GigE Vision – What it is

GigE Vision is a standard managed by the Automated Imaging Association that provides the vision industry with an open framework for transferring images and control signals between cameras and PCs over standard Gigabit Ethernet (GigE) connections. From day one, the GigE Vision framework was designed to support a range of different performance levels and feature sets. This approach was taken on purpose so that vendors would have room to innovate and differentiate their products, and vision system designers and integrators would have the broadest possible selection of compliant products with which to work.

GigE Vision Version 1.0, ratified in May 2006, has four main elements:

• Device Discovery, which defines how compliant devices such as cameras obtain IP addresses and are identified on the network;
• GVCP (GigE Vision Control Protocol), which defines how to specify stream channels and control and configure compliant devices;
• GVSP (GigE Vision Stream Protocol), which defines how images are packetized and provides mechanisms for cameras to send image data and other information to host computers; and
• An XML (extensible mark-up language) description file that provides the equivalent of a computer-readable datasheet of features in compliant devices. This file must be based on the schema defined by the EMVA's (European Machine Vision Association) GenICam™ standard and include the seven features in Table 1

In addition to these elements, GigE Vision includes standard feature naming conventions for recommended and optional features in GigE cameras beyond the mandatory seven.

GigE Vision – What it is NOT

Compliance with the GigE Vision standard means only that products follow a certain connectivity method. It is not a performance guarantee. Compliance does not, for example, mean that a product will operate reliably, recover from packet loss in the GigE connection, deliver deterministic real-time operation, or meet the precisely timed synchronization requirements of multi-element applications.

As with any other vision product, GigE Vision cameras and PC software must be assessed for reliability and quality of implementation.

GenICam

The introduction of GenICam offers great hope for developers who want to easily use and interchange a range of GenICam-compliant cameras, regardless of the interface and/or protocol technologies, using a compliant application running on their PCs.

• Cameras
  
• Transport Layers
  
• Libraries

Simply put, these product categories form a chain, in which image data is transported from the camera via Transport Layers (low-level software drivers or frame grabbers) to Libraries (or applications) running on a PC. In the other direction, control data can be sent from the PC to the camera, allowing users to adjust features and settings inside the camera. A key objective of GenICam is to allow users to control a wide range of cameras – GigE Vision, Camera Link, IEEE 1394 IIDC, USB UVC, and others – using the same application.

• GenApi – an XML description file format defining how to capture the features of a device and how to access and control these features in a standard way
  
• The GenICam Standard Features Naming Convention – common naming convention for camera features, which promotes interoperability between products from different manufacturers
  
• GenTL – a generic Transport Layer Interface, between software drivers and libraries, that transports the image data from the camera to the application running on a PC

The use of GenICam is not mandatory for compliance with GigE Vision. Other, proprietary, camera control methods are also allowed.