American Audio VELOCITY - REV 4-05 Betriebsanleitung PDF herunterladen (Seite 121)

METRO RAIL DESIGN CRITERIA SECTION 9 / SYSTEMS

DE304.09 9-116 Revision 4 : 05/09/12

Metro Baseline Re-Baseline: 04/29/10

- Shall use with Gamma correction (0.45 to 1.0, adjustable) and shall have

an automatic light range that results in not more than ±3 dB video output

change with a 1000:1 change in scene luminance. There shall be no

sensor damage in the image sensors within the specified light range.

- Be housed in corrosion-resistant, vandal-resistant environmental

enclosure with reflection inhibiting, shatterproof glass or polycarbonate

viewing port. Enclosures shall be weatherproof when installed in

exposed environment.

- Be equipped with sunshades when used outdoors as required to prevent

unwanted reflections into lenses. Consideration to object/target clarity

will be evaluated when applying sunshades to camera housings.

Cameras located in an environment that is subject to rain shall be sealed

to prevent moisture infiltration and build-up.

- Camera housings and mounting apparatus including hardware shall

consist of anti-corrosive (rust-proof) material.

- Lenses: Focal length and Fields of View (FOV)

 The selection of lenses will be dictated by the field-of-view to be covered by

each camera, as well as by the size of the camera's detector. For cameras

placed to record images at a point of transactions, such as a front of fare

machine or parking approach , the area of interest (e.g., face, license plate)

should cover approximately 15 percent or more of the camera's field-of-view

(based on the recommended minimum resolution).

Examples:

1. For an average human head that is six-inches wide, a three-foot-wide

field-of-view will meet this guideline.

2. For a license plate width of approximately 12 inches, a six-foot-wide

field-of-view is sufficient.

 The focal length necessary to achieve an approximately three-foot-wide

field-of-view for a given detector size and camera-to-subject distance is

provided in Table below. The camera must be in focus at the position of this

subject.

Approximate Focal length (in mm) needed for a 3 wide Field of view (in feet)

Distance to

Subject (in feet)

2 feet 5 feet 10 feet 15 feet 20 feet 30 feet

Camera Optical

format (in inches)

¼” 2.3 mm 5.9 mm 11.7 mm 17.6 mm 23.5 mm 35.2 mm

1/3” 3.1 mm 7.8 mm 15.7 mm 23.5 mm 31.3 mm 47 mm

½” 4 mm 10.1 mm 20.2 mm 30.3 mm 40.4 mm 60.7 mm

Differences in the units used to describe these resolution recommendations are

due to the differences in the industry recommended practices used to describe

them.

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