RESUMEN
We propose an automated method for detecting neutral points in the sunlit sky. Until now, detecting these singularities has been done manually. Results are presented that document the application of this method on a limited number of polarimetric images of the sky captured with a camera and rotating polarizer. The results are significant because a method for automatically detecting the neutral points may aid in the determination of the solar position when the sun is obscured and may have applications in meteorology and pollution detection and characterization.
RESUMEN
Imaging laser radar (ladar) systems have been developed for automatic target identification in surveillance systems. Ladar uses the range value at the target pixels to estimate the target's 3-D shape and identify the target. For targets in clutter and partially hidden targets, there are ambiguities in determining which pixels are on target that lead to uncertainties in determining the target's 3-D shape. An improvement is to use the polarization components of the reflected light. We describe the operation and preliminary evaluation of a polarization diverse imaging ladar system. Using a combination of intensity, range, and degree of polarization, we are better able to identify and distinguish the target from other objects of the same class.
Asunto(s)
Algoritmos , Inteligencia Artificial , Interpretación de Imagen Asistida por Computador/métodos , Imagenología Tridimensional/métodos , Rayos Láser , Reconocimiento de Normas Patrones Automatizadas/métodos , Radar , Refractometría/métodos , Análisis por Conglomerados , Aumento de la Imagen/métodos , Almacenamiento y Recuperación de la Información/métodos , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
A technique for automatic detection of targets from their infrared signature's state-of-polarization vector is described. The bounds on the Bayesian total probability of errors are estimated from the observed Stokes vector imagery and used as metrics for separating targets from background clutter. The performance of the proposed approach for objects under various geometries is studied in terms of receiver operating characteristic curves. The new results, which have been obtained from data from the U.S. Air Force's Infrared Modeling and Analysis polarimetric infrared simulation tool, indicate the usefulness of polarimetric infrared signatures for the automatic detection of small targets.
RESUMEN
A substantial number of patients present with medically refractory angina who are not candidates for angioplasty or bypass surgery. The creation of channels between the myocardium and the ventricular blood pool has been performed after thoracotomy with excellent relief of symptoms but has been associated with high perioperative mortality. We investigated the safety of a nonoperative, percutaneous technique for channel creation. Twenty-seven patients with angina and coronary anatomy not amenable to revascularization with coronary angioplasty or bypass surgery underwent percutaneous transluminal myocardial revascularization (PTMR). Energy from a Holmium:yttrium-aluminum-garnet (YAG) laser was directed through a fiber enclosed in a catheter to the ventricular myocardium creating channels between the blood pool and the myocardium. On average, 17 +/- 4 channels were formed per patient. There were no procedure-related deaths, episodes of tamponade, or other complications except for an increase in creatine phosphokinase in 1 patient. Immediately after the procedure, there was no worsening of regional wall motion function in any patient, but rather improvement in some. All patients were discharged alive after a hospital stay of 1.8 +/- 1.5 days. Mean Canadian Cardiovascular Society functional class declined from 3.6 +/- 0.5 before the procedure to 0.65 +/- 0.8 at 30 days after the procedure (p < 0.01). For 12 patients eligible for 6-month follow-up, mean functional class was 0.94 +/- 0.97. At 6-month stress testing, 9 of these 12 had no electrocardiographic evidence of ischemia. Thus, PTMR can be performed safely in the cardiac catheterization laboratory with a complication rate lower than that reported in surgical series and with excellent near-term symptomatic relief. The long-term effect of PTMR on mortality and relief of angina as well as its safety and effectiveness compared with the surgical approach remains to be defined.