Driving assistance: automatic fog detection and measure of the visibility distance

1. Driving assistance: automatic fog detection and measure of the visibility distance Vehicle-Infrastructure-DriverInteractions Research Unit Driving assistance:Automatic fog detection and measureof the visibility distance Didier AUBERT Researcher Nicolas HAUTIEREPhD Student

2. 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. 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. 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. Nicolas HAUTIERE – Didier AUBERT

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

6. Driving assistance: automatic fog detection and measure of the visibility distance Modeling fog visual effects Distance of the object to the camera • Koschmieder’s law (1924) 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. Driving assistance: automatic fog detection and measure of the visibility distance At the inflection point Koschmieder’s law Computation of a band of measure Derivation of the curve of luminance Extraction of an inflection point Computation of the visibility distance Resolving the equation Measure of the median luminance Algorithm overview Computation of ROI Nicolas HAUTIERE – Didier AUBERT

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

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

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

11. 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, • isreal time performed, • works with a single camera. Nicolas HAUTIERE – Didier AUBERT

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