47 Matching Results

Search Results

Advanced search parameters have been applied.

Image Content Engine (ICE)

Description: The Image Content Engine (ICE) is being developed to provide cueing assistance to human image analysts faced with increasingly large and intractable amounts of image data. The ICE architecture includes user configurable feature extraction pipelines which produce intermediate feature vector and match surface files which can then be accessed by interactive relational queries. Application of the feature extraction algorithms to large collections of images may be extremely time consuming and is launched as a batch job on a Linux cluster. The query interface accesses only the intermediate files and returns candidate hits nearly instantaneously. Queries may be posed for individual objects or collections. The query interface prompts the user for feedback, and applies relevance feedback algorithms to revise the feature vector weighting and focus on relevant search results. Examples of feature extraction and both model-based and search-by-example queries are presented.
Date: March 26, 2007
Creator: Brase, J M
Partner: UNT Libraries Government Documents Department

Remote sensing, imaging, and signal engineering

Description: This report discusses the Remote Sensing, Imaging, and Signal Engineering (RISE) trust area which has been very active in working to define new directions. Signal and image processing have always been important support for existing programs at Lawrence Livermore National Laboratory (LLNL), but now these technologies are becoming central to the formation of new programs. Exciting new applications such as high-resolution telescopes, radar remote sensing, and advanced medical imaging are allowing us to participate in the development of new programs.
Date: March 1, 1993
Creator: Brase, J. M.
Partner: UNT Libraries Government Documents Department

A qualitative study of internal wave ship wakes: Dependence on environmental conditions and experimental parameters

Description: For the past several years the UK-US Radar Ocean Imaging Program has conducted a series of field experiments with the primary purpose of gathering real aperture radar (RAR) imagery at low grazing angle of ship-generated internal wave (IW) wakes. The first observations with RAR`s were made in the 1989 Loch Linnhe experiment where it was observed that radar images at low grazing angles (LGA) of approximately six degrees had significantly higher modulation levels than SAR images made at higher grazing angles of 35 - 65 degrees. These initial observations have led to several more experiments designed to verify the phenomenon and to test its dependence on experimental and environmental conditions. A parallel effort began to develop theoretical models of the LGA imaging process. Through this series of experiments we have developed an extensive database of radar imagery and supporting environmental data. The objective of this report is twofold: (1) To describe the database and the associated space of parameters. We will look at the coverage of the parameter space within the database and at areas which should be covered. (2) To take an initial look at the dependence of qualitative modulation strength on the experimental and environmental parameters. This first look will indicate the strongest dependencies which can then be studied in more detail. Section 2 describes the experimental database and Section 3 discusses the parameter space, image quality, and their relationships based on the images in the database. In Section 4 we summarize our conclusions and make recommendations for both future analyses and experiments.
Date: April 24, 1995
Creator: Mullenhoff, C.J. & Brase, J.M.
Partner: UNT Libraries Government Documents Department

Horizontal and Slant-Path Surveillance with Speckle Imaging

Description: A fundamental problem in providing high-quality surveillance images recorded over long horizontal or slant paths is the blurring caused by atmospheric turbulence, which reduces both the resolution and contrast. The objective of the work reported here is to develop a capability for long-range imaging through the atmosphere that is not limited by the atmosphere but only by the fundamental diffraction limit of the optics. This paper describes our recent horizontal and slant-path imaging experiments of point targets and extended scenes as well as simulations of point targets in comparison to experiment. We show the near-diffraction limited resolution results obtained using bispectral speckle-imaging techniques. The experiments were performed with an 8-inch diameter telescope placed either in a field, on a rooftop, or on a hillside and cover ranges of interest from 100 meters up to 10 km. The scenery includes resolution targets, people, vehicles, and other structures.
Date: August 19, 2002
Creator: Carrano, C J & Brase, J M
Partner: UNT Libraries Government Documents Department

