Three-dimensional pattern recognition with a single two-dimensional synthetic reference function

A novel, to our knowledge, method of distortion-invariant three-dimensional (3-D) pattern recognition is proposed. A single two-dimensional synthetic discriminant function is employed as a reference function in the 3-D correlator. Thus the proposed system is able to identify and locate any true-class object in the 3-D scene. Preliminary simulation and experimental results are presented.     

Two-dimensional shifting tolerance of a volume-holographic correlator

A simple method for simulating two-dimensional (2-D) distributions of the diffraction lights of a volume-holographic-type VanderLugt correlator is proposed and demonstrated. The simulation results are similar to those of the corresponding experiments, and only a few dozen points are sampled from both the input and the reading patterns. We show that the shifting tolerance to the reading pattern is a result of Bragg degeneracy and is not isotropic. The Bragg degeneracy generates different degrees of cross talk between the horizontal and the vertical directions. With the method we further simulate the 2-D shifting tolerance of the volume-holographic correlator. The simulation results offer a clear picture of the diffraction in a transmission volume hologram used as an optical spatial correlator.     

Three-dimensional joint transform correlator

The three-dimensional (3-D) joint transform correlator is demonstrated with realistic targets. Three-dimensional objects observed by multiple cameras are correlated with a 3-D reference object. The number of cameras and their directions of observation are particularly considered.     

Aperture tapering in a coherent optical correlator

Sharp edges located in an optical correlator input beam cause unwanted edge effects. A 1-D analysis is used to demonstrate this effect and how edge tapers can reduce this effect. Then an aperture made on film approximating the best taper is used to reduce the spurious signals in a matched filter correlator.     

Three-dimensional object recognition by fourier transform profilometry

An automatic method for three-dimensional (3-D) shape recognition is proposed. It combines the Fourier transform profilometry technique with a real-time recognition setup such as the joint transform correlator (JTC). A grating is projected onto the object surface resulting in a distorted grating pattern. Since this pattern carries information about the depth and the shape of the object, their comparison provides a method for recognizing 3-D objects in real time. A two-cycle JTC is used for this purpose. Experimental results demonstrate the theory and show the utility of the new proposed method.     

A comparison of two correlation schemes

Processes involving the cross-correlation of two noisy data streams are frequently encountered in signal processing. The performances of two commonly used correlators, the simple and complex correlators, are examined. The conventional view is that the complex correlator is superior to the simple correlator by a factor of the square root of two in output signal-to-noise ratio (SNR). However, by modifying the simple correlator to utilize all the available information, its performance is improved. The development of the modified correlator is explained, and a computer simulation shows that this modified correlator is approximately equivalent to the complex correlator in noise performance     

Rotation-invariant optical recognition of three-dimensional objects

An automatic method for rotation-invariant three-dimensional (3-D) object recognition is proposed. The method is based on the use of 3-D information contained in the deformed fringe pattern obtained when a grating is projected onto an object's surface. The proposed method was optically implemented by means of a two-cycle joint transform correlator. The rotation invariance is achieved by means of encoding with the fringe pattern a single component of the circular-harmonic expansion derived from the target. Thus the method is invariant for rotations around the line of sight. The whole experimental setup can be constructed with simple equipment. Experimental results show the utility of the proposed method.     

Two-dimensional wavelet processor

An optical implementation of the two-dimensional (2-D) wavelet transform and inverse wavelet transform is performed in real time by the exploitation of a new multichannel system that processes the different daughter wavelets separately. The so-coined wavelet-processor system relies on a multichannel replication array generated that uses a Dammann grating and is able to handle every wavelet function. All channels process in parallel using a conventional 2-D correlator. Experimental results applying the Mexican-hat wavelet-decomposition technique are presented.     

A new time-domain narrowband velocity estimation technique for Doppler ultrasound flow imaging. II. Comparative performance assessment

For pt.I see ibid., vol.45, no.4, pp.939-54 (1998). The statistical performance of the new 2-D narrowband time-domain root-MUSIC blood velocity estimator described previously is evaluated using both simulated and flow phantom wideband (50% fractional bandwidth) ultrasonic data. Comparisons are made with the standard 1-D Kasai estimator and two other wideband strategies: the time domain correlator and the wideband point maximum likelihood estimator. A special case of the root-MUSIC, the "spatial" Kasai, is also considered. Simulation and flow phantom results indicate that the root-MUSIC blood velocity estimator displays a superior ability to reconstruct spatial blood velocity information under a wide range of operating conditions. The root-MUSIC mode velocity estimator can be extended to effectively remove the clutter component from the sample volume data. A bimodal velocity estimator is formed by processing the signal subspace spanned by the eigenvectors corresponding to the two largest eigenvalues of the Doppler correlation matrix. To test this scheme, in vivo common carotid flow complex Doppler data was obtained from a commercially available color flow imaging system. Velocity estimates were made using a reduced form of this data corresponding to higher frame rates. The extended root-MUSIC approach was found to produce superior results when compared to both 1- and 2-D Kasai-type estimators that used initialized clutter filters. The results obtained using simulated, flow phantom, and in vivo data suggest that increased sensitivity as well as effective clutter suppression can be achieved using the root-MUSIC technique, and this may be particularly important for wideband high frame rate imaging applications.     

Object recognition using three-dimensional optical quasi-correlation

A novel method of three-dimensional (3-D) object recognition is proposed. Several projections of a 3-D target are recorded under white-light illumination and fused into a single complex two-dimensional function. After proper filtering, the resulting function is coded into a computer-generated hologram. When this hologram is coherently illuminated, a correlation space is reconstructed such that light peaks indicate the existence and locations of true targets in the observed 3-D scene. Experimental results and comparisons with results of another 3-D object recognition technique are presented.     

