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

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

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

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

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

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

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

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

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

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

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

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