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NASA NTRS1989

Rotorcraft deceleration to hover using image-based guidance

Rotorcraft operating in hostile environment fly at low altitudes to minimize exposure to the defensive weapons arrayed against them. The development of intelligent guidance commands at low altitudes requires the integration of conventional guidance with the information provided by the sensor on relative position between the vehicle and local terrain or obstacles. Deceleration to hover (DTH) is one of the common maneuvers executed by a rotorcraft. The authors describe the integration of DTH guidance logic with an image-based scheme to estimate the hover point. The performance of such a system is affected by parameters of the guidance and by navigation and image processing algorithms. Results are presented on the effect of the parameters on system performance.

Sridhar, Banavar↗

NASA NTRS1990

Making Topographical Maps From SAR and Flood-Gauge Data

Collection of computer programs processes image data obtained by synthetic-aperture radar (SAR) along with measurements of water levels taken at selected points on ground to generate three-dimensional maps of surveyed terrain. Information in maps presented in variety of useful ways suited to study of such phenomena as flooding, damage caused by floods, flow of nutrients from forests to river and marine ecosystems, and effects of subsidence of ground or of rising sea levels.

Imhoff, Marc Lee↗

NASA NTRS1990

Ultrasonic Imaging Of Deep Arteries

Swept-frequency sound replaces pulsed sound. Ultrasonic medical instrument produces images of peripheral and coronary arteries with resolutions higher and at depths greater than attainable by previous ultrasonic systems. Time-delay-spectrometry imager includes scanning, image-processing, and displaying equipment. It sweeps in frequency from 0 to 10 MHz in 20 ms, pauses for 5 ms, and repeats sweep. Intended for use in noninvasive detection and measurement of atherosclerotic lesions.

Rooney, James A.↗

NASA NTRS1989

Summaries of the thematic conferences on remote sensing for exploration geology

The Thematic Conference series was initiated to address the need for concentrated discussion of particular remote sensing applications. The program is primarily concerned with the application of remote sensing to mineral and hydrocarbon exploration, with special emphasis on data integration, methodologies, and practical solutions for geologists. Some fifty invited papers are scheduled for eleven plenary sessions, formulated to address such important topics as basement tectonics and their surface expressions, spectral geology, applications for hydrocarbon exploration, and radar applications and future systems. Other invited presentations will discuss geobotanical remote sensing, mineral exploration, engineering and environmental applications, advanced image processing, and integration and mapping.

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NASA NTRS1989

CCD TV focal plane guider development and comparison to SIRTF applications

It is expected that the SIRTF payload will use a CCD TV focal plane fine guidance sensor to provide acquisition of sources and tracking stability of the telescope. Work has been done to develop CCD TV cameras and guiders at Lick Observatory for several years and have produced state of the art CCD TV systems for internal use. NASA decided to provide additional support so that the limits of this technology could be established and a comparison between SIRTF requirements and practical systems could be put on a more quantitative basis. The results of work carried out at Lick Observatory which was designed to characterize present CCD autoguiding technology and relate it to SIRTF applications is presented. Two different design types of CCD cameras were constructed using virtual phase and burred channel CCD sensors. A simple autoguider was built and used on the KAO, Mt. Lemon and Mt. Hamilton telescopes. A video image processing system was also constructed in order to characterize the performance of the auto guider and CCD cameras.

Rank, David M.↗

NASA NTRS1989

Optimal focal-plane restoration

Image restoration can be implemented efficiently by calculating the convolution of the digital image and a small kernel during image acquisition. Processing the image in the focal-plane in this way requires less computation than traditional Fourier-transform-based techniques such as the Wiener filter and constrained least-squares filter. Here, the values of the convolution kernel that yield the restoration with minimum expected mean-square error are determined using a frequency analysis of the end-to-end imaging system. This development accounts for constraints on the size and shape of the spatial kernel and all the components of the imaging system. Simulation results indicate the technique is effective and efficient.

Reichenbach, Stephen E.↗

NASA NTRS1989

Computer-aided boundary delineation of agricultural lands

The National Agricultural Statistics Service of the United States Department of Agriculture (USDA) presently uses labor-intensive aerial photographic interpretation techniques to divide large geographical areas into manageable-sized units for estimating domestic crop and livestock production. Prototype software, the computer-aided stratification (CAS) system, was developed to automate the procedure, and currently runs on a Sun-based image processing system. With a background display of LANDSAT Thematic Mapper and United States Geological Survey Digital Line Graph data, the operator uses a cursor to delineate agricultural areas, called sampling units, which are assigned to strata of land-use and land-cover types. The resultant stratified sampling units are used as input into subsequent USDA sampling procedures. As a test, three counties in Missouri were chosen for application of the CAS procedures. Subsequent analysis indicates that CAS was five times faster in creating sampling units than the manual techniques were.

