Video
Video timing is the most cost-effective method for high accuracy. Being visual, it is capable of greater accuracy than manual timing, while being less expensive than Photo Finish equipment. However this requires much more than a standard video camcorder.
The system outlined here is experimental. It is not in use today.
The System
This is an image-based timing system (experimental) consisting of:
- 1080p 25 High Definition video
- an accurate time source
- a computer to process the video
- a network to transmit times from Start and Finish to a results computer
- software to calculate results.
Video
A video camera capable of recording 1080p 25 High Definition video direct to disk, with:
- intraframe compression
- high sensitivity sensor
- high fixed shutter speed, fixed aperture, variable ISO
- moderate telephoto lens
The camera needs to be mounted in a fixed position.
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The camera records 25 full frames per second, and therefore the timing resolution is to 0.04 of a second. The timing accuracy is determined by the time source providing timecode to the video camera.
Download the video to see this in action.
Time source
It is just a mistake to assume, because the camera displays time, that it is accurate. Professional video uses an external time source to provide clock accuracy.
Each timing station needs a separate but synchronised time source. The time souce provides an accurate timecode input to the video, to replace the internal clock. The time source accuracy needs to exceed the 25 frames per second resolution of the video - that is, to use the 0.04 second resolution provided by the frame rate, you need to have a time souce that is more accurate than that for the entire duration of the race. This means the time source needs to have a TXCO or GPS clock.
Process
The line should be clearly marked in the video, either by an external vertical object (wire or post) at both ends of the line, or by a superimposed image of a line. The width of the line in the frame should obscure less than 20 centimeters of a boat at the furthest end of the line.
A computer with standard editing software is required to view the images. The computer does not supply the times. As with photo finish, an Evaluator views the images to determine the frame in which a bow crosses the line. The time can be read from the frame or from the time track.
A backup stopwatch is operated by a separate timing team.
Although the video will identify most crews, a separate Spotter and Sequencer should be used in case the video is not clear. This may occur with glare, shadow, or missing boat number.
Network
An IP-based network is used to send times to a results computer. The network can be mobile or wireless, depending on circumstances.
Software
A spreadsheet or results software is used to compile the results.