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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Class of hierarchical subband coders developed primarily for compression of image data at video rates. Coders offer good performance with limited computational complexity and with flexibility inherent in subband decomposition.
Class of hierarchical subband coders developed primarily for compression of image data at video rates. Offers good performance with limited computational complexity and with flexibility inherent in subband decomposition. Particular subband decomposition chosen for coders appears to hide large quantitative errors effectively, largely because decomposition occurs along two-dimensional spatial-frequency-domain boundaries resembling spatial-frequency-domain curves of constant sensitivity of human visual system. Curves found approximately diamond-shaped: thus, low-pass filtering for reduction of data ideally involves nonrectangular passbands.
This video presents Tracking and Data Relay Satellite and Goddard Space Flight Center involvement.
This demonstration video produced by and for the Goddard Space Flight Center Television facility shows some of the capabilities of this state of the art facility that are available to projects at Goddard.
The objective of this project was to develop methods and application procedures to measure displacement and strain fields during the structural testing of aerospace components using paint speckle in conjunction with the Video Image Correlation (VIC) system.
The idea of synchronizing multiple video recordings to some type of 'range' time has been tried to varying degrees of success in the past. Combining this requirement with existing time code standards (SMPTE) and the new innovations in desktop multimedia however, have afforded an opportunity to increase the flexibility and usefulness of such efforts without adding costs over the traditional data recording and reduction systems. The concept described can use IRIG, GPS or a battery backed internal clock as the master time source. By converting that time source to Vertical Interval Time Code or Longitudinal Time Code, both in accordance with the SMPTE standards, the user will obtain a tape that contains machine/computer readable time code suitable for use with editing equipment that is available off-the-shelf. Accuracy on playback is then determined by the playback system chosen by the user. Accuracies of +/- 2 frames are common among inexpensive systems and complete frame accuracy is more a matter of the users' budget than the capability of the recording system.
In this video, several examples of electromagnetic field and surface-current animation sequences are shown to demonstrate the visualization capabilities of the EM-ANIMATE computer program. These examples show the animation of total and scattered electric near fields from test bodies of a flat plate, a corner reflector, and a sphere. These test cases show the electric-field behavior caused by different scattering mechanisms through the animation of electromagnetic data from the EM-ANIMATE routine.
This research project is intended to develop an efficient system for reliably transmitting image and video data over low bit rate noisy channels. The basic ideas behind the proposed approach are the following: employ statistical-based image modeling to facilitate pre- and post-processing and error detection, use spare redundancy that the source compression did not remove to add robustness, and implement coded modulation to improve bandwidth efficiency and noise rejection. Over the last six months, progress has been made on various aspects of the project. Through our studies of the integrated system, a list-based iterative Trellis decoder has been developed. The decoder accepts feedback from a post-processor which can detect channel errors in the reconstructed image. The error detection is based on the Huber Markov random field image model for the compressed image. The compression scheme used here is that of JPEG (Joint Photographic Experts Group). Experiments were performed and the results are quite encouraging. The principal ideas here are extendable to other compression techniques. In addition, research was also performed on unequal error protection channel coding, subband vector quantization as a means of source coding, and post processing for reducing coding artifacts. Our studies on unequal error protection (UEP) coding for image transmission focused on examining the properties of the UEP capabilities of convolutional codes. The investigation of subband vector quantization employed a wavelet transform with special emphasis on exploiting interband redundancy. The outcome of this investigation included the development of three algorithms for subband vector quantization. The reduction of transform coding artifacts was studied with the aid of a non-Gaussian Markov random field model. This results in improved image decompression. These studies are summarized and the technical papers included in the appendices.
A new series of video measurements were made of the phenomenon provisionally termed the cloud-to-stratosphere (CS) event, an electrical discharge extending to great heights above thunderstorm tops. This new series of measurements were accomplished by properly positioning a sensor, the Xybion model ISS 225 low-light monochrome imaging system with a C-mount fl.8 manual zoom lens, and training it on the appropriate portion of the sky above a distant thunderstorm complex mean Fort Collins, Colorado. The resulting images are currently undergoing intensive analysis. Some tentative conclusions are given. Cloud-to-stratosphere events occur far more frequently than previously suspected and are perhaps a ubiquitous aspect of many larger convective systems. Cloud-to-stratosphere events are also of substantial horizontal extent, on the order of tens of kilometers in some cases.