Cheng, Thomas D.↗

NASA NTRS1988

The 2nd Symposium on the Frontiers of Massively Parallel Computations

Programming languages, computer graphics, neural networks, massively parallel computers, SIMD architecture, algorithms, digital terrain models, sort computation, simulation of charged particle transport on the massively parallel processor and image processing are among the topics discussed.

Mills, Ronnie↗

NASA NTRS1990

The 1990 Goddard Conference on Space Applications of Artificial Intelligence

The papers presented at the 1990 Goddard Conference on Space Applications of Artificial Intelligence are given. The purpose of this annual conference is to provide a forum in which current research and development directed at space applications of artificial intelligence can be presented and discussed. The proceedings fall into the following areas: Planning and Scheduling, Fault Monitoring/Diagnosis, Image Processing and Machine Vision, Robotics/Intelligent Control, Development Methodologies, Information Management, and Knowledge Acquisition.

Rash, James L.↗

NASA NTRS1990

Spatial cross-correlation of Antarctic Sea ice and seabed topography

A time series of derived sea ice concentrations as observed about Antarctica by the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) satellite in 1983 is considered. The degree of spatial cross correlation between these data and seabed topography is quantified. The approach is to implement a statistical image processing filter designed to extract local patterns of spatial cross correlation over the entire sea ice field as it undergoes daily changes. Throughout the sea ice, it was found that large scale variations in sea ice concentration correlate systematically with variations in the topography of the seabed. Generally speaking, high concentrations of sea ice occur over deep ocean, whereas areas of encavement, early dissipation and polynya formation develop over topographic features of high elevation. The latter was studied in detail with respect to the features Maud Rise, Astrid Ridge and the continental shelf in the Cosmonaut and Ross Seas. In each case, it is shown that an encavement in sea ice, a polynya, or both develops in the vicinity of the feature in question. As these results are quantified in terms of spatial cross correlation, a potential role is inferred for seabed topography in such fluctuations in the sea ice about Antarctica.

Deveaux, Richard D.↗

NASA NTRS1990

Detecting perceptual groupings in textures by continuity considerations

A generalization is presented for the second derivative of a Gaussian D(sup 2)G operator to apply to problems of perceptual organization involving textures. Extensions to other problems of perceptual organization are evident and a new research direction can be established. The technique presented is theoretically pleasing since it has the potential of unifying the entire area of image segmentation under the mathematical notion of continuity and presents a single algorithm to form perceptual groupings where many algorithms existed previously. The eventual impact on both the approach and technique of image processing segmentation operations could be significant.

Greene, Richard J.↗

NASA NTRS1989

A tesselated probabilistic representation for spatial robot perception and navigation

The ability to recover robust spatial descriptions from sensory information and to efficiently utilize these descriptions in appropriate planning and problem-solving activities are crucial requirements for the development of more powerful robotic systems. Traditional approaches to sensor interpretation, with their emphasis on geometric models, are of limited use for autonomous mobile robots operating in and exploring unknown and unstructured environments. Here, researchers present a new approach to robot perception that addresses such scenarios using a probabilistic tesselated representation of spatial information called the Occupancy Grid. The Occupancy Grid is a multi-dimensional random field that maintains stochastic estimates of the occupancy state of each cell in the grid. The cell estimates are obtained by interpreting incoming range readings using probabilistic models that capture the uncertainty in the spatial information provided by the sensor. A Bayesian estimation procedure allows the incremental updating of the map using readings taken from several sensors over multiple points of view. An overview of the Occupancy Grid framework is given, and its application to a number of problems in mobile robot mapping and navigation are illustrated. It is argued that a number of robotic problem-solving activities can be performed directly on the Occupancy Grid representation. Some parallels are drawn between operations on Occupancy Grids and related image processing operations.

Elfes, Alberto↗

NASA NTRS1989

Force/torque and tactile sensors for sensor-based manipulator control

The autonomy of manipulators, in space and in industrial environments, can be dramatically enhanced by the use of force/torque and tactile sensors. The development and future use of a six-component force/torque sensor for the Hermes Robot Arm (HERA) Basic End-Effector (BEE) is discussed. Then a multifunctional gripper system based on tactile sensors is described. The basic transducing element of the sensor is a sheet of pressure-sensitive polymer. Tactile image processing algorithms for slip detection, object position estimation, and object recognition are described.

