CCTV Knowledge 5 — Questions and Answers
Question 1: What is the purpose of a 'de-warping' algorithm in fisheye camera systems?
- To correct the barrel distortion of a 360° fisheye image into a flat, rectilinear view (Correct answer)
- To reduce digital noise in low-light images
- To stabilize video from cameras mounted in vibrating environments
- To convert color footage to black and white for storage efficiency
Correct answer: To correct the barrel distortion of a 360° fisheye image into a flat, rectilinear view
De-warping software mathematically corrects the curved distortion inherent in fisheye lenses, converting the circular panoramic image into a flat, viewable perspective.
Question 2: In a CCTV system, what is meant by 'covert surveillance'?
- Surveillance using cameras visible to the public to deter crime
- Surveillance conducted using hidden or disguised cameras without subjects' awareness (Correct answer)
- Remote viewing of camera feeds over a VPN connection
- Monitoring conducted exclusively by law enforcement agencies
Correct answer: Surveillance conducted using hidden or disguised cameras without subjects' awareness
Covert surveillance uses concealed cameras to monitor subjects without their knowledge, and is subject to strict legal regulations that vary by jurisdiction.
Question 3: What does the term 'latency' refer to in the context of IP camera video transmission?
- The delay between when an event occurs and when it appears on the monitor (Correct answer)
- The time required to retrieve archived footage from the NVR
- The interval between scheduled recording sessions
- The response time of the PTZ camera motor
Correct answer: The delay between when an event occurs and when it appears on the monitor
Latency is the delay introduced by encoding, network transmission, and decoding, and is a critical consideration in applications requiring real-time monitoring and immediate response.
Question 4: Which standard governs the minimum image resolution requirements for automatic license plate recognition (ALPR/ANPR) cameras?
- The camera must achieve at least 50 pixels on the height of the license plate character (Correct answer)
- The camera must record at 4K resolution
- The camera must use a global shutter sensor
- The camera must capture at least 60 fps to freeze fast-moving plates
Correct answer: The camera must achieve at least 50 pixels on the height of the license plate character
ALPR systems typically require a minimum of 50 pixels on the height of a license plate character to reliably read plate numbers, regardless of the camera's overall resolution.
Question 5: What is the primary advantage of using fiber optic cable to transmit CCTV video signals?
- Lower cost compared to coaxial cable
- Immunity to electromagnetic interference and ability to transmit signals over much longer distances (Correct answer)
- Easier to install without specialized tools
- Compatibility with all legacy analog cameras
Correct answer: Immunity to electromagnetic interference and ability to transmit signals over much longer distances
Fiber optic cable is immune to EMI/RFI interference and supports transmission distances of several kilometers, making it ideal for large campus or industrial CCTV installations.
Question 6: In PTZ camera operation, what is the function of 'preset positions'?
- Factory-default settings for image quality that reset after a power cycle
- Pre-programmed pan, tilt, and zoom positions that the camera can move to instantly on command (Correct answer)
- The maximum zoom and tilt limits set to prevent mechanical damage
- Default recording schedules assigned by the NVR
Correct answer: Pre-programmed pan, tilt, and zoom positions that the camera can move to instantly on command
PTZ presets allow operators to store specific pan, tilt, and zoom positions so the camera can return to those exact viewpoints instantly at the press of a button or via automation.
Question 7: What is 'continuous recording' mode in a CCTV DVR/NVR, and what is its main drawback?
- Recording only when motion is detected — drawback is that slow intruders may be missed
- Recording at all times regardless of activity — drawback is significantly higher storage consumption (Correct answer)
- Recording triggered by alarm inputs only — drawback is dependence on peripheral sensors
- Recording at reduced frame rate during off-hours — drawback is lower image quality at night
Correct answer: Recording at all times regardless of activity — drawback is significantly higher storage consumption
Continuous recording captures footage 24/7 regardless of activity, which ensures no events are missed but consumes far more storage than motion-triggered or scheduled recording modes.
CCTV Knowledge 5
What is the purpose of a 'de-warping' algorithm in fisheye camera systems?