Additional surface sensor for verifying visibility/fog Alert travelers to unsafe conditions (via VMS) Prioritize which cameras are displayed to TMC (or to web users) Alert maintenance crews when a camera is covered/blocked MIT Lincoln Laboratory
Goals • Automatically Measure Visibility and Detect Fog Utilizing Standard Visible Camera Imagery Visibility(East): 1 km : +0.1km Visibility(km) Roadway Conditions: Partially Snow Covered Precipitation: Moderate Snow
>10 >5 1-5 0.0-1.0
Visibility(West): 0.2 km : +0.1km Fog: Heavy Fog : Thickening
Fog Description Heavy Moderate Light FHWA-FY01 Review-3 RGH 9/24/2001
Roadway Conditions: Clear Precipitation: None MIT Lincoln Laboratory
How far can I see ?
Esposito Hangar: 0.4km Taconic Ridge Line: 6.7km
Hangar: 0.2km
Near Ridge: 2.1km
Road: 0.030km FHWA-FY01 Review-4 RGH 9/24/2001
Gas Tanks: 0.042km
Gas Tanks: 0.042km MIT Lincoln Laboratory
Algorithm Flow Chart GPS
Satellite Visibility Algorithm
Image Capture
Lighting Correction
Edge Detection Fog Algorithm
Composite Image Generator
Edge Detection
Trend Algorithm
Image Registration Edges of interest
(30 day average)
Normalized Edge Extraction Unexpected Edges
Users
Sensor Problems
Weather Detection
Placeholders for future development FHWA-FY01 Review-5 RGH 9/24/2001
MIT Lincoln Laboratory
Visibility Algorithm
Normalized Edge Extraction
Edges of interest
Edge Mean
Assumptions: • Stationary camera • Initially only daylight images • Focus on visibility < 10km (and particularly < 1km) • Known min and max range
Edge Median Unexpected Edges
Image Power Visibility
Status
Edge Power Max Edge Power
- Value - Direction - Confidence Camera
Consensus
FHWA-FY01 Review-6 RGH 9/24/2001
- Status
MIT Lincoln Laboratory
Multiple Determination Techniques Hanscom Camera 2/2/2000 through 3/9/2000 during daylight Edge Detection Image Mean
Stddev
Power
140
12000
100
10000
80
8000
60
6000
40
4000
20
2000
Power
Mean & Stddev (Grayscale)
120
14000
Mean R=0.68 Stdev R=0.63 Power R=0.61
0 100
1000
0 10000
Visibility (meters)
FHWA-FY01 Review-7 RGH 9/24/2001
MIT Lincoln Laboratory
Video Visibility – Preliminary Tests Video Estimated Visibility (km) > 10 70% CSI for all ranges, >90% CSI