Designs of video random-access memory (VRAM) integrated circuits operating under control by external logic circuits simplified according to concept of combining two memory operations performed separately heretofore. Eliminates need for DRAM-refresh timers and counters, reducing amount of circuitry needed to control VRAM thereby reducing time needed to design VRAM. Simplification also reduces time needed to redesign DRAM-refresh logic circuitry when adapting VRAM design to another VRAM for which timing specifications different. Concept can be applied to VRAM clocking data out to display unit continuously.
Enhanced DPCM video compression algorithm utilizes non-uniform quantizer, non-adaptive predictor, and multi-level Huffman coder to substantially reduce data rate below that achievable with conventional DPCM. Images reconstructed without noticeable degradation.
The first day of the STS-69 flight is highlighted in this video. Shown are the prelaunch and launch activities and the in-orbit SPARTAN-201 satellite pre-deployment checkout of the robot arm in the shuttle's bay. The flight crew consisted of Cmdr. Dave Walker, Pilot Ken Cockrell, and Mission Specialists Jim Voss, Jim Newman, and Mike Gernhardt. Earth views of cloud cover are included.
In this report, we present our study on multiprocessor implementation of a MPEG2 encoding algorithm. First, we compare two approaches to implementing video standards, VLSI technology and multiprocessor processing, in terms of design complexity, applications, and cost. Then we evaluate the functional modules of MPEG2 encoding process in terms of their computation time. Two crucial modules are identified based on this evaluation. Then we present our experimental study on the multiprocessor implementation of the two crucial modules. Data partitioning is used for job assignment. Experimental results show that high speedup ratio and good scalability can be achieved by using this kind of job assignment strategy.
The goal of this research effort was to study methods of video image correlation and electronic shearography for nondestructive evaluation of aerospace components. Methods of physical load application must be developed before interrogations with these methods may be used to qualify hardware. To that end, inspection procedures were developed for a variety of aerospace components and material systems. Experiments were also conducted from which the relationship between the control settings of the electronic shearography apparatus may be related to flaw detectability. A short feasibility study was conducted to determine the applicability of electronic shearography to the determination of the stress intensity factor of a Mode 1 crack tip by measurement of the localized zone of three dimensional plasticity
Subpixel digital video image correlation (SDVIC) technique for measuring in-plane displacements on surfaces of objects under loads, without contact. Used for analyses of experimental research specimens or actual service structures of virtually any size or material. Only minimal preparation of test objects needed, and no need to isolate test objects from minor vibrations or fluctuating temperatures. Technique implemented by SDVIC software, producing color-graduated, full-field representations of in-plane displacements and partial derivatives with respect to position along both principal directions in each image plane. From representations, linear strains, shear strains, and rotation fields determined. Written in C language.
Endoscopic video-imaging system generates panoramic image of part of wall of cavity surrounding tip of probe inserted in cavity. Not necessary to rotate probe to obtain panoramic image. If simple inspection without measurement required, device called "cylindrical light ring" mounted on probe to illuminate scene. Different illumination device used when required to measure distance of wall of cavity from cylindrical axis of probe. System used, for example, to inspect inner surface of tube, passage, or manifold located deep within engine or other complex structure.
Monocular video imaging and image-data-processing system views robotic vehicle and measures position and orientation of vehicle in terms of position and orientation of colored cylinder mounted on vehicle. Data-processing subsystem determines position of cylinder from viewing angle and size of colored cylinder in image. System also follows innovative approach in determining orientation of cylinder.
This paper introduces a new approach to coding ultrasound video, the intended application being very low bit rate coding for transmission over low cost phone lines. The method exploits both the characteristic noise and the quasi-periodic nature of the signal. Data compression ratios between 250:1 and 1000:1 are shown to be possible, which is sufficient for transmission over ISDN and conventional phone lines. Preliminary results show this approach to be promising for remote ultrasound examinations.