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Chromatic Framework for Vision in Bad Weather

Chromatic Framework for Vision in Bad Weather. Srinivasa G. Narasimhan and Shree K. Nayar Computer Science Department Columbia University IEEE CVPR Conference June 2000, Hilton Head Island, USA Sponsors: ONR MURI , NSF. Dense Fog. Noon Haze. B. B. R. R. G. G.

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Chromatic Framework for Vision in Bad Weather

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  1. Chromatic Framework for Vision in Bad Weather Srinivasa G. Narasimhan and Shree K. Nayar Computer Science Department Columbia University IEEE CVPR Conference June 2000, Hilton Head Island, USA Sponsors: ONR MURI , NSF

  2. Dense Fog Noon Haze B B R R G G The Colors of Bad Weather Clear Day B R G

  3. General Color Framework for Analysis of Bad Weather Images OUR GOAL : Prior Work • Overviews : Middleton 1952 , McCartney 1976 • Haze : Hulburt 1946 , Hidy 1972 • Fog : Koshmeider 1924 , George 1951 , Myers 1968 • Vision : • Cozman & Krotkov 1997 - Depth Cues from Iso-Intensities • Nayar & Narasimhan 1999 - Complete Structure ; Restricted weather conditions

  4. ( Allard, 1876 ) ( Koschmieder, 1924 ) Diffuse Skylight Sunlight Diffuse Ground Light E E Direct Transmission Airlight Direct Transmission and Airlight Models Object Observer d

  5. Direct Transmission (True Color ) Airlight (Fog / Haze Color) Model : Dichromatic Atmospheric Scattering Model ( Nayar & Narasimhan, 1999 ) B E R G

  6. Verification : Scene (800 x 600 pixels) Avg. Error (degrees) 0.25 º Foggy Hazy 0.31 º Dichromatic Planes Direct Transmission Color Dichromatic Plane Airlight Color

  7. Plane 2 (Scene Point O) Airlight Color from Planes : Direction of Airlight ( Fog or Haze ) Color Plane 1 (Scene Point X) Weather Condition 1 Weather Condition 2

  8. , , Sky Brightnesses : ( Unknown ) Direct Transmission Ratio Scaled Depth Ratio of Direct Transmissions : Depth of a Scene Point : Sky Brightness Ratio Depth from Unknown Weather Conditions Scattering Coefficients : ( Unknown )

  9. Direct Transmission Ratio : Direct Transmission Ratio Direct Transmission Color Dichromatic Plane Airlight Color

  10. Relative Airlight Depth of a Scene Point Relation Between Sky Brightnesses Sky Brightnesses Direct Transmission Color Dichromatic Plane Airlight Color

  11. Recovered Structure Fog 2 + Noise Fog 1 + Noise Results with a Synthetic Scene Color Patches Rotated Structure

  12. 1.5 2.5 2.0 0.5 1.0 3.0 Noise 0 Estimated 200.02 200.65 201.4 200.23 200.96 202.1 200 401.1 403.6 400.02 400.4 400.60 405.8 Estimated 400 Depth Error (%) 0.0 0.63 0.36 0.79 0.53 0.93 0.54 Actual Values = Simulation Results 0.5 1.5 2.5 1.0 2.0 3.0 Noise 0 Estimated 100.02 100.65 103.23 100.55 101.26 104.84 100 258.2 260.13 255.02 255.4 256.61 263.45 Estimated 255 Depth Error (%) 0.0 0.82 0.42 0.89 0.58 0.96 0.76 Actual Values =

  13. Computed Depth Map Structure from Two Weather Conditions Scene under two different Hazy Conditions

  14. Computed Depth Map Structure from Two Weather Conditions Scene under two different Foggy Conditions

  15. Minimum Time to Collision Min First Collision with Color Boundary True Color Recovery - Color Cube Boundary Algorithm 1 2 3 B O G R

  16. Computed True Color True Color Recovery Scene under two different Foggy Conditions ( Brightened )

  17. Color Framework for Vision in Bad Weather Summary • Airlight Color from Dichromatic Planes • Scene Depth from Dichromatic Constraints • True Color fromColor Boundary Constraint

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