You have taken the following light measurements within a Cisco TelePresence environment with the endpoint
powered off:
Facial lighting: 220 lux
Shoulder lighting: 500 lux
Room wall lighting: 120 lux to 300 lux
Which of the following statements are correct? (Choose three.)
A.
The facial lighting is too low.
B.
The facial lighting is too high.
C.
The shoulder lighting is too low.
D.
The shoulder lighting is too high.
E.
The room lighting is too low.
F.
The room wall lighting is too high.
G.
The room wall lighting is too varied.
Explanation:
The shoulder lighting is too high, and the room wall lighting is too high and too varied. Lux is a measurement of
the intensity of a light that strikes a surface. If you do not have a lux meter, you can calculate lux by using the
following formula:
lux = (lumens / meters2)
Lumens is a measurement of the amount of light that is emitted from a light source. A wall that is 3 meters
away from an 1800lumen light source would have a lux value of 200:
lux = (1800 / 32) = (1800 / 9) = 200
Facial lighting is measured by holding a light meter at the person’s face and pointing it toward the camera? this
is called vertical plane lighting. In a Cisco TelePresence environment, facial lighting should be from 200 to 400
lux by using indirect lighting and with the endpoint off. In this scenario, the facial lighting is measured at 220 lux,
which is within Cisco’s recommended parameters.
Shoulder lighting is measured by pointing the light meter at the ceiling; this is called horizontal plane lighting.
Shoulder lighting should not exceed two times the value of the facial lighting. In this scenario, the shoulder
lighting is measured at 500 lux, which is more than twice the facial lighting value of 220 lux.
Facial and shoulder lighting measurements should always be taken with the Cisco TelePresence endpoint off.
The integrated lighting of the Cisco TelePresence endpoint will provide approximately 100 lux. Room lighting
should be equal to or less than the facial lighting and should not vary more than 100 lux within the room. In this
scenario, the highest room wall lighting value is 300 lux, which is more than the facial lighting value of 220 lux.
In addition, the room wall lighting varies by 180 lux. A dimming lighting control system should be used to
provide consistent lighting throughout the environment. Because direct lighting can cause shadowing and glare,
Cisco recommends that indirect lighting be used in Cisco TelePresence environments.Cisco: Cisco TelePresence Room Design Guide: Indirect Lighting (PDF)