Adapting high-resolution speckle imaging to moving targets and platforms

Description: High-resolution surveillance imaging with apertures greater than a few inches over horizontal or slant paths at optical or infrared wavelengths will typically be limited by atmospheric aberrations. With static targets and static platforms, we have previously demonstrated near-diffraction limited imaging of various targets including personnel and vehicles over horizontal and slant paths ranging from less than a kilometer to many tens of kilometers using adaptations to bispectral speckle imaging techniques. Nominally, these image processing methods require the target to be static with respect to its background during the data acquisition since multiple frames are required. To obtain a sufficient number of frames and also to allow the atmosphere to decorrelate between frames, data acquisition times on the order of one second are needed. Modifications to the original imaging algorithm will be needed to deal with situations where there is relative target to background motion. In this paper, we present an extension of these imaging techniques to accommodate mobile platforms and moving targets.
Date: February 5, 2004
Creator: Carrano, C J & Brase, J M
Partner: UNT Libraries Government Documents Department

Wavefront control system for the Keck telescope

Description: The laser guide star adaptive optics system currently being developed for the Keck 2 telescope consists of several major subsystems: the optical bench, wavefront control, user interface and supervisory control, and the laser system. The paper describes the design and implementation of the wavefront control subsystem that controls a 349 actuator deformable mirror for high order correction and tip-tilt mirrors for stabilizing the image and laser positions.
Date: March 1, 1998
Creator: Brase, J. M., LLNL
Partner: UNT Libraries Government Documents Department

Keck adaptive optics: control subsystem

Description: Adaptive optics on the Keck 10 meter telescope will provide an unprecedented level of capability in high resolution ground based astronomical imaging. The system is designed to provide near diffraction limited imaging performance with Strehl {gt} 0.3 n median Keck seeing of r0 = 25 cm, T =10 msec at 500 nm wavelength. The system will be equipped with a 20 watt sodium laser guide star to provide nearly full sky coverage. The wavefront control subsystem is responsible for wavefront sensing and the control of the tip-tilt and deformable mirrors which actively correct atmospheric turbulence. The spatial sampling interval for the wavefront sensor and deformable mirror is de=0.56 m which gives us 349 actuators and 244 subapertures. This paper summarizes the wavefront control system and discusses particular issues in designing a wavefront controller for the Keck telescope.
Date: March 8, 1996
Creator: Brase, J.M.; An, J. & Avicola, K.
Partner: UNT Libraries Government Documents Department

Nonlinear image filtering within IDP++

Description: IDP++, image and data processing in C++, is a set of a signal processing libraries written in C++. It is a multi-dimension (up to four dimensions), multi-data type (implemented through templates) signal processing extension to C++. IDP++ takes advantage of the object-oriented compiler technology to provide ``information hiding.`` Users need only know C, not C++. Signals or data sets are treated like any other variable with a defined set of operators and functions. We here some examples of the nonlinear filter library within IDP++. Specifically, the results of MIN, MAX median, {alpha}-trimmed mean, and edge-trimmed mean filters as applied to a real aperture radar (RR) and synthetic aperture radar (SAR) data set.
Date: February 9, 1995
Creator: Lehman, S.K.; Wieting, M.G. & Brase, J.M.
Partner: UNT Libraries Government Documents Department

Micro-tomography using synchrotron radiation

Description: This paper discusses the results of recent experiments at Stanford Synchrotron Radiation Laboratory (SSRL) and Hamburger Synchrotronstrahlungslabor (HASYLAB) which were designed to explore the feasibility of using synchrotron radiation in high-resolution, computerized, critical-absorption tomography. The results demonstrate that it is possible, using absorption-edge differencing, to identify adjacent elements in the periodic table with high sensitivity. Furthermore, by using the fine structure in the absorption spectra, it is possible to distinguish between regions of different chemical states. Methods of using synchrotron radiation for high-resolution, three-dimensional chemical-state mapping in small samples are discussed.
Date: April 9, 1986
Creator: Johnson, Q.C.; Kinney, J.H.; Bonse, U.; Nichols, M.C.; Nusshardt, R. & Brase, J.M.
Partner: UNT Libraries Government Documents Department

