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GigE
Vision
Emerging Standard for Machine Vision Cameras |
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GigE
Camera Index
GigE Vision - Gigabit Ethernet
Cameras for Industrial Applications
Camera interface standards for
machine vision cameras have evolved over the last ten years. A
decade ago, industrial digital cameras were very difficult to
install and integrate into machine vision systems. The difficulty
was largely because there were no camera interface standards.
System integrators and end users desparately needed something more
standardized.
In the late 90's, the AIA formed
a camera interface standard based on channel link, a parallel bus
designed particularly for laptop computer displays. By defining a
standard cable and connector, together with some standardized
signal assignments, the Cameralink™ standard was born. Around
the same time, IEEE-1394 firewire cameras were conforming to a
digital camera interface standard called DCAM, now more commonly
known as IIDC. The DCAM (IIDC) camera interface standard went
further than Cameralink in that it not only defined a standardized
hardware interface but also defined a standardized software
control interface making DCAM-compliant firewire cameras truely
plug and play. Until recently, these two interfaces have dominated
the industrial digital camera market.
However, there is a new interface
standard that supasses the advantages of previous standards. The
newly released AIA GigE Vision™ standard for Gigabit Ethernet
cameras is now the state of the art interface for high-performance
digital cameras for machine vision and industrial applications.
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What is Gig-E?
GigE, or Gigabit Ethernet, is the
newest generation of Ethernet . Every one is familiar with
Ethernet since it is the ubiquitous means of connecting a computer
to a network. Standard Ethernet has a maximum data rate of 10
megabits per second (Mbps) and Fast Ethernet has a maximum data
rate of 100 Mbps, but Gigabit Ethernet is much faster at 1000
Mbps. Standard Ethernet and Fast Ethernet are too slow for
streaming uncompressed image data, and way too slow for machine
vision cameras. Gigabit Ethernet (GigE), however, with its maximum
data rate of 1000 Mbps, or 1 gigabit per second (Gbps) is capable
of handling streaming image data and of providing reliable
transmission of image data from high performance machine vision
cameras such as the Gigabit Ethernet cameras from Prosilica
Inc. Prosilica's GigE cameras are capable of steaming data at
a sustained rate of 125 megabytes per second over their gigabit
Ethernet interface.
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What is GigE Vision?
The GigE
Vision™ standard from the AIA
is an interface standard for high-performance machine vision
cameras that is widely supported in the industrial imaging
industry. GigE (Gigabit Ethernet), on the other hand, is simply
the network structure on which GigE Vision is built. The GigE
Vision standard includes both a hardware interface standard
(Gigabit Ethernet), communications protocols, and standardized
means of communicating with, and controlling, a camera. The GigE
Vision camera control registers are based on a command structure
called GenICam which is administered through the European Machine
Vision Association (EMVA).
GenICam seeks to establish a common camera control interface so
that third party software can communicate with cameras from
various manufacturers without customization. GenICam is
incorporated as part of the GigE Vision standard. GigE Vision is
analogous to Firewire's DCAM (IIDC) and has great value for
reducing system integration costs and for improving ease of use.
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GigE Vision is quite exciting
because it provides many features that are unavailable in any
other camera interface. The combined features of high data rates
(required for uncompressed video or imaging applications),
ubiquitous computer interface hardware, low cost cabling, and
widespread popularity make Gigabit Ethernet an attractive
interface option for machine vision cameras. With the advent of
GigE Vision, a standardized camera communication protocol from
the Advanced Imaging Association (AIA), GigE has become more
attractive still. Here are a few of the compelling benefits of
GigE Vision-compliant cameras:
- Gigabit Ethernet ports are
common on PCs and laptop computers, so there is no need
for special interface cards or expensive/complicated frame
grabbers in order to operate a GigE Vision camera.
- GigE provides high
bandwidth to transmit uncompressed image data from a
camera to a host computer in real time at speeds that
exceed the requirements of most industrial machine vision
applications. This substantially negates the need for
complex and expensive interfaces like Cameralink.
- Gigabit Ethernet provides
a high performance camera interface to convey control and
image data over long cable lengths. Cable lengths up to
100 meters using inexpensive CAT5e cabling are possible;
even longer distances are possible using switches or fiber
optics. Such long cable lengths far exceed the maximum
cable lengths of Cameralink, firewire, and USB.
- GigE Vision is compatible
with standard Gigabit Ethernet hardware allowing
networking of cameras. This is especially useful in
situations requiring multiple views and opens up new
machine vision applications in Intelligent Traffic Systems
(ITS) and public security imaging.
- GigE Vision allows
multicasting of image data simultaneously to multiple
computers for distributing the image processing load
across separate computers.
- CAT5e or CAT6 Ethernet
cables can be easily manufactured on-site using low cost
cabling and tools. This feature is especially useful for
outdoor installations where cameras may be mounted on
poles or buildings and where the cable must be routed as
the site demands.
- The new GigE Vision
standard provides ease of use that surpasses other common
camera interfaces.
- The fast successor to
GigE, 10GigE, offers 10 gigabit per second (Gbps) data
rates that when applied to cameras means that parallel
interfaces like Camera Link are no longer be necessary
even for high-speed applications
GigE Vision cameras, such as
Prosilica's GE-Series and GC-Series, are machine-vision cameras
that supply uncompressed
image data in real time, usually at very high data rates, that is
suitable for image analysis.
Most other types of Ethernet
camera are not suited to machine vision because they supply only
compressed image data, and that only at very limited data rates.
Some so-called 'smart cameras' use Ethernet to transmit non-image
data from the camera to a network, but these are generally
application specific image sensors that are not suited to
generalized imaging.
GigE Vision cameras such as
Prosilica's GigE Vision cameras are specially designed to handle
the dataflow in dedicated hardware providing uncompressed, very
fast, very reliable data throughput in a form that is suitable for
computer analysis.
Prosilica currently offers wide
selection of CCD and CMOS machine vision cameras that conform to
the GigE Vision standard providing an ease of use and integration
that has not previously been available. |
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