Publications of the Jet Propulsion Laboratory, January through December 1974

Formalized technical reporting is described and indexed, which resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. The five classes of publications included are technical reports, technical memorandums, articles from the bimonthly Deep Space Network Progress Report, special publications, and articles published in the open literature. The publications are indexed by author, subject, and publication type and number

Using dispersion measures for determining block-size in motion estimation

Video compression techniques remove temporal redundancy among frames and enable high compression efficiency in coding systems. Reduction of temporal redundancy is achieved by motion compensation. In turn, motion compensation requires motion estimation. Block matching is perhaps the most reliable and robust technique for motion estimation in video coding. However, block matching is computational expensive. Different approaches have been proposed in order to improve block matching motion estimation accuracy and efficiency. In this paper a block-matching strategy for motion estimation is introduced. In the proposed approach the size of matching block is adapted according to the variability of the matching areas. That is, the block-size is constrained by variations of the image intensity. The variability is assessed using two variability measures: the variance and the mean absolute deviation. Results of computer experiments aimed at validating the performance of the proposed approach are also reported

Geobase Information System Impacts on Space Image Formats

As Geobase Information Systems increase in number, size and complexity, the format compatability of satellite remote sensing data becomes increasingly more important. Because of the vast and continually increasing quantity of data available from remote sensing systems the utility of these data is increasingly dependent on the degree to which their formats facilitate, or hinder, their incorporation into Geobase Information Systems. To merge satellite data into a geobase system requires that they both have a compatible geographic referencing system. Greater acceptance of satellite data by the user community will be facilitated if the data are in a form which most readily corresponds to existing geobase data structures. The conference addressed a number of specific topics and made recommendations

The automatic sensing and analysis of 3-D surface points from visual scenes

technical reportDescribed are the design and implementation of a new range-measuring sensing device and an associated software algorithm for constructing surface descriptions of arbitrary three-dimensional objects from single or multiple views. The sensing device, which measures surface points from objects in its environment, is a computer-controlled, random-access, triangulating rangefinder with a mirror-deflected laser beam and revolving disc detectors. The algorithm developed processes these surface points and generates, in a deterministic fashion, complete surface descriptions of all encountered objects. In its processing, the algorithm also detects parts of objects for which there is insufficient data, and can supply the sensing device with the control parameters needed to successfully measure the uncharted regions. The resulting object descriptions are suitable for use in a number of areas, such as computer graphics, where the process of constructing object definitions has heretofore been very tedious. Together with the sensing device, this approach to object description can be utilized in a variety of scene analysis and pattern recognition applications which involve interaction with "real world", three-dimensional objects

Computerised stereoscopic measurement of the human retina

The research described herein is an investigation into the problems of obtaining useful clinical measurements from stereo photographs of the human retina through automation of the stereometric procedure by digital stereo matching and image analysis techniques. Clinical research has indicated a correlation between physical changes to the optic disc topography (the region on the retina where the optic nerve enters the eye) and the advance of eye disease such as hypertension and glaucoma. Stereoscopic photography of the human retina (or fundus, as it is called) and the subsequent measurement of the topography of the optic disc is of great potential clinical value as an aid in observing the pathogenesis of such disease, and to this end, accurate measurements of the various parameters that characterise the changing shape of the optic disc topography must be provided. Following a survey of current clinical methods for stereoscopic measurement of the optic disc, fundus image data acquisition, stereo geometry, limitations of resolution and accuracy, and other relevant physical constraints related to fundus imaging are investigated. A survey of digital stereo matching algorithms is presented and their strengths and weaknesses are explored, specifically as they relate to the suitability of the algorithm for the fundus image data. The selection of an appropriate stereo matching algorithm is discussed, and its application to four test data sets is presented in detail. A mathematical model of two-dimensional image formation is developed together with its corresponding auto-correlation function. In the presense of additive noise, the model is used as a tool for exploring key problems with respect to the stereo matching of fundus images. Specifically, measures for predicting correlation matching error are developed and applied. Such measures are shown to be of use in applications where the results of image correlation cannot be independently verified, and meaningful quantitative error measures are required. The application of these theoretical tools to the fundus image data indicate a systematic way to measure, assess and control cross-correlation error. Conclusions drawn from this research point the way forward for stereo analysis of the optic disc and highlight a number of areas which will require further research. The development of a fully automated system for diagnostic evaluation of the optic disc topography is discussed in the light of the results obtained during this research