Incoherent-only joint-transform correlator

An incoherent-only optical and electronic digital joint-transform correlator is proposed. A technique for the removal of extraneous signals inherent in the incoherent-only joint-transform correlator is also presented. A computer simulation and experimental results confirm the performance of the proposed incoherent-only joint-transform correlator.     

Fractional profilometry correlator for three-dimensional object recognition

A novel method for three-dimensional shape recognition is proposed. It combines the Fourier-transform-profilometry technique with a two-dimensional fractional correlation algorithm. A grating is projected onto the object surface, resulting in a distorted grating pattern that carries information about the height and the shape of the object. Three-dimensional objects are recognized by a fractional correlator by use of the transformed complex amplitude. An optoelectronic hybrid implementation is also suggested.     

An integral-equation/singularity-method approach for 3-D electromagnetic field determination in the end region of a turbine-generator

A mathematical model using an integral-equation/singularity-method approach is derived for determining the magnetic field and electromagnetic forces induced by current-carrying conductors in a region bounded by 3-D material-body surfaces which have complex configurations. Special analytical and numerical techniques that eliminate near-field computational difficulties and bypass the cumbersome matrix manipulations required by other integral-equation approaches are described. A comprehensive computer program package has been developed using this approach for obtaining the 3-D solutions in the end region of a turbine-generator due to armature end windings. Special computational techniques for handling the complex end-winding and surface geometry are described and detailed numerical results are presented for the 3-D field solution and the forces acting on the conductors.     

Distortion-invariant fringe-adjusted joint transform correlation

A distortion-invariant joint transform correlator based on the concepts of the fringe-adjusted joint transform correlator and the synthetic discriminant function is presented. Computer-simulation results show that the proposed joint transform correlator is distortion-invariant for the target image from the training set and produces sharper correlation peaks and lower sidelobes compared with the classical joint transform correlator.     

3D finite element solution of complex magnetostatic probleminvolving axial and radial excitation-using a single scalar potential

The fictitious magnetic monopole model (FMMM) of motors having a complex magnetostatic field excited by both axial (permanent) and radial current is established. A single scalar potential is used to derive a precise solution of the 3-D anisotropic nonlinear rotational field in such a motor. The 3-D FEM (finite-element method) solution is used to modify the conventional `2-D field-circuit' calculation model     

Large-capacity real-time spatial-spectral scanning optical correlator

A large-capacity real-time spatial-spectral scanning optical correlator utilizing the concept of a rotating multicolor grating is described. It was experimentally observed that implementation of a closed-circuit TV system gives the correlator a real-world application. The color sensitivity of the correlator is also demonstrated. The experimental results using single and double lasers with two primary colors are presented.     

Experimental systems implementation of a hybrid optical-digital correlator

A high-speed hybrid optical-digital correlator system was designed, constructed, modeled, and demonstrated experimentally. This correlator is capable of operation at approximately 3000 correlations/s. The input scene is digitized at a resolution of 512 x 512 pixels and the phase information of the two-dimensional fast Fourier transform calculated and displayed in the correlator filter plane at normal video frame rates. High-fidelity reference template images are stored in a phase-conjugating optical memory placed at the nominal input plane of the correlator and reconstructed with a high-speed acousto-optic scanner; this allows for cross correlation of the entire reference data set with the input scene within one frame period. A high-speed CCD camera is used to capture the correlation-plane image, and rapid correlation-plane processing is achieved with a parallel processing architecture.     

Enumeration algorithm for determination of binding constants in capillary electrophoresis

With more accurate simulation models and more efficient algorithms becoming available, the binding constants of an affinity interaction can be obtained from much simpler experiments using capillary electrophoresis. With the enumeration algorithm, all possible combinations of the binding constant and the complex mobility in certain ranges that could result in the experimental migration time of an injected analyte are extracted from a 3-D surface, which depicts the migration times resulting from different values of the binding constant and the mobility of the complex formed between the interacting pair, to form a 2-D curve. When the experimental conditions are changed, the analyte migration time will also change. A new 2-D curve can be constructed from another 3-D surface on the basis of the pairs of binding constants and complex mobility values that could result in the new migration time. Because the true binding constant and complex mobility values have to be the same for both experimental conditions under the same temperature, there has to be a point where both 2-D curves will converge. The coordinates of the converging point give the values for a binding constant and a complex mobility that will fit all 2-D curves generated under certain experimental conditions. p-Nitrophenol is used as the analyte, beta-cyclodextrin is used as the additive, and a one-cell model is used to simulate affinity CE. The experimental conditions that can improve the accuracy of the binding constants are discussed.     

Compact phase-conjugating correlator: simulation and experimental analysis

A simulation and experimental investigation of a recently proposed, compact, phase-conjugating correlator is undertaken. The effects of noise and other distortions in the input image and in the correlator filter plane are considered. As with other phase-only designs, the phase-conjugating correlator is sensitive to distortion of the input image while being robust in the presence of filter-plane distortions; this robustness is enhanced by the phase-conjugating property of the design.     

Modified morphological correlation based on bit-map representations

Pattern recognition with high discrimination can be achieved with a morphological correlator. A modification of this correlator is carried out by use of a binary slicing process instead of linear thresholding. Although the obtained correlation result is not identical to the conventional morphological correlation, it requires fewer calculations and provides even higher discrimination. Two optical experimental implementations of this modified morphological correlator as well as some experimental results are shown.