Milestone LPR 1.0 - Manual (Page 34)

Milestone XProtect
®
LPR 1.0 Administrator's Manual
www.milestonesys.com 34 About LPR cameras
o Vehicle speed in km/h: Shutter time in seconds = 1 second / (11 × max vehicle speed in
kilometers per hour)
o Vehicle speed in mph: Shutter time in seconds = 1 second / (18 × max vehicle speed in
miles per hour)
where / denotes "divided by" and × denotes "multiplied by."
The following table provides guidelines for recommended camera shutter speeds at different vehicle
speeds:
Shutter time
in seconds
Max. vehicle
speed in
kilometers
per hour
Max. vehicle
speed
in miles per hour
1/50 4 2
1/100 9 5
1/200 18 11
1/250 22 13
1/500 45 27
1/750 68 41
1/1000 90 55
1/1500 136 83
1/2000 181 111
1/3000 272 166
1/4000 363 222
Physical environment
When mounting and using cameras for LPR, note the following environmental factors:

Much light: Too much light in the environment can lead to overexposure or smear.
o Overexposure is when images are exposed to too much light, resulting a in a burnt-out
and overly white appearance. To avoid overexposure it is recommended that you use a
camera with a high dynamic range and/or use an auto-iris lens. Iris is the adjustable
opening (a.k.a. aperture) used for controlling the amount of light coming through a lens. Iris
thus has a significant effect on the exposure of images.