Vanbrussel, H.↗

NASA NTRS1988

The influence of processor focus on speckle correlation statistics for a Shuttle imaging radar scene of Hurricane Josephine

The surface wave field produced by Hurricane Josephine was imaged by the L-band SAR aboard the Challenger on October 12, 1984. Exponential trends found in the two-dimensional autocorrelations of speckled image data support an equilibrium theory model of sea surface hydrodynamics. The notions of correlated specular reflection, surface coherence, optimal Doppler parameterization and spatial resolution are discussed within the context of a Poisson-Rayleigh statistical model of the SAR imaging process.

Tilley, David G.↗

NASA NTRS1989

Thematic Mapper and field investigations at the intersection of the Death Valley and Garlock fault zones, California

Analysis of processed images and detailed field investigations have provided significant information concerning the late-Pliocene and Quaternary evolution of the intersection of the Garlock and Death Valley fault zones. The imagery was used to determine patterns of sedimentation and age relationships on alluvial fans and to determine the geometry, styles of deformation, and relative ages of movements on major and minor faults in the study area. The field investigation often confirmed the inferences drawn from the images and provided additional tectonic and geomorphologic data about the Quaternary deformation of the region. All the data gathered in the course of this project support the contention that the Garlock fault zone terminates in the Avawatz Mountains and that the Death Valley fault zone continues south of the intersection for at least 50 km, forming the eastern boundary of the Mojave province.

Brady, Roland H., III↗

NASA NTRS1989

Radiometric calibration of Landsat Thematic Mapper Thermal Band

Radiometric calibration of satellite-acquired data is essential for quantitative scientific studies, as well as for a variety of image-processing applications. This paper describes a multiyear, on-orbit radiometric calibration of the Landsat Thematic Mapper (TM) Band 6 conducted at DOE's Pacific Northwest Laboratory. Numerous Landsat TM scenes acquired and analyzed included day and night coverages at several geographical locations over several seasons. Concurrent with Landsat overpasses, thermal field and local meteorological (surface and radiosonde) measurements were collected. At-satellite (uncorrected) radiances and temperatures for water and nonwater land cover were compared to ground truth (GT) measurements after making adjustments for atmospheric (using LOWTRAN), mixed-pixel, and emissivity effects. Results indicate that, for both water and nonwater features, TM Band 6 average corrected temperature determinations using local radiosonde data to adjust for atmospheric effects, and using appropriate emissivities, are within 1.0 C of GT temperature values. Temperatures of water pixels derived from uncorrected TM Band 6 data varied roughly between 1 and 3 C of ground truth values for water temperatures ranging between 4 and 24 C. Moreover, corrections using nonlocal and noncoincident radiosonde data resulted in errors as large as 12 C. Corrections using the U.S. Standard Atmosphere gave temperature values within 1 to 2 C of GT. The average uncertainty for field instruments was + or - 0.2 C; average uncertainty for Landsat TM corrected temperature determinations was + or - 0.4 C.

Wukelic, G. E.↗

NASA NTRS1990

Images of the AMPTE artificial comets

Ground-based low-light-level CCD image observations were conducted of both Active Magnetospheric Particle Tracer Explorer artificial comet experiments. Preliminary image processing and gridding into absolute astronomical coordinates are presented to illustrate the dynamical features of the effects. In both cases, the neutral gas expanded at about 1.4 km/sec. The resultant plasma structures corresponding to the comet's head drifted perpendicularly to the direction of the solar wind at speeds of about 3 km/sec and about 1 km/sec, respectively. For the second comet, B(+) ejection speeds of about 10 km/sec preceded the recoil effect, and downstream accelerations of about 90 m/sec-squared were observed.

Mendillo, Michael↗

NASA NTRS1990

A multisensor approach to sea ice classification for the validation of DMSP-SSM/I passive microwave derived sea ice products

The validation of sea ice products derived from the Special Sensor Microwave Imager (SSM/I) on board a DMSP platform is examined using data from the Landsat MSS and NOAA-AVHRR sensors. Image processing techniques for retrieving ice concentrations from each type of imagery are developed and results are intercompared to determine the ice parameter retrieval accuracy of the SSM/I NASA-Team algorithm. For case studies in the Beaufort Sea and East Greenland Sea, average retrieval errors of the SSM/I algorithm are between 1.7 percent for spring conditions and 4.3 percent during freeze up in comparison with Landsat derived ice concentrations. For a case study in the East Greenland Sea, SSM/I derived ice concentration in comparison with AVHRR imagery display a mean error of 9.6 percent.

Steffen, K.↗