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At least 991 records · Page 55

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NASA NTRS1978

Diagnosis of cutaneous thermal burn injuries by multispectral imaging analysis

Special photographic or television image analysis is shown to be a potentially useful technique to assist the physician in the early diagnosis of thermal burn injury. A background on the medical and physiological problems of burns is presented. The proposed methodology for burns diagnosis from both the theoretical and clinical points of view is discussed. The television/computer system constructed to accomplish this analysis is described, and the clinical results are discussed.

Anselmo, V. J.↗

NASA NTRS1979

Low-level processing for real-time image analysis

A system that detects object outlines in television images in real time is described. A high-speed pipeline processor transforms the raw image into an edge map and a microprocessor, which is integrated into the system, clusters the edges, and represents them as chain codes. Image statistics, useful for higher level tasks such as pattern recognition, are computed by the microprocessor. Peak intensity and peak gradient values are extracted within a programmable window and are used for iris and focus control. The algorithms implemented in hardware and the pipeline processor architecture are described. The strategy for partitioning functions in the pipeline was chosen to make the implementation modular. The microprocessor interface allows flexible and adaptive control of the feature extraction process. The software algorithms for clustering edge segments, creating chain codes, and computing image statistics are also discussed. A strategy for real time image analysis that uses this system is given.

Eskenazi, R.↗

NASA NTRS1979

Fixed-base simulation study of decoupled longitudinal controls during approach and landing of a medium jet transport in the presence of wind shear

The use of decoupled longitudinal controls during the approach and landing of a typical twin-engine jet transport in the presence of wind shear was studied. The simulation included use of a localizer and flight director to capture and maintain a 3 deg glide slope. The pilot then completed the landing by using visual cues provided below an altitude of 200 m by closed-circuit television and a terrain model. The decoupled controls used constant prefilter and feedback gains to provide steady state decoupling of flight path angle, pitch angle, and forward velocity. The use of the decoupled control system improved pilot performance during the approach and at touchdown in the presence of wind shears. The pilots preferred the decoupled controls and rated the task 1 to 3 increments better on a pilot rating scale, depending on wind conditions, than was the case when conventional controls were used.

Miller, G. K., Jr.↗

NASA NTRS1977

The robot's eyes - Stereo vision system for automated scene analysis

Attention is given to the robot stereo vision system which maintains the image produced by solid-state detector television cameras in a dynamic random access memory called RAPID. The imaging hardware consists of sensors (two solid-state image arrays using a charge injection technique), a video-rate analog-to-digital converter, the RAPID memory, and various types of computer-controlled displays, and preprocessing equipment (for reflexive actions, processing aids, and object detection). The software is aimed at locating objects and transversibility. An object-tracking algorithm is discussed and it is noted that tracking speed is in the 50-75 pixels/s range.

Williams, D. S.↗

NASA NTRS1978

Information systems

Space-derived information is the principal product of our civilian space program. Associated data from earth-orbital and planetary spacecraft will exceed the equivalent of some 500 television pictures per second during the 1980's. Cost-effective management of this data flood requires a new look at NASA's overall information systems. Advanced technologies being pursued by industry and NASA could provide order-of-magnitude reductions in data-handling costs and times to permit a massive increase in the use of space-acquired data for both individual and national needs. This paper discusses attendant thrusts in efficient data acquisition, instrument pointing, real-time data management, and low-cost data distribution. Current and planned technology activities in these areas and their anticipated impact on future space missions are described.

Kurzhals, P. R.↗

NASA NTRS1978

Viking Orbiter observations of the Mars opposition effect

Viking television photography of two dust storms that occurred during the Viking extended mission are used to show that the enhancement of the opposition effect at short wavelengths reported during the 1967 and 1969 oppositions does not appear to be an atmospheric effect, as previously suggested. The brightness changes near 0 deg phase as seen by the Viking Orbiters during the June 15, 1977, dust storm are modeled, yielding first-order aerosol parameters that tend to suppress the opposition effect in violet light. It is proposed that the opposition-effect phenomenon, if real, might be characterized by assuming a surface covered with a particle microstructure of the same single-scattering albedo found for the June dust-storm aerosols, combined with a lunar phase function (macrostructure).