High-resolution CT system for elemental mapping

Description: The performance of a low-temperature CCD camera for application in computed tomography (CT) was tested on beamline II-3 at the Stanford Synchrotron Radiation Laboratory (SSRL). In the present system, transmitted x-rays are converted to visible light on a phosphor-coated optical face plate. This light illuminates a thermoelectrically cooled CCD, which is operated as a charge counting device. By modulating the energy of the x-ray beam, we can obtain elemental and chemical-state information about the reconstructed voxels. Presently, the resolution is about 50 microns, and is to a large extent controlled by the quality of the phosphor. The spatial resolution and chemical sensitivity of the system are reported. Applications to materials and biological sciences are discussed.
Date: August 1, 1986
Creator: Kinney, J.H.; Johnson, Q.C.; Brase, J.M.; Nichols, M.C.; Nusshardt, R. & Bonse, U.
Partner: UNT Libraries Government Documents Department

Phase-Based Road Detection in Multi-Source Images

Description: The problem of robust automatic road detection in remotely sensed images is complicated by the fact that the sensor, spatial resolution, acquisition conditions, road width, road orientation and road material composition can all vary. A novel technique for detecting road pixels in multi-source remotely sensed images based on the phase (i.e., orientation or directional) information in edge pixels is described. A very dense map of edges extracted from the image is separated into channels, each containing edge pixels whose phases lie within a different range of orientations. The edge map associated with each channel is de-cluttered. A map of road pixels is formed by re-combining the de-cluttered channels into a composite edge image which is itself then separately de-cluttered. Road detection results are provided for DigitalGlobe and TerraServerUSA images. Road representations suitable for various applications are then discussed.
Date: June 16, 2004
Creator: Sengupta, S K; Lopez, A S; Brase, J M & Paglieroni, D W
Partner: UNT Libraries Government Documents Department

Fast Wavefront Reconstruction in Large Adaptive Optics Systems Using the Fourier Transform

Description: Wavefront Reconstruction using the Fast Fourier Transform and spatial filtering is shown to be computationally tractable and sufficiently accurate for use in large Shack Hartmann-based adaptive optics systems (up to at least 10,000 actuators). This method is significantly faster and can have lower noise propagation than traditional VMM reconstructors. The boundary problem which prevented the accurate reconstruction of phase in circular apertures using square-grid FTs is identified and solved. The methods are adapted for use on the Fried-geometry. Detailed performance analysis of mean squared error and noise propagation for FT methods is presented, using both theory and simulation.
Date: January 13, 2002
Creator: Poyneer, L; Gravel, D T & Brase, J M
Partner: UNT Libraries Government Documents Department

Fast Fourier and Wavelet Transforms for Wavefront Reconstruction in Adaptive Optics

Description: Wavefront reconstruction techniques using the least-squares estimators are computationally quite expensive. We compare wavelet and Fourier transforms techniques in addressing the computation issues of wavefront reconstruction in adaptive optics. It is shown that because the Fourier approach is not simply a numerical approximation technique unlike the wavelet method, the Fourier approach might have advantages in terms of numerical accuracy. However, strictly from a numerical computations viewpoint, the wavelet approximation method might have advantage in terms of speed. To optimize the wavelet method, a statistical study might be necessary to use the best basis functions or ''approximation tree.''
Date: July 28, 2000
Creator: Dowla, F U; Brase, J M & Olivier, S S
Partner: UNT Libraries Government Documents Department

Adaptive optics at Lick Observatory: System architecture and operations

Description: We will describe an adaptive optics system developed for the 1 meter Nickel and 3 meter Shane telescopes at Lick Observatory. Observing wavelengths will be in the visible for the 1 meter telescope and in the near IR on the 3 meter. The adaptive optics system design is based on a 69 actuator continuous surface deformable mirror and a Hartmann wavefront sensor equipped with an intensified CCD framing camera. The system has been tested at the Cassegrain focus of the 1 meter telescope where the subaperture size is 12.5 cm. The wavefront control calculations are performed on a four processor single board computer controlled by a Unix-based system. We will describe the optical system and give details of the wavefront control system design. We will present predictions of the system performance and initial test results.
Date: March 1, 1994
Creator: Brase, J. M.; An, J. & Avicola, K.
Partner: UNT Libraries Government Documents Department

An adaptive optics package designed for astronomical use with a laser guide star tuned to an absorption line of atomic sodium

Description: We present the design and implementation of a very compact adaptive optic system that senses the return light from a sodium guide-star and controls a deformable mirror and a pointing mirror to compensate atmospheric perturbations in the wavefront. The deformable mirror has 19 electrostrictive actuators and triangular subapertures. The wavefront sensor is a Hartmann sensor with lenslets on triangular centers. The high-bandwidth steering mirror assembly incorporates an analog controller that samples the tilt with an avalanche photodiode quad cell. An {line_integral}/25 imaging leg focuses the light into a science camera that can either obtain long-exposure images or speckle data. In laboratory tests overall Strehl ratios were improved by a factor of 3 when a mylar sheet was used as an aberrator. The crossover frequency at unity gain is 30 Hz.
Date: April 11, 1994
Creator: Salmon, J. T.; Avicola, K. & Brase, J. M.
Partner: UNT Libraries Government Documents Department

Tip-tilt compensation: Resolution limits for ground-based telescopes using laser guide star adaptive optics. Revision 2

Description: The angular resolution of long-exposure images from ground-based telescopes equipped with laser guide star adaptive optics systems is fundamentally limited by the the accuracy with which the tip-tilt aberrations introduced by the atmosphere can be corrected. Assuming that a natural star is used as the tilt reference, the residual error due to tilt anisoplanatism can significantly degrade the long-exposure resolution even if the tilt reference star is separated from the object being imaged by a small angle. Given the observed distribution of stars in the sky, the need to find a tilt reference star quite close to the object restricts the fraction of the sky over which long-exposure images with diffraction limited resolution can be obtained. In this paper, the authors present a comprehensive performance analysis of tip-tilt compensation systems that use a natural star as a tilt reference, taking into account properties of the atmosphere and of the Galactic stellar populations, and optimizing over the system operating parameters to determine the fundamental limits to the long-exposure resolution. Their results show that for a ten meter telescope on Mauna Kea, if the image of the tilt reference star is uncorrected, about half the sky can be imaged in the V band with long-exposure resolution less than 60 milli-arc-seconds (mas), while if the image of the tilt reference star is fully corrected, about half the sky can be imaged in the V band with long-exposure resolution less than 16 mas. Furthermore, V band images long-exposure resolution of less than 16 mas may be obtained with a ten meter telescope on Mauna Kea for unresolved objects brighter than magnitude 22 that are fully corrected by a laser guide star adaptive optics system. This level of resolution represents about 70% of the diffraction limit of a ten meter telescope in the V band ...
Date: October 8, 1992
Creator: Olivier, S. S.; Max, C. E.; Gavel, D. T. & Brase, J. M.
Partner: UNT Libraries Government Documents Department

Intracavity, adaptive correction of a high-average-power, solid-state, heat-capacity laser

Description: The Solid-State, Heat-Capacity Laser (SSHCL) program at Lawrence Livermore National Laboratory is a multigeneration laser development effort scalable to the megawatt power levels. Wavefront quality is a driving metric of its performance. A deformable mirror with over 100 degrees of freedom situated within the cavity is used to correct both the static and dynamic aberrations sensed with a Shack-Hartmann wavefront sensor. The laser geometry is an unstable, confocal resonator with a clear aperture of 10 cm x 10 cm. It operates in a pulsed mode at a high repetition rate (up to 200 Hz) with a correction being applied before each pulse. Wavefront information is gathered in real-time from a low-power pick-off of the high-power beam. It is combined with historical trends of aberration growth to calculate a correction that is both feedback and feed-forward driven. The overall system design, measurement techniques and correction algorithms are discussed. Experimental results are presented.
Date: January 5, 2005
Creator: LaFortune, K N; Hurd, R L; Brase, J M & Yamamoto, R M
Partner: UNT Libraries Government Documents Department

Computer-Aided Content-Based Cueing of Remotely Sensed Images with the Image Content Engine (ICE)

