Ray phase space approach for 3-D imaging and 3-D optical data representation

We propose a framework to model, analyze and design three-dimensional (3-D) imaging systems. A system engineering approach is adopted which relates 3-D images (real or synthesized) to 3-D objects (real or synthesized) using a novel representation of the optical data which we call "ray phase space". The framework provides a powerful tool for determining the performance of 3-D imaging systems, for generating computational reconstruction of 3-D images and for optimizing 3-D imaging systems.     

Concurrent 3-D motion segmentation and 3-D interpretation of temporal sequences of monocular images.

The purpose of this study is to investigate a variational method for joint multiregion three-dimensional (3-D) motion segmentation and 3-D interpretation of temporal sequences of monocular images. Interpretation consists of dense recovery of 3-D structure and motion from the image sequence spatiotemporal variations due to short-range image motion. The method is direct insomuch as it does not require prior computation of image motion. It allows movement of both viewing system and multiple independently moving objects. The problem is formulated following a variational statement with a functional containing three terms. One term measures the conformity of the interpretation within each region of 3-D motion segmentation to the image sequence spatiotemporal variations. The second term is of regularization of depth. The assumption that environmental objects are rigid accounts automatically for the regularity of 3-D motion within each region of segmentation. The third and last term is for the regularity of segmentation boundaries. Minimization of the functional follows the corresponding Euler-Lagrange equations. This results in iterated concurrent computation of 3-D motion segmentation by curve evolution, depth by gradient descent, and 3-D motion by least squares within each region of segmentation. Curve evolution is implemented via level sets for topology independence and numerical stability. This algorithm and its implementation are verified on synthetic and real image sequences. Viewers presented with anaglyphs of stereoscopic images constructed from the algorithm's output reported a strong perception of depth.     

Exact and approximate rebinning algorithms for 3-D PET data

This paper presents two new rebinning algorithms for the reconstruction of three-dimensional (3-D) positron emission tomography (PET) data. A rebinning algorithm is one that first sorts the 3-D data into an ordinary two-dimensional (2-D) data set containing one sinogram for each transaxial slice to be reconstructed; the 3-D image is then recovered by applying to each slice a 2-D reconstruction method such as filtered-backprojection. This approach allows a significant speedup of 3-D reconstruction, which is particularly useful for applications involving dynamic acquisitions or whole-body imaging. The first new algorithm is obtained by discretizing an exact analytical inversion formula. The second algorithm, called the Fourier rebinning algorithm (FORE), is approximate but allows an efficient implementation based on taking 2-D Fourier transforms of the data. This second algorithm was implemented and applied to data acquired with the new generation of PET systems and also to simulated data for a scanner with an 18° axial aperture. The reconstructed images were compared to those obtained with the 3-D reprojection algorithm (3DRP) which is the standard “exact” 3-D filtered-backprojection method. Results demonstrate that FORE provides a reliable alternative to 3DRP, while at the same time achieving an order of magnitude reduction in processing time     

三维测量数据同步自动配准方法

提出一种三维(3-D)视觉测量数据同步自动配准方法。利用改进的3-Dshape context描述符建立当前测量数据与已获得数据间的匹配点对,得到候选的重叠数据,并用最近点迭代(ICP)算法进行验证和精确配准。将视觉传感器每次获得的测量数据与已获得的测量数据配准,最终将所有测量数据统一到同一坐标系下。实验时,采用视觉传感器对维纳斯石膏像进行多角度测量,对测量数据进行同步配准,获得石膏像表面完整的3-D模型。该配准方法无需任何外部辅助设备,便于操作者观察测量进度并及时调整视觉传感器路径规划,从而提高三维形貌测量效率。     

科学级CCD三维噪声模型及其评估

为了评估科学CCD噪声带给激光近场分布测量的影响,采用三维噪声模型,分析了科学级CCD的噪声,并将CCD的噪声分解为空间噪声和时间噪声。空间噪声用来评估CCD像元之间响应不一致性对测量的影响,时间噪声用来评估多次测量不一致性对测量的影响。通过设计测量系统对CCD三维噪声进行测量,并分析时空噪声的统计分布规律,发现两者均是依赖于信号、近似服从正态分布,建立了依赖于信号的时空噪声的数学模型,并实验验证了该模型是有效的。     

Dominant pattern extraction from 3-D kinematic data

A new method for the extraction of a repeating pattern in cyclic biomechanical data is proposed-singular value decomposition pattern analysis (SVDPA). This method is based on the recent work of Kanjilal and Palit (1994, 1995) and can be applied to both contiguous and repeated trials without being constrained to be strictly periodic. SVDPA is a data-driven approach that does not use a preselected set of basis functions; but instead utilizes a data matrix with a special structure to identify repeating patterns. Several important features of SVDPA are described including its close relationship to the Kahunen-Loeve transform. The dominant pattern is defined as the average energy component (AEC). The AEC is obtained from the SVD of the data matrix and is equivalent to the optimal [maximal signal-to-noise ratio (SNR)] ensemble average pattern. The degree of periodicity and SNR for the AEC are defined explicitly from the singular values of the data matrix. The authors illustrate the usefulness of SVDPA for dominant pattern extraction by applying it to the quasiperiodic three-dimensional trajectory of a marker attached to the trunk during treadmill locomotion. The AEC obtained for the normalized trajectory and error estimates at each point suggests that SVDPA could be a useful tool for the extraction of the fine details from cyclic biomechanical data     

