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This page provides guidelines and recommendations to consider when cabling and wiring USB-based and/or Ethernet-based OptiTrack motion capture system.
An Ethernet camera system networks via Ethernet cables. Ethernet-based camera models include Prime series (Prime 13, 13W, 17W, 41) and Slim 13E models. Ethernet cables not only offer faster data transfer rates, but they also provide power over Ethernet to each camera while transferring the data to the host PC. This reduces amount of required cables and simplifies the overall setup. Furthermore, Ethernet cables have much longer length capability (up to 100m), allowing the systems to cover large volumes.
Ethernet cameras connect to the host computer through a Gigabit (1000 Mb/second) Ethernet port. Note: the camera network should be segmented from the office or other local area networks to avoid interference and congestion. If the computer used for capture is connected to an existing network, then a second Ethernet port or add-on network card can be used to connect the camera network. When the camera network is not isolated, frame drops may occur.
Note: Turn off your computer's firewall for the particular network in order to connect the camera network to the host PC.
There are multiple categories for Ethernet cables, and each has different specifications for maximum data transmission rate and cable length. For an Ethernet based system, category 6 or above Gigabit Ethernet cables should be used. 10 Gigabit Ethernet cables – Cat6e, Cat6a, and Cat7 — are recommended in conjunction with a 10 Gigabit uplink switch for the connection between the uplink switch and the host PC in order to accommodate for the high data traffic.
Main components included in the Ethernet based system:
OptiTrack’s Ethernet cameras require PoE or PoE+ Gigabit Ethernet switches, depending on the camera's power requirement. The switch serves two functions: transfer camera data to a host PC, and supply power to each camera over the Ethernet cable (PoE). The switch must provide consistent power to every port simultaneously in order to power each camera. Standard PoE switches must provide a full 15.4 watts to every port simultaneously. Prime 17W and Prime 41 cameras have stronger IR strobes which require higher power for the maximum performance. In this case, these cameras need to be routed through PoE+ switches that provide a full 30 watts of power to each port simultaneously. Note that PoE Midspan devices or power injectors are not suitable for Ethernet camera systems.
The eSync is used to enable synchronization and timecode in Ethernet-based mocap systems. Only one device is needed per system, and it enables you to link the system to almost any signal source. It has multiple synchronization ports which allow integrating external signals from other devices. When an eSync is used, it is considered as the master in the synchronization chain.
If the number of cameras included in the system exceeds the number of ports available from the switch, a star topology setup with an uplink switch connecting subsequent switches will be required. In this case, large amounts of data will be transferred through the uplink switch. In order to cope high bandwidth, it is recommended use the 10 Gigabit uplink switch and connect to the host PC with a 10 Gigabit cable – Cat6a, Cat6e, and Cat7. Otherwise, system latency can increase and frame drops may occur.
A USB camera system provides high quality motion capture for small to medium size volumes at a relatively (compared to Ethernet cameras) affordable price range. USB camera models include the Flex series (Flex 3 and Flex 13) and Slim 3U models. USB cameras are powered by the OptiHub, which is designed to maximize the capacity of Flex series cameras by providing sufficient power to each camera, allowing tracking at long ranges. For each USB system, up to four OptiHubs can be used. When incorporating multiple OptiHubs in the system, use RCA synchronization cables to interconnect each hub. A USB system is not suitable for a large volume setup because the USB 2.0 cables used to wire the cameras have a 5 meter length limitation. If needed, up to two active USB extensions can be used when connecting the OptiHub to the host PC. However, the extensions should not be used between the OptiHub and the cameras.
The OptiHub is a custom-engineered USB hub that is designed to be incorporated in a USB camera system. It provides both power and external synchronization options. Standard USB ports do not provide enough power for the IR illumination within Flex 13 cameras and they need to be routed through an OptiHub in order to activate the LED array.
OptiSync is a custom synchronization protocol which allows sending the synchronization signals through the USB cable. It allows each camera to have one USB cable for both data transfer and synchronization
instead of having separate USB and daisy-chained RCA synchronization cables as in the older models.
Difference Between OptiSync and Wired Sync
The OptiSync is a custom camera-to-camera synchronization protocol designed for Flex series cameras. The OptiSync protocol sends and receives sync signals over the USB cable, without the need for RCA sync cables. This sync method is only available when using Flex 3 or Flex 13 cameras connected to the OptiHub.
The Wired Sync is a camera-to-camera synchronization protocol using RCA cables in a daisy chain arrangement. With a master RCA sync cable connecting the master camera to the OptiHub, each camera in the system is connected in series via RCA sync cables and splitters. The V100:R1 (Legacy) and the Slim 3U cameras utilize Wired Sync only, and therefore any OptiTrack system containing these cameras need to be synchronized through the Wired Sync. Wired Sync is optionally available for Flex 3 cameras.
When connecting hubs to the computer, load balancing becomes important. Most computers have several USB ports on the front and back, all of which go through two USB controllers. It is recommended (especially in larger camera count systems) that you evenly split the cameras between the USB controllers to make the best use of the available bandwidth.
Tracking Bars — V120:Duo and V120:Trio — are also USB camera models, but they are standalone devices featuring an integrated hub and cameras. Therefore, their USB output is directly connected to the host PC without routing through the OptiHub.
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