Técnicas de procesamiento de imágenes estereoscópicas

En este trabajo se presenta una revisión de métodos para correspondencia estereoscópica con el fin de tratar de encontrar la mejor de las posibles además de tratar de mejorarla. Existen diversos métodos en la literatura para llevar a cabo la correspondencia estereoscópica, siendo generalmente necesario el diseño de nuevos métodos con el fin de mejorar los resultados cuando las técnicas se aplican a entornos reales de exterior. Este es el objetivo del presente trabajo con el fin de aplicar los métodos a entornos reales. Se aprovechan las bondades de los algoritmos estudiados para la realización del nuevo método buscado. Se utiliza técnicas de filtrado comunes tales como la media o la mediana junto con un método de enfriamiento simulado(simulated annealing) y otro de propagación que se ha creado como aporte de investigación. Los resultados de estas dos técnicas se comparan con los métodos clásicos previamente seleccionados. [ABSTRACT] This work presents a revision of classical methods in stereovision matching. This is intended for selecting the best approach and to improve its performance. There are several methods for conducting stereo vision matching in the literature, being usually necessary to design new methods to be applied in real outdoor environments. This is the main goal of this work. This is the objective of this work, which presents different techniques for stereo vision, which takes advantage of the benefits of the algorithms used to perform a new method to improve outcome. It uses common filtering techniques such as mean or median along a simulated annealing technique and a spread that has been created as a research contribution. The results of these two techniques are compared with classical methods which are previously selected

Automatic face recognition using stereo images

Face recognition is an important pattern recognition problem, in the study of both natural and artificial learning problems. Compaxed to other biometrics, it is non-intrusive, non- invasive and requires no paxticipation from the subjects. As a result, it has many applications varying from human-computer-interaction to access control and law-enforcement to crowd surveillance. In typical optical image based face recognition systems, the systematic vaxiability arising from representing the three-dimensional (3D) shape of a face by a two-dimensional (21)) illumination intensity matrix is treated as random vaxiability. Multiple examples of the face displaying vaxying pose and expressions axe captured in different imaging conditions. The imaging environment, pose and expressions are strictly controlled and the images undergo rigorous normalisation and pre-processing. This may be implemented in a paxtially or a fully automated system. Although these systems report high classification accuracies (>90%), they lack versatility and tend to fail when deployed outside laboratory conditions. Recently, more sophisticated 3D face recognition systems haxnessing the depth information have emerged. These systems usually employ specialist equipment such as laser scanners and structured light projectors. Although more accurate than 2D optical image based recognition, these systems are equally difficult to implement in a non-co-operative environment. Existing face recognition systems, both 2D and 3D, detract from the main advantages of face recognition and fail to fully exploit its non-intrusive capacity. This is either because they rely too much on subject co-operation, which is not always available, or because they cannot cope with noisy data. The main objective of this work was to investigate the role of depth information in face recognition in a noisy environment. A stereo-based system, inspired by the human binocular vision, was devised using a pair of manually calibrated digital off-the-shelf cameras in a stereo setup to compute depth information. Depth values extracted from 2D intensity images using stereoscopy are extremely noisy, and as a result this approach for face recognition is rare. This was cofirmed by the results of our experimental work. Noise in the set of correspondences, camera calibration and triangulation led to inaccurate depth reconstruction, which in turn led to poor classifier accuracy for both 3D surface matching and 211) 2 depth maps. Recognition experiments axe performed on the Sheffield Dataset, consisting 692 images of 22 individuals with varying pose, illumination and expressions

On Computer Stereo Vision with Wire Frame Models

Coordinated Science Laboratory changed its name from Control Systems LaboratoryShould have been numbered UILU-ENG 77-2252, and that number may have been distributed on some copies.Joint Services Electronics Program / DAAB-07-72-C-0259Ope

Obtención de mapas de profundidad densos mediante visión activa por movimiento controlado de una cámara : Aplicación a tareas de reconocimiento

En este trabajo se presenta una aproximación novedosa al problema de obtención de información tridimensional de una escena a partir de distintas vistas de la misma. El montaje sobre el que se ha realizado la validación experimental de los algoritmos desarrollados es del tipo hand-eye por ser un tipo de montaje suficientemente contrastado en la literatura y con claras aplicaciones industriales. Entre ellas están las de prototipado rápido, agarre o construcción de entornos virtuales para teleoperación. No obstante, los algoritmos obtenidos son fácilmente realizables sobre otro tipo de sistemas tales como robots móviles. En este caso las aplicaciones en navegación visual y levantamiento de mapas de entornos desconocidos son claramente identificables. La consecución del objetivo final ha supuesto la investigación y la obtención de resultados reseñables en distintas áreas. Ha sido necesario el desarrollo de un proceso de calibración del sistema en el que se hacen aportaciones a la calibración de cámaras con fuerte distorsión radial. La estructura tridimensional de los objetos de la escena se ha obtenido de manera incremental. La investigación en este campo ha dado como fruto la evolución de un método clásico (MCE) de obtención de distancias por estereoscopía y el desarrollo de otro novedoso (RRD). La determinación de la posición de la siguiente reconstrucción incremental ha hecho necesario el estudio de las diferentes estrategias presentes en la literatura para la solución del problema de determinación de la siguiente mejor vista (NBV). Como resultado se presenta el desarrollo de un nuevo algoritmo NBV especialmente adaptado al empleo de cámaras como elemento de toma de datos. El trabajo concluye presentando los resultados obtenidos al utilizar los resultados obtenidos en un sistema de reconocimiento tridimensional de objetos. Este tipo de aplicación se ha elegido por su gran exigencia en la calidad de los datos de entrada y la clara aplicación práctica de un sistema de este tipo