Symmetry-constrained 3-D interpolation of viral X-raycrystallography data

A three-dimensional (3-D) interpolation problem that is important in viral X-ray crystallography is considered. The problem requires new methods because the function is known to have icosahedral symmetry, the data is corrupted by experimental errors and therefore lacks the symmetry, the problem is 3-D, the measurements are irregularly spaced, and the number of measurements is large (10⁴). A least-squares approach is taken using two sets of basis functions: the functions implied by a minimum-energy bandlimited exact interpolation problem and a complete orthonormal set of bandlimited functions. A numerical example of the Cowpea Mosaic Virus is described     

Evaluation of antenna diversity performance for mobile handsetsusing 3-D measurement data

An evaluation of two-branch antenna diversity on mobile telephones is performed in the presence of head and hand phantoms to model the influence of the user. Two mobile telephone prototypes for the 1800-MHz band are considered. The evaluation is done by measuring the three-dimensional (3-D) complex radiation patterns from each antenna with the prototypes positioned near the phantom head and hand (i.e., in talk position) and calculating the diversity performance for three different scenarios of the incoming field. The two-branch antenna setups on both prototypes produce a calculated diversity gain of about 9 dB for selection diversity at the 99% reliability level     

3-D pain drawings-mobile data collection using a PDA

A large number of the adult population suffers from some kind of back pain during their lifetime. Part of the process of diagnosing and treating such back pain is for a clinician to collect information as to the type and location of the pain that is being suffered. Traditional approaches to gathering and visualizing this pain data have relied on simple 2-D representations of the human body, where different types of sensation are recorded with various monochrome symbols. Although patients have been shown to prefer such drawings to traditional questionnaires, these pain drawings can be limited in their ability to accurately record pain. The work described in this paper proposes an alternative that uses a 3-D representation of the human body, which can be marked in color to visualize and record the pain data. This study has shown that the new approach is a promising development in this area of medical practice and has been positively received by patients and clinicians alike.     

真三维活动视频数据的优化研究

提出了一种基于点阵的真三维视频显示技术,该系统利用LED为单元节点组成三维空间阵列,用于显示真三维活动影像。由于数据量巨大,为了加快处理速度,利用CUDA编程模型对计算过程进行优化,把处理过程中可以并行计算的部分交由GPU执行。先把要处理的视频数据传到内存中,由CPU进行一些预处理,然后传到显存,由GPU对视频运动过程等进行处理,处理完后再传到内存,由CPU进行一些后续处理,最终把处理后的数据传出加以显示或存储。通过比较仅由CPU处理与用GPU优化后的计算时间,发现优化后计算速度比优化前快了几十到几百倍,而且数据量越大,优化效果越好,核心多的GPU所得到的加速比大,最后在实验部分给出了用OpenGL仿真的结果。     

Vision processing for realtime 3-D data acquisition based on coded structured light

Structured light vision systems have been successfully used for accurate measurement of 3-D surfaces in computer vision. However, their applications are mainly limited to scanning stationary objects so far since tens of images have to be captured for recovering one 3-D scene. This paper presents an idea for real-time acquisition of 3-D surface data by a specially coded vision system. To achieve 3-D measurement for a dynamic scene, the data acquisition must be performed with only a single image. A principle of uniquely color-encoded pattern projection is proposed to design a color matrix for improving the reconstruction efficiency. The matrix is produced by a special code sequence and a number of state transitions. A color projector is controlled by a computer to generate the desired color patterns in the scene. The unique indexing of the light codes is crucial here for color projection since it is essential that each light grid be uniquely identified by incorporating local neighborhoods so that 3-D reconstruction can be performed with only local analysis of a single image. A scheme is presented to describe such a vision processing method for fast 3-D data acquisition. Practical experimental performance is provided to analyze the efficiency of the proposed methods.     

Lossy to lossless object-based coding of 3-D MRI data

We propose a fully three-dimensional (3-D) object-based coding system exploiting the diagnostic relevance of the different regions of the volumetric data for rate allocation. The data are first decorrelated via a 3-D discrete wavelet transform. The implementation via the lifting steps scheme allows to map integer-to-integer values, enabling lossless coding, and facilitates the definition of the object-based inverse transform. The coding process assigns disjoint segments of the bitstream to the different objects, which can be independently accessed and reconstructed at any up-to-lossless quality. Two fully 3-D coding strategies are considered: embedded zerotree coding (EZW-3D) and multidimensional layered zero coding (MLZC), both generalized for region of interest (ROI)-based processing. In order to avoid artifacts along region boundaries, some extra coefficients must be encoded for each object. This gives rise to an overheading of the bitstream with respect to the case where the volume is encoded as a whole. The amount of such extra information depends on both the filter length and the decomposition depth. The system is characterized on a set of head magnetic resonance images. Results show that MLZC and EZW-3D have competitive performances. In particular, the best MLZC mode outperforms the others state-of-the-art techniques on one of the datasets for which results are available in the literature.     

