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Flat Refractive Geometry for Underwater Size Measurements

Discover the innovative flat refractive geometry approach for underwater size measurements. This method, developed by Treibitz, Schechner, and Singh, provides a practical and accurate solution for geometry calibration in underwater imaging systems. The system offers an improved way to measure sizes and distances in water, overcoming the limitations of traditional methods. With a focus on accuracy and practicality, this system's calibration process ensures precise measurements in various underwater environments. Dive into the world of underwater geometry with this groundbreaking technology.

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Flat Refractive Geometry for Underwater Size Measurements

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  1. Flat Refractive Geometry Tali Treibitz, Yoav Y. Schechner Technion, Israel Hanumant Singh Woods Hole Oceanographic Institute

  2. /192 Into Water Through Flat Window

  3. /193 Geometrical Applications Size measurements Underwater stereo Harvey & Shortis Brandou et al.

  4. /194 Prior Art- a Single Viewpoint Model Just a magnification effect: B. Skerry and H. Hall, ‘02 Webster, ‘98 Lavest et al, ECCV ‘00 scubageek.com Other diving and underwater photography literature Treibitz, Schechner & Singh, Flat Refractive Geometry

  5. /195 Prior Art- a Single Viewpoint Model radial distortion, e.g. 3D distortion Harvey & Sortis, MTS J. ’02 Bryant et al, ACRA ’00 Pessel et al., WSCG ’03 Kwon & Casebolt, Sports Biomechanics ‘06 Negahdaripour & Firoozfan, IEEE J. Oceanic Eng. ’05 in a water tank Treibitz, Schechner & Singh, Flat Refractive Geometry

  6. /196 Other non-single viewpoint systems: Sturm et al., Imaging beyond the pinhole camera,’06 Swaminathan et al., IJCV’06 Grossberg & Nayar, IJCV’05 Pajdla, IJCV’02 Peleg et al., PAMI’01 Single Viewpoint? No! interface physical lens position apparent viewpoint? apparent viewpoint? Treibitz, Schechner & Singh, Flat Refractive Geometry

  7. /197 A Radial Distortion? No! interface single viewpoint model error distortion cannot be corrected lens visible objects are occluded errors can reach dozens of pixels Treibitz, Schechner & Singh, Flat Refractive Geometry

  8. /199 air water Treibitz, Schechner & Singh, Flat Refractive Geometry

  9. /1910 Prior Light Field Calibration: non-parametric • General • Used in Aquaria • Requires a few frames • Difficult outside the lab Grossberg & Nayar, IJCV ’05 Sturm & Ramalingam, ECCV ’04 Zongker et al., SIGGRAPH ’99 Fuchs et al., EGSR ’08 Kutulakos & Steger, IJCV ’07 Narashiman et al., ICCV ’05

  10. Parameter Fitting /1911 known size known distance   lens measured projection Treibitz, Schechner & Singh, Flat Refractive Geometry

  11. /1912 Our Calibration Method Known inputs: An underwater experiment size , distance Constraint:

  12. /1913 Result- a Ray Map • Applications: • Stereo • Measurements • Geometrical applications Imaging System

  13. Size Measurement From Known Distances /1914 our method ground truth single viewpoint  underestimation * not at the calibration distances Treibitz, Schechner & Singh, Flat Refractive Geometry

  14. /1915 Rays in the Imaging System iris Treibitz, Schechner & Singh, Flat Refractive Geometry

  15. /1916 Rays in the Imaging System iris a caustic surface Treibitz, Schechner & Singh, Flat Refractive Geometry

  16. Caustics of the Flat Interface System /1917 interface a camera with a full FOV of 100° in air lens Treibitz, Schechner & Singh, Flat Refractive Geometry

  17. /1918 Caustics of the Flat Interface System A closed-form solution: the system has a single viewpoint Treibitz, Schechner & Singh, Flat Refractive Geometry

  18. Flat Refractive Geometry • Non-single viewpoint system • Old models  significant errors • Correct physics-based model & caustics • Calibration of true geometry: accurate, practical, in-situ Tali Treibitz, Yoav Y. Schechner & Hanumant Singh

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