Showing papers on "3D reconstruction published in 1990"

Three-dimensional x-ray microtomography for medical and biological applications.

Abstract: Three-dimensional (3D) X-ray microtomography is a technique for obtaining the 3D distribution of X-ray attenuation coefficients within small objects. To obtain microtomographic images apparatus has been developed which consists of a microfocal X-ray source, a computer-controlled stage for rotating the object, a 2D multi-wire gas proportional X-ray counter and a microcomputer to control image acquisition. Projection data were generated by rotating the object to discrete orientations around a single axis until of the order of 100 2D projection images of the object were collected. The projection images were transferred to a VAX 11/750 computer for subsequent 3D reconstruction using a convolution and back-projection algorithm in cone-beam geometry. The reconstructed data, comprising cubic voxels, may be displayed as sets of sequential transaxial, sagittal and coronal planes through the object. Alternatively, perspective displays of individual orthogonal sections may be formed with either intersecting planes or with these planes projected onto the surfaces of a box-like structure.

Implementation of three-dimensional image reconstruction for multi-ring positron tomographs.

Abstract: In view of the number of PET studies involving low count rate acquisitions, there has been increasing interest recently in the development of positron cameras capable of fully three-dimensional acquisition and reconstruction. This interest has given impetus to the study of algorithms for 3D reconstruction, including those algorithms suitable for application to multi-ring PET scanners. While ZD reconstruction methods can often be generalised to 3D, a numbw of implementation problems arise which are unique to the 31) approach. This paper examines some of the difficulties associated with the generalisation of the filtered backprojection algorithm to 3D, paying particular attention to the approxima- tions and variable transformations required for application to data from a multi-ring scanner.

Temporally integrated surface reconstruction

Abstract: A solution is presented to the problem of obtaining and improving an estimate of the 3-D structure of a scene from a sequence of images. The algorithm, which combines single-frame reconstruction techniques and multiple-frame Kalman filtering, is tested on a variety of real motion image sequences. >

Surface reconstruction using deformable models with interior and boundary constraints

Abstract: A technique is introduced for 3-D surface reconstruction and graphic animation using elastic, deformable models. The basic structure used is an imaginary elastic grid, which is made of membranous, thin-plate type material. This elastic grid is bent, twisted, compressed, and stretched into any desirable 3-D shape, or from one flexible state to another. The desired shape can be specified by the shape constraints derived automatically from images of a real 3-D object, or by an analytic surface function. Shape reconstruction is guided by a set of imaginary springs that enforce the consistency in the position, orientation, and/or curvature measurements of the elastic grid and the desired shape. The dynamics of a reconstruction process is regulated by the Hamilton principle or the principle of the least action. Implementation results using simple analytic shapes and images of real free-form objects are presented. The authors believe that their model is widely applicable in many surface reconstruction and graphic animation processes. >

Collaboration between computer graphics and computer vision

Abstract: The scope concerns both applications related to computer vision such as vision for the robots of the next century and computer graphics such as audio-visuals or simulators of physical phenomena. It is a large field of new applications where refined 3-D recognition and interpretation (not yet generally solved today) will be required. The problem that the author solves more precisely is to understand and recognize a 3-D scene observed by two cameras in a stereo position, using a given model of the scene. >

Using surface model to correct and fit disparity data in stereo vision

Abstract: A method of stereo vision adapted to 3D reconstruction of urban scenes is presented. A generic geometric model for objects in the scene is assumed. Uniform intensity regions in the images are hypothesized to correspond to single surfaces in the scene. The hypothesis is either verified or refuted by testing whether matches in each region fit the model or not. Disparity errors are detected using a disparity gradient limit before interpolation. The method is tested on real images, and results are given. >

3D Reconstruction of High Contrast Objects Using a Multi-scale Detection / Estimation Scheme

Abstract: Reconstructing a three-dimensional (3D) volume from a set of twodimensional X-ray projections raises theoretical, instrumental and computational difficulties. Focused on high contrast objects, solutions are proposed for the successive steps of a 3D reconstruction procedure, from the raw measurements on an image intensifier up to the reconstruction algorithm based on a multi-scale detection / estimation scheme.

A New Edge Point/ Region Cooperative Segmentation Deduced From A 3D Scene Reconstruction Application

Abstract: This paper describes both method and first results of an indoor / outdoor 3D reconstruction application. Images are supposed to come from man-made environments. The method is based on a new cooperative segmentation designed from a rough model of such scenes. This modelisation consists of classically representing scenes by a universe composed of polyhedra, that we call general model. This allows to deduce an operating model, constituted by all the typical 3D tokens of a polyhedron: edges, vertices, plane faces. Their projections are 2D primitives as edge segments, junctions of segments, regions. Then a graph groups these features together . The segmentation principle is based on a loop of two detectors of dual image properties (homogeneity and disparity): each of them is controlled by the results of the other.

3D Bone Reconstruction From Two X-ray Views

Abstract: In this paper problem of 3D bone reconstruction starting from 2D conventional x-ray projections has been addressed in the pursuit of two major goals. The first goal consists of the 3D reconstruction of a bone and the recovery of some anomalies. The last goal is the simulation of the behaviour of the bone under orthopedic operations. Our approach is based on back-lighting projections, polygon mesh and b-spline interpolation and has been implemented in the AutoCad software environment.