Description: Human analysts are often unable to meet time constraints on analysis and interpretation of large volumes of remotely sensed imagery. To address this problem, the Image Content Engine (ICE) system currently under development is organized into an off-line component for automated extraction of image features followed by user-interactive components for content detection and content-based query processing. The extracted features are vectors that represent attributes of three entities, namely image tiles, image regions and shapes, or suspected matches to models of objects. ICE allows users to interactively specify decision thresholds so that content (consisting of entities whose features satisfy decision criteria) can be detected. ICE presents detected content to users as a prioritized series of thumbnail images. Users can either accept the detection results or specify a new set of decision thresholds. Once accepted, ICE stores the detected content in database tables and semantic graphs. Users can interactively query the tables and graphs for locations at which prescribed relationships between detected content exist. New queries can be submitted repeatedly until a satisfactory series of prioritized thumbnail image cues is produced. Examples are provided to demonstrate how ICE can be used to assist users in quickly finding prescribed collections of entities (both natural and man-made) in a set of large USGS aerial photos retrieved from TerraserverUSA.
Date: June 22, 2004
Creator: Weinert, G F; Brase, J M & Paglieroni, D W
Partner: UNT Libraries Government Documents Department

Intracavity adaptive correction of a 10 kW, solid-state, heat-capacity laser

Description: The Solid-State, Heat-Capacity Laser (SSHCL), under development at Lawrence Livermore National Laboratory (LLNL) is a large aperture (100 cm{sup 2}), confocal, unstable resonator requiring near-diffraction-limited beam quality. There are two primary sources of the aberrations in the system: residual, static aberrations from the fabrication of the optical components and predictable, time-dependent, thermally-induced index gradients within the gain medium. A deformable mirror placed within the cavity is used to correct the aberrations that are sensed externally with a Shack-Hartmann wavefront sensor. Although the complexity of intracavity adaptive correction is greater than that of external correction, it enables control of the mode growth within the resonator, resulting in the ability to correct a more aberrated system longer. The overall system design, measurement techniques and correction algorithms are discussed. Experimental results from initial correction of the static aberrations and dynamic correction of the time-dependent aberrations are presented.
Date: May 13, 2004
Creator: LaFortune, K N; Hurd, R L; Brase, J M & Yamamoto, R M
Partner: UNT Libraries Government Documents Department

Phase retrieval for adaptive optics system calibration

Description: Our objective in this report is to develop methods to determine the output pupil wavefront using intensity measurements directly from the science detector. This wavefront can then be used to determine a reference wavefront which will precorrect for the non-common-path aberrations and produce the desired wavefront at the science detector. We describe two phase retrieval algorithms that can be used and a set of simulation studies of AO system calibration. We present the initial experimental results of applying this technique in calibration of the Lick Observatory laser guidestar AO system in a later paper.
Date: August 1, 1997
Creator: Brase, J.M.; Carrano, C.J.; Macintosh, B.A.; Olivier, S.S. & An, J.R.
Partner: UNT Libraries Government Documents Department

Progress reports for period November 1--30, 1994 -- Joint UK/US Radar Program

Description: This report gives the principle investigator, objectives, recent accomplishments, milestones for reporting period, expected milestones for ensuing period, other issues and planned expenditures for the following programs: airborne RAR/SAR; radar data processor; ground-based SAR signal processing workstation; static airborne radar; multi-aperture space-time array radar; radar field experiments; data analysis and detection theory; management; E-2C radar data analysis;modeling and analysis; current meter array; UCSB wave tank; stratified flow facility; and IR sensor system. Budget status is also given.
Date: December 19, 1994
Creator: Twogood, R.E.; Brase, J.M.; Mantrom, D.D.; Chambers, D.H. & Robey, H.F.
Partner: UNT Libraries Government Documents Department

Progress reports for October 1994 -- Joint UK/US Radar Program

Description: This report gives the principle investigator, objectives, recent accomplishments, milestones for reporting period, expected milestones for ensuing period, other issues and planned expenditures for each of the following programs: airborne RAR/SAR; radar data processor; ground-based SAR signal processing workstation; static airborne radar; multi-aperture space-time array radar; radar field experiments; data analysis and detection theory; management; E-2C radar data analysis; modeling and analysis; current meter array; UCSB wave tank; stratified flow facility; and IR sensor system. Finally the budget status is given.
Date: November 18, 1994
Creator: Twogood, R.E.; Brase, J.M.; Mantrom, D.D.; Chambers, D.H. & Robey, H.F.
Partner: UNT Libraries Government Documents Department