Precise matching of 3-D target models to multisensor data

This paper presents a three-dimensional (3-D) model-based ATR algorithm that operates simultaneously on imagery from three heterogeneous, approximately boresight aligned sensors. An iterative search matches models to range and optical imagery by repeatedly predicting detectable features, measuring support for these features in the imagery, and adjusting the transformations relating the target to the sensors in order to improve the match. The result is a locally optimal and globally consistent set of 3-D transformations that precisely relate the best matching target features to combined range, IR, and color images. Results show the multisensor algorithm recovers 3-D target pose more accurately than does a traditional single-sensor algorithm. Errors in registration between images are also corrected during matching. The intended application is imaging from semiautonomous military scout vehicles.     

DataFoundry: information management for scientific data

Data warehouses and data marts have been successfully applied to a multitude of commercial business applications. They have proven to be invaluable tools by integrating information from distributed, heterogeneous sources and summarizing this data for use throughout the enterprise. Although the need for information dissemination is as vital in science as in business, working warehouses in this community are scarce because traditional warehousing techniques do not transfer to scientific environments. There are two primary reasons for this difficulty. First, schema integration is more difficult for scientific databases than for business sources because of the complexity of the concepts and the associated relationships. Second, scientific data sources have highly dynamic data representations (schemata). When a data source participating in a warehouse changes its schema, both the mediator transferring data to the warehouse and the warehouse itself need to be updated to reflect these modifications. The cost of repeatedly performing these updates in a traditional warehouse, as is required in a dynamic environment, is prohibitive. The paper discusses these issues within the context of the DataFoundry project, an ongoing research effort at Lawrence Livermore National Laboratory. DataFoundry utilizes a unique integration strategy to identify corresponding instances while maintaining differences between data from different sources, and a novel architecture and an extensive meta-data infrastructure, which reduce the cost of maintaining a warehouse     

A 3-D reconstruction algorithm for interpolation and extrapolation of planar cross sectional data

A three dimensional (3-D) reconstruction algorithm utilizing both linear interpolation and linear extrapolation was developed for the study of human prostatic cancer. The algorithm was validated by comparing the volumes and shapes of original to reconstructed objects. Synthetic objects of known geometry and wax models with shapes characteristic of prostatic carcinomas were assessed with standard planimetry and by the digital interpolation-extrapolation method. Volume and multifocality measurements obtained by reconstructing excised prostate glands using histologic maps obtained from whole-mount sections were tested. The new algorithm provided greater accuracy in determining tumor volumes than conventional methods. This model provides a basis for mathematical analysis of prostate cancer lesions.     

3-D vector radix algorithm for the 3-D new Mersenne numbertransform

Three-dimensional convolutions and correlations are used for three-dimensional image-processing applications. Their calculation involves extensive computation, which makes the use of fast transforms very advantageous. As the number of arithmetic operations is very large, the accumulation of rounding or truncation errors arising in the use of the fast Fourier and Hartley transforms tends to increase. Number theoretic transforms are calculated modulo an integer and hence they are not subject to these errors. Previously, a one-dimensional transform called the new Mersenne number transform (NMNT) was introduced and applied successfully to the calculation of 1-D convolutions/correlations. Unlike other Mersenne number transforms, the NMNT can handle long data sequences and has fast algorithms. In the paper, the 1-D definitions are first extended to the 3-D case in detail for use in 3-D image processing applications. The concept and derivation of the 3-D vector radix algorithm is then introduced for the fast calculation of the 3-D NMNT. The proposed algorithm is found to offer substantial savings over the row-column approach in terms of arithmetic operations. Examples are given showing the validity of both transform and algorithm     

Advanced interpretation techniques for earth data information systems

Advanced interpretation techniques used in remote sensing are surveyed in the context of earth data information systems. Included are methods for extracting information from the spectral, temporal, and spatial domains. The many types of data contained in modern earth data information systems constitute a generalized scene context which current research seeks to exploit more fully. Initial efforts in this direction are described. Significant research problems in several related areas are discussed.     

Flat Projection for 3-D

The two challenges for three-dimensional (3-D) display are designing the optics for wide fields of view, and delivering pixels at the rates needed to support this. Getting such pixel rates at low cost is merely an extension of the key challenge for two-dimensional (2-D) displays,and the cost advantage of projection in this respect over alternatives increases considerably at the data rates needed for 3-D. Both 2-D and 3-D projection concepts are bulky, so the authors describe how to project images within a flat panel. Flat projection is not only inexpensive: it can generate virtual as well as real images, and allows the screen to take images and input from the viewer as well as vice versa. Real images are created by pointing a projector into a wedge-shaped light guide, and either the projector or the screen can be shuttered in order to time-multiplex a 3-D image on a large screen. Virtual images are created by pointing a projector into a slab embossed with a grating and can deliver the collimated illumination needed if a liquid crystal display is to time-multiplex a 3-D image with the high off-screen resolution provided by holograms.