Thorpe, T. E.↗

NASA NTRS1978

Potential digitization/compression techniques for Shuttle video

The Space Shuttle initially will be using a field-sequential color television system but it is possible that an NTSC color TV system may be used for future missions. In addition to downlink color TV transmission via analog FM links, the Shuttle will use a high resolution slow-scan monochrome system for uplink transmission of text and graphics information. This paper discusses the characteristics of the Shuttle video systems, and evaluates digitization and/or bandwidth compression techniques for the various links. The more attractive techniques for the downlink video are based on a two-dimensional DPCM encoder that utilizes temporal and spectral as well as the spatial correlation of the color TV imagery. An appropriate technique for distortion-free coding of the uplink system utilizes two-dimensional HCK codes.

Habibi, A.↗

NASA NTRS1979

A photometric determination of twists in three early-type galaxies

Detailed photometric data have been obtained for three early-type galaxies by using the Cerro Tololo 1.5-m telescope and an SEC television camera. The aim of this photometry is to gain further accurate information on the occurrence of twists in such galaxies; i.e., on any variations with radius of the position angle of the major axes of the isophotes. The results of the photometry are: (1) the finding of no detectable twist within the bulge of the S0 galaxy NGC 5102; (2) confirmation of a substantial twist (about 10 deg) in the inner portion of the E3 galaxy IC 1459; and (3) determination of a moderate twist (about 5 deg) within the E4 galaxy NGC 4697, possibly too small to have been previously detected. If such moderate twists should turn out to be common in elliptical galaxies, the suspicion of triaxiality for most such galaxies would be enhanced.

Williams, T. B.↗

NASA NTRS1979

A detached experiment carrier aids adaptation of experiments from sounding rockets to Space Shuttle

The detached experiment carrier (DEC) system aids the adaptation of small, low-weight experiments to Space Shuttle missions. The carrier system consists of the detached experiment carrier (free-flyer), a command station at the Orbiter aft station, and a flight support station in the Orbiter payload bay. The carrier is a compact vehicle that is radio controlled by the Shuttle crew. It uses control television, command, and cold gas propulsion systems to deploy experiments from and later rendezvous with the Orbiter. The carrier propulsion system also maintains the attitude control required during experiment execution. Results of engineering investigation, analysis, component design and development, and testing indicate that the DEC system concept is practical. Results of preliminary engineering investigations, including maneuvering system handling qualities and television/telemetry display formats, indicate that the concept of flying the DEC 'out of' and 'into' the Orbiter payload bay is both safe and practical for small, compact free-flyer deployment and retrieval. This paper describes the carrier system, its operations, and potential applications.

Ritz, W. F.↗

NASA NTRS1978

Comparison of video fields and frames for transform compression

Because of the interlaced television scan, the two fields that form an interlaced video frame are generated 1/60 of a second apart. If the two fields are compressed independently, the correlation between adjacent lines is unused. The transmission rate can be reduced by using a field memory to form an interlaced frame. Four test images were processed as fields and as interlaced frames, using both theoretical and experimental compression designs. For comparable mean-square error and subjective appearance, field compression requires about one-half bit per sample more than frame compression. However, the overall transmission rate - the number of bits per image times the number of images per second - is more meaningful than the number of bits per sample. When transform compression at low transmission rates merges the adjacent lines, frame compression becomes similar to field repeating, and the memory can be reduced.

Jones, H. W., Jr.↗

NASA NTRS1979

Robotic vision

Robotic vision, involving the use of a vision system to control a process, is discussed. Design and selection of active sensors employing radiation of radio waves, sound waves, and laser light, respectively, to light up unobservable features in the scene are considered, as are design and selection of passive sensors, which rely on external sources of illumination. The segmentation technique by which an image is separated into different collections of contiguous picture elements having such common characteristics as color, brightness, or texture is examined, with emphasis on the edge detection technique. The IMFEX (image feature extractor) system performing edge detection and thresholding at 30 frames/sec television frame rates is described. The template matching and discrimination approach to recognize objects are noted. Applications of robotic vision in industry for tasks too monotonous or too dangerous for the workers are mentioned.

Williams, D. S.↗

NASA NTRS1979

Construction in space - Toward a fresh definition of the man/machine relation

The EVA (extravehicular activity) project forming part of the space construction process is reviewed. The manual EVA constuction, demonstrated by the crew of Skylab 3 by assembling a modest space structure in the form of the twin-pole sunshade, is considered, indicating that the experiment dispelled many doubts about man's ability to execute routine and contingency EVA operations. Tests demonstrating the feasibility of remote teleoperator rendezvous, station keeping, and docking operations, using hand controllers for direct input and television for feedback, are noted. Future plans for designing space construction machines are mentioned.

Watters, H. H.↗

NASA NTRS1979

Auroral mechanisms and morphology

The present review is concerned with observations, analysis of observations and theoretical work as related to the understanding of the aurora. The ground-based observations reviewed include (1) auroral imagery, both by television and all-sky camera; (2) gross magnetic variations indicative of ionospheric currents; (3) VLF hiss observations; and (4) effects of high-energy electron impact measured through cosmic radio noise absorption and by observations of bremsstrahlung X-ray from balloons. Spectroscopic observations, observation of micropulsation activity and auroral radar observations are not included, since they seem to provide less direct diagnostic information on the basic auroral mechanism. Incoherent scatter radar observations are utilized to the extent they provide information on ionospheric currents and electric fields. Satellite observations are included to the extent they provide information on the aurora or useful clues to auroral mechanisms. Barium injection experiments in the auroral zone are also considered.

Swift, D. W.↗

NASA NTRS1979

Visual observations from space

Visual observations from space reveal a number of fascinating natural phenomena of interest to meteorologists and aeronomists, such as aurorae, airglow, aerosol layers, lightning, and atmospheric refraction effects. Other man-made radiation, including city lights and laser beacons, are also of considerable interest. Of course, the most widely used space observations are of the large-scale weather systems viewed each day by millions of people on their local television. From lower altitudes than the geostationary meteorological satellite orbits, obliques and overlapping stereo views are possible, allow height information to be obtained directly, often a key element in the use of the photographs for research purposes. However, this note will discuss only the less common observations mentioned at the beginning of this paragraph.

Garriott, O. K.↗

NASA NTRS1979

The TIROS-N high resolution infrared radiation sounder

The high-resolution infrared radiation sounder (HIRS/2) was developed and flown on the Television and Infrared Observation Satellite, N Series (TIROS-N) as one means of obtaining atmospheric vertical profile information. The HIRS/2 receives visible and infrared spectrum radiation through a single telescope and selects 20 narrow spectral channels by means of a rotating filter wheel. A passive radiant cooler provides an operating temperature of 106.7K for the HgCdTe and InSb detectors while the visible detector operates at instrument frame temperature. Low noise amplifiers and digital processing provide 13 bit data for spacecraft data multiplexing and transmission. The qualities of system performance that determine sounding capability are the dynamic range of data collection, the noise equivalent radiance of the system, the registration of the air columns sampled in each channel, and the ability to upgrade the calibration of the instrument to maintain the performance standard throughout life. The basic performance of the instrument in test is described. Early orbital information from the TIROS-N launched on October 13, 1978 are given and some observations on system quality are made.

Koenig, E. W.↗

NASA NTRS1980

Crossed-grid charge locator

Circuit locates center of cloud of charge on wire grid to within 6.5 micrometers. Wires in vicinity of charge cloud develop voltages that are processed by priority encoders to develop coarse and fine position codes. Device is used with microchannel plate amplifier in X-ray photon detectors, electron microscopes, and closed-circuit television.

Harrison, D. C.↗

NASA NTRS1980

Detecting contaminants by ultraviolet photography

Relatively high ultraviolet absorptivity of most organics as compared to metal is suggested as basis for detecting traces of contamination. By photographing metal surface in ultraviolet light, contaminants that might otherwise interfere with adhesion of surface coatings, or with welding or brazing, could be detected and removed. Real time monitoring of cleaning process is also possible if ultraviolet sensitive television camera is used instead of photographic film.

Neiswander, D. W.↗

NASA NTRS1981

Compressing TV-image data

Compressing technique calculates activity estimator for each segment of image line. Estimator is used in conjunction with allowable bits per line, N, to determine number of bits necessary to code each segment and which segments can tolerate truncation. Preprocessed line data are then passed to adaptive variable-length coder, which selects optimum transmission code. Method increases capacity of broadcast and cable television transmissions and helps reduce size of storage medium for video and digital audio recordings.

Hilbert, E. E.↗