摘要:

AbstractImaging techniques are presented for developing interactive computer display of cable network structures on a microcomputer such as the IBM PS/2®. These structures create surfaces formed by an orthogonal mesh of cables and are primarily loaded normal to the surface. A three‐dimensional perspective representation of network structures is developed for fast drawing of cable structures on microcompute

ISSN:0899-9457    

DOI:10.1002/ima.1850020302

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper describes a new algorithm which uses Gaussian and mean curvature values of the terrain surface to extract feature points. These points are then used for recognition of particular subregions of the terrain and in estimating relative positions of these subregions in the terrain. The Gaussian and mean curvatures are chosen because they are invariant under rotation and translation. In the Gaussian and mean curvature images, the points of maximum and minimum curvatures are extracted and used for matching. The stability of the position of these points in the presence of noise and with resampling is investigated. The input for this algorithm is 3D digital terrain data. Curvature values are calculated from the data by fitting a quadratic surface over a square window and calculating directional derivatives of this surface. A method of surface fitting that is invariant to sensor‐centered coordinate system transformation is suggested and implemented. Real terrain data are used in our experiments. The algorithm is tested with and without the presence of noise, and its performance is describe

ISSN:0899-9457    

DOI:10.1002/ima.1850020303

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe Khoros system integrates multiple user interface modes, code generators, instructional aids, data visualization, and information processing to produce a comprehensive image processing research tool. This system can easily be tailored to other application domains because the tools of the system can modify themselves as well as the system. This attribute is important in a system that is designed to be extensible and portable. The Khoros infrastructure consists of three major components: a high‐level user interface specification, methods of software development embedded in a code generation tool set, and an interoperable data exchange format and algorithm library. These basic facilities have been used to build a set of applications for performing image processing research, algorithm development, and data visualization. One of the most powerful features of the system is its high‐level abstract visual language. Khoros is a successful demonstration of how development programming, end‐user applications programming, information processing, data display, instruction, documentation, and maintenance can be integrated to build a state‐of‐the‐art image/data processing and visualization software

ISSN:0899-9457    

DOI:10.1002/ima.1850020304

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractIn this article we report the recent results of tomographic image reconstructions of multiple‐layer specimens at 100 MHz with the Scanning Tomographic Acoustic Microscope (STAM) system. The experiment utilizes 12 uniformly spaced projections and the results show significant improvement over the holographic image

ISSN:0899-9457    

DOI:10.1002/ima.1850020305

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe show theoretically and experimentally that beam profiling with a vibrating knife exhibits spatial resolution equal to the knife‐edge excursion. We discuss the implications of this for near‐field optical scanning microscopy, propose an extension of the method to two dimensions, and calculate impulse response, step response, and spatial frequency respo

ISSN:0899-9457    

DOI:10.1002/ima.1850020306

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractTraditionally, knowledge of the ionospheric electron density is obtained using Faraday rotation or differential Doppler techniques which measure total electron content in columns of the ionosphere. Conventional data processing can only image the electron density in the direction perpendicular to these columns, thereby forming one‐dimensional images. Because this data is proportional to line integrals through the region of interest, tomographic techniques may be used to reconstruct two‐dimensional electron density images. In this paper, the resolution limit of the image reconstruction process is analyzed in terms of limited‐angle tomog

ISSN:0899-9457    

DOI:10.1002/ima.1850020307

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractMicrowave images for objects in motion can be obtained with quality as good as those obtained in the stationary case if the signal waveforms, data acquisition systems, and image reconstruction algorithms are cleverly designed. The principle of imaging for objects in motion is to eliminate the gross Doppler effect of the echo signals and only reserve the differential Doppler information to reconstruct the image. Accordingly, requirements for parameters of the signal waveform are established. Two steps are involved in the image reconstruction algorithm: range alignment and phase compensation. Focused images of complex‐shaped targets with simulated motion have been obtained experimentall

ISSN:0899-9457    

DOI:10.1002/ima.1850020308

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractElastic waves, produced by temporally and spatially finite fault ruptures during earthquakes, propagate through the Earth. Recordings of these waves at the Earth's surface provide the data for reconstruction of the source properties, including location, spatial and temporal extents, and rupture velocities. A 2D finite‐difference solution of the elastic wave equation is used to numerically extrapolate synthetic observations backward in time to create images of the energy release during an earthquak

ISSN:0899-9457    

DOI:10.1002/ima.1850020309

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThere are some compelling reasons for viewing the problem of image reconstruction from noisy or incomplete data as one of statistical estimation, i.e., of choosing, from the infinity of images consistent with the data, that image which, in some statistical sense, is most plausible. Among these reasons are the soundness of the philosophical underpinning of the resulting image reconstruction process, a greater realization of the image resolution which is inherent in the data, and freedom from many of the artifacts encountered in commonly usedad hocreconstruction schemes. One successful technique employing a principle of statistical inference is the maximum entropy technique, in which the data‐consistent image with maximum configurational entropy is chosen. It is a computationally intensive approach involving a conjugate gradient search over a convex function of a vector in a space of dimensionality equal to the number of image pixels. This technique has been employed with success in situations where the data samples are modeled as linearly related to a real non‐negative object. We investigate application of maximum entropy image reconstruction to the problem of high‐resolution radar diagnostic imaging. The problem differs from others in which maximum entropy has been applied in that the object to be imaged is complex. Although the desired image is of the magnitude of the complex object and is thus real and non‐negative, there is no linear relationship beween object magnitude and data. Rather, the data are linearly related to the complex object. Several earlier proposed methods for applying the maximum entropy principle to this problem are identified and analyzed. A method that more closely approximates true Bayesian estimation is p

ISSN:0899-9457    

DOI:10.1002/ima.1850020310

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY

ISSN:0899-9457    

DOI:10.1002/ima.1850020301

出版商:John Wiley&Sons, Inc.    

年代:1990

数据来源: WILEY