new image which is then digitized to identify any movement
that was not present in the initial image [3]. This software’s provide an additional functionality to any
webcam at an affordable price. Some of these software’s also have multi webcam capabilities which can
be used to monitor multiple webcams simultaneously and can send an alert or perform a specific function
when motion is detected. Some free motion detection softwares include Dorgem 2.1, AbelCam 3.1.0, and
Senriska.
Sensors
Infrared Sensors are widely used in home security systems. Infrared sensors work by observing
changes in temperature within a specified area. Like in the optical flow technique the background
temperature is constantly monitored. When a significant change in temperature is observed a response
such as an alarm is triggered by the system. A problem with infrared technology is that it can result in a
false reading due to the fact that it monitors temperature. It might not be ideal in certain situations such as
kitchens or outdoors where sun interference might occur. Mace offers several in home low budget
infrared sensors used to activate alarms.
Microwave sensors and ultrasonic sensors work by bouncing signals off an object and measuring
the reflection [4]. The ultrasonic echo is received by a transducer before it is amplified by an amplifier
based on transistors [5]. This technology is most commonly used in speed detectors. It offers several
advantages including weather resistant, long range detection, adjustable sensitivity, and many more. The
KMY 10 microwave sensor works using the Doppler Effect to transmit low energy microwave radiation
which reflects off objects [6]. A problem with microwave and ultrasonic sensors is loss that may occur if
the reflected signal gets lost and never reaches the detector.
[1]
David D. Busch, Digital SLR Cameras & Photography for Dummies.2nd ed. NJ: Wiley
Publishing, 2007.
[2]
“EOS 5D,” [www.usa.cannon.com], [cited 2010 Jan 23], Available HTTP:
http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&fcategoryid=139&modelid=
11933
[3]
Infineon Technologies, “Microwave Motion Sensor,” Online Datasheet cited 2010 Jan 25
http://www.datasheetcatalog.org/datasheet/infineon/1-kmy10.pdf
[4]
Randal C. Nelson, “Qualitative Recognition of Motion Using Temporal Texture'', CVGIP Image
Understanding, Vol. 56, 1, July 1992, 78-89.
[5]
Dusan S. Zrnic, Richard J. Doviak, Doppler Radar And Weather Observations, Dover
Publications 2006.
[6]
Fleuret Francois, 10th European Conference on Computer Vision, Marseille, October 12, 2008.