Mr. Lorenzo A. Rivamonte Profile

Lorenzo A. Rivamonte

Electronics Engineer

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Bottlenose dolphin vision

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Proceedings Article | 24 February 2009 Paper

Bottlenose dolphin iris asymmetries enhance aerial and underwater vision

Andre Rivamonte

Proceedings Volume 7163, 716321 (2009) https://doi.org/10.1117/12.804433

KEYWORDS: Iris, Visualization, Eye models, Eye, Cornea, Water, Visual process modeling, Ray tracing, Enhanced vision, Retina

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When the iris of the Bottlenose dolphin (Tursiops truncatus) contracts it constrains the path of light that can focus onto the two areas of the retina having a finer retinal mosaic. Under high ambient light conditions the operculum of the iris shields the lens and forms in the process two asymmetrically shaped, sized and positioned slit pupils. Tracing rays of light in the reverse direction through the pupils from the retinal regions associated with higher resolution confirm behaviorally observed preferred aerial and underwater viewing directions. In the forward and downward viewing direction, the larger temporal pupil admits light that is focused by the weakly refractive margin of a bifocal lens onto the temporal area centralis compensating for the addition of the optically strong front surface of the cornea in air. A schematic dolphin eye model incorporating a bifocal lens offers an explanation for a dolphin's comparable visual acuities in air and water for both high and low ambient light conditions. Comparison of methods for curve fitting psychometric ogive functions to behavioral visual acuity and spectral sensitivity data are discussed.

Proceedings Article | 1 October 1990 Paper

Resolution and signal-to-noise measurement of U.S. Army night-vision goggles

Lorenzo Rivamonte

Proceedings Volume 1290, (1990) https://doi.org/10.1117/12.20967

KEYWORDS: Oscilloscopes, CCD cameras, Video, Image analysis, Goggles, Image quality, Cameras, Head-mounted displays, Image resolution, Modulation transfer functions

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The ability to quantitatively characterize the performance of night vision goggles (NVG) is being investigated because the present method of resolution evaluation relies on an imprecise, subjective pass/fail judgement by a trained observer viewing a test pattern. Variation in an observer's training, experience, psychological state, decision bias and visual acuity strongly affect his or her decision when required to decide if a marginal pair of goggles passes or fails. The controversy concerning the increase in commercial and military helicopter accidents involving NVG indicates a need to determine if 1) the use of defective or marginal NVG is a contributing factor to the increase in accidents or 2) the apparent correlation between NVG and accidents is simply due to the increased use of NVG in an expanded and inherently more dangerous flight envelope. The U.S. Army TMDE Support Group (USATSG) has developed instrumentation to augment the AN/3895 TS test set that presents high and low light level resolution targets to AN/PVS-5, AN/AVS-6 and AN/PVS-7 NVG. The NVG Resolution Augmentation to the AN/3895 TS presented here can also quantitatively measure image quality of other image producing systems which are normally viewed, adjusted or inspected by a human observer. The NVG Resolution Augmentation features a custom electronic circuit which provides a user-friendly interface between a commercially available CCD camera, monitor and oscilloscope. USATSG's Army Primary Standards Laboratory at the Redstone Arsenal is presently studying the possibility of a new measurement service by investigating various CCD camera/lens combinations in order to characterize a machine vision standard observer. A characterized image analysis system would enable absolute as well as relative measurements of image quality.

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