1. Driving assistance: automatic fog detection and measure of the visibility distance
Vehicle-Infrastructure-Driver Interactions Research Unit
Driving assistance: Automatic fog detection and measure of the visibility distance
Nicolas HAUTIERE PhD Student
Didier AUBERT
Researcher

2. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Presentation Overview
Introduction
Fog, light and vision
Fog effects on road vision
Modeling visual effects
Algorithm overview
Results
Conclusion
Nicolas HAUTIERE – Didier AUBERT

3. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Introduction
Measuring the atmospheric visibility:
Estimates the operation range of on-board perception sensors.
Constitutes a driving assistance.
This work is part of the ARCOS project.
Nicolas HAUTIERE – Didier AUBERT

4. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Fog, light and vision
Fog microstructure
Fog is a concentration of water droplets suspended in the air, bringing visibility below one kilometer.
Light scattering
The daylight is scattered by fog droplets in all directions. This effect is described by an extinction coefficient k.
Visibility impairment
The fog reduces distant contrasts. This effect is described by the meteorological visibility: the greatest distance at which a black object of suitable dimensions can be seen.
Applications envisagées
Activation/désactivation des feux de anti-brouillard
Information du conducteur sur la distance de visibilité
Information des véhicules situés en amont d’une zone de faible visibilité
Adaptation automatique de la vitesse selon les conditions météorologiques
Information vers les systèmes de traitement vidéo embarqués sur la qualité des images
Nicolas HAUTIERE – Didier AUBERT

5. Fog effects on road vision
Driving assistance: automatic fog detection and measure of the visibility distance
Fog effects on road vision
Attenuation effect
e-kd1
e-kd2
e-kd
surface
Halo effect
Veiling effect

6. Modeling fog visual effects
Driving assistance: automatic fog detection and measure of the visibility distance
Modeling fog visual effects
Koschmieder’s law (1924)
Distance of the object to the camera
Extinction coefficient of fog
Apparent luminance of the object
Fog luminance at the horizon
Intrinsic luminance of the object
International Commission on Illumination (CIE)
Nicolas HAUTIERE – Didier AUBERT

7. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Algorithm overview
Koschmieder’s law
At the inflection point
Resolving the equation
Measure of the median luminance
Computation of a band of measure
Derivation of the curve of luminance
Computation of ROI
Computation of the visibility distance
Extraction of an inflection point
Nicolas HAUTIERE – Didier AUBERT

8. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Results
Low dense fog – Vehicle following
Nicolas HAUTIERE – Didier AUBERT

9. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Results
Dense fog – Vehicle crossing
Nicolas HAUTIERE – Didier AUBERT

10. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Results
Dense fog – Curve
Nicolas HAUTIERE – Didier AUBERT

11. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Conclusion
This original method has the following advantages:
detects the presence of fog and measures the meteorological distance of visibility,
is based on a physical model of fog,
indicates if it is temporary inoperative,
needs only the presence of the road and the sky in the image to work,
is real time performed,
works with a single camera.
Nicolas HAUTIERE – Didier AUBERT

12. Nicolas HAUTIERE – Didier AUBERT
Driving assistance: automatic fog detection and measure of the visibility distance
Questions ?
Nicolas HAUTIERE – Didier AUBERT