Functional Limitations Of Traffic Sign Recognition, Detailed Information - GF54.30-P-0021-01A
Model all (4xWD)
with code 513 (Road sign recognition system)
Model all (CAR)
with code 504 (Speed sign recognition)
Model all (CAR)
with code 513 (Road sign recognition system)
Overview
This document contains information on:
- General
- Function
- Unknown traffic signs
- Highway entry/exit signs
- Changing traffic signs
- Changing traffic signs without circular ring
- Horizontal angle of vision of multifunction camera
- Resolution of multifunction camera
- Design of back-end sections of commercial vehicles
- Signage on back-end sections of commercial vehicles
- No entry signs
- Warning for red traffic lights
- Warning for stop signs
- DIGITAL LIGHT
General
Speed sign or traffic sign recognition evaluates the information on traffic signs and interprets its meaning. Here, functional restrictions of the traffic sign recognition may occur due to different factors.
Function
Below is a list of situations in which the pictures recorded by the multifunction camera cannot be evaluated and cannot be used for display.
Unknown traffic signs
Only traffic signs that comply with the requirements of the Vienna Convention on Road Traffic Signs are recognized.
Highway entry/exit signs
Speed limits marked by town/village entry and town/village exit signs or by freeway start and finish signs are not recorded. These traffic signs however, are filed through the road definition feature (e.g. freeway) in the digital navigation map. The digital road map must however, be up-to-date and the navigation system must be free of faults.
Example illustration of highway entry and exit signs
Changing traffic signs
Electronically actuated variable traffic signs may be missed or interpreted incorrectly. In the event of changing traffic signs that are actuated by pulses or flashes, there may be difference to the picture recording's permanent cycle time, depending on the actuated frequency of the changing traffic signs. As a result only fragments of the changing traffic signs will be recognized.
If the image cannot be uniquely identified as a traffic sign, the speed value that is stored in the digital navigation map is then shown.
Example illustration of changing traffic signs
Changing traffic signs without circular ring
To enable the detection of changing traffic signs on which the outer circular ring is missing, special detectors have been implemented in the multifunction camera. This type of display is mainly used in The Netherlands and Belgium.
Example illustration of changing traffic signs without circular ring
Horizontal angle of vision of multifunction camera
The horizontal angle of vision of the multifunction camera is limited. Traffic signs erected immediately after junctions into which the vehicle is turning may be missed by the multifunction camera.
Example illustration of horizontal angle of vision of multifunction camera
Resolution of multifunction camera
The resolution of the multifunction camera is limited. Traffic signs on wide or multilane roads may be missed as they do not attain the size required for clear identification in the evaluation window of the multifunction camera.
The sensitivity and dynamics of the multifunction camera are limited. This results in traffic signs not being recognized under the following conditions:
- Traffic signs with low contrast
- Extreme oncoming lights or lights from the rear
- Low levels of lighting, darkness
- Soiling of windshield in area of multifunction camera
- Camera fogged up, damaged or concealed
The focus and alignment of the multifunction camera are fixed. As a result recorded objects are represented with a movement blur depending on the exposure time.
This movement blur and sensitivity of the multifunction camera limit its usefulness at night. The result of the fixed focus and static alignment is that the traffic signs to be recorded must be completely visible in a small observation time window.
Example illustration of resolution of multifunction camera
Design of back-end sections of commercial vehicles
Unfavorably designed back-end sections of commercial vehicles may be interpreted as derestriction signs by mistake.
Example illustration of design of back-end sections of commercial vehicles
Signage on back-end sections of commercial vehicles
Signage on the back-end section of commercial vehicles may be interpreted as traffic signs by mistake.
Example illustration of signage on back-end sections of commercial vehicles
No entry signs
This warning will only be issued in a vehicle speed range between 15 and 100 km/h.
Example illustration of signposting for no entry signs
Warning for red traffic lights
The warning is only issued up to a vehicle speed of approx. 70 km/h.
The following conditions must also be met:
- Multiple traffic lights are detected.
- All traffic lights detected are red.
- At least one of the red traffic lights detected is located on the front passenger side next to your own lane.
- The traffic lights have the following signal sequence (from top to bottom): red, yellow, green.
Example illustration of warning for red traffic lights
Warning for stop signs
The warning is only issued up to a vehicle speed of approx. 70 km/h.
If several different signs are detected, no warning can be issued.
Example illustration of warning for stop signs
DIGITAL LIGHT
Depending on the country involved, the functions may be restricted in the event of any deviating legal requirements.
The system will automatically adjust to the applicable regulations when the vehicle crosses a border.
The system is also only active when the light switch is in the "AUTO" position and high beam is switched on.
Example illustration of DIGITAL LIGHT