Integration of a GPS receiver and a stereo-vision system in a vehicle

Abstract: The US Federal Highway Administration and the Center for Mapping of The Ohio State University are developing a prototype mapping vehicle that integrates a stereo-vision system, a GPS receiver, and some other sensors, to automatically collect data of the environment of roads at highway speeds and store this information in a GIS. Thirty eight states and one Canadian province are sponsoring this effort together with NASA. In this paper we discuss the integration of the stereo-vision system with a GPS-receiver and an inertial system in a mobile workstation. The major task of the vision system is the acquisition and storage of digital image pairs once a second. The shutters of the camera are synchronized by the clock of the GPS receiver. The system will be calibrated by analytical methods using a testfield of control points. The offset between the GPS antenna and the vision system is determined by a rigorous bundle- and geodetic adjustment. Beside the storage of images the vision system is used for sequential triangulation of stereo pairs along the road, to bridge over areas without satellite signals. We also try to extract the edges of roads automatically and compute its width. As the construction of the prototype is presently ongoing, preliminary results and the configuration of the hardware are presehted.

[7] - Three-Dimensional Computer Reconstruction of Perforated Synapses

Abstract: Publisher Summary This chapter provides an overview of the three-dimensional (3D) computer reconstruction of perforated synapses (PSs) in the neocortex as synaptic type has been implicated in the dynamic changes of synaptic plasticity in the post-developmental central nervous system Particles that undergo structural modification are particularly suitable for 3D reconstruction because dynamic morphological changes can be clearly appreciated It is for this reason that, for the study of PSs in the neocortex, the application of 3D reconstruction procedures is preferred It is a naturally occurring process in which synaptic connections are remodeled and/or replaced in response to various environmental stimuli Computer-assisted, 3D reconstruction methods for highlighting qualitative age-related differences among groups of synapses have considerable potential Some of their morphological features, such as profile area, terminal volume, and post-synaptic density (PSD) complexity, can be quantified for statistical analyses; reconstructions can be manipulated readily by altering various transformation options to produce the best reconstruction of the original synapse and can be stored for later retrieval and analysis

Image analysis and computer vision: 1989

Abstract: This paper presents a bibliography of nearly 1200 references related to computer vision and image analysis, arranged by subject matter. The topics covered include architectures; computational techniques; feature detection, segmentation, and image analysis; matching, stereo, and time-varying imagery; shape and pattern; color and texture; and three-dimensional scene analysis. A few references are also given on related topics, such as computational geometry, computer graphics, image input/output and coding, image processing, optical processing, visual perception, neural nets, pattern recognition, and artificial intelligence.

Three-dimensional reconstruction of stenosed coronary artery segments with assessment of the flow impedance

Abstract: In this paper preliminary results of a study about the diagnostic benefits of 3D visualization and quantitation of stenosed coronary artery segments are presented. As is well known, even biplane angiographic images do not provide enough information for binary reconstruction. Therefore,a priori information about the slice to be reconstructed must be incorporated into the reconstruction algorithm. One approach is to assume a circular cross-section of the coronary artery. Hence, the diameter is estimated from the contours of the vessels in both projections. Another approach is to search for a solution of the reconstruction problem close to the previously reconstructed adjacent slice. In this paper we follow the first method based on contour information. The reconstructed coronary segment is visualized in three dimensions. Based on the obtained geometry of the obstruction the pertinent blood flow impedance is estimated on the basis of fluid dynamic principles. The results of applying the reconstruction algorithms to clinical coronary biplane exposures are presented with an indication of the assessed flow impedance.

A complete and scalable architecture for 3D model-based vision

Abstract: As a follow-up to the work of R.M. Bolle et al. (Proc. DARPA Image Understanding Workshop, May 1989, p.477-8), an overview is given of subsequent work. The focus of the ongoing work is the development of an experimental vision system for recognition of 3D objects. The thrust of this vision system is to investigate techniques that may lead to a system that scales with the size of the problem (by the size of the problem, the authors mean the complexity of the scene-the number of objects in the scene and the number of objects in the database, i.e. the number of objects that the system can recognize). One important aspect of the work is representing 3D shapes and objects, and storing these representations in object-model databases. Another aspect is the control of the search, i.e. finding good intermediate representations of the data and using these representations to index into the object-model database. >

Multiple stereo vision for 3D object reconstruction

Abstract: A vision system for 3D information extraction and surface reconstruction of objects in a robot workspace is described. The system consists of N cameras arranged in an N /2 periodic stereo pair structure. The surface reconstruction is performed in two stages. The 3D data from different perspectives are inferred independently using a periodic stereo structure, and then the extracted information from neighboring camera pairs is used to reconstruct the surface of the object

A multiresolution approach to the 3D reconstruction of a 50S ribosome from an EM-tilt series solving the alignment problem without gold particles (electron microscopy)

Abstract: A multiresolution approach to 3D reconstruction from an electron microscope (EM) tilt series is presented. It is designed for reconstruction from a tilt series with a limited number of projections where the tilt angles are assumed to be known. Its main feature is that it solves the alignment problem very accurately from the image data without additional gold particles, including the determination of translational, orientational, and scaling parameters. The approach relies on a coarse-to-fine bootstrap control strategy based on the observation that with an appropriate matching procedure good alignment estimates can be obtained at a rather coarse level of resolution. This serves for a better reconstruction of the next finer level, from which a further refinement of the alignment estimate is obtained, etc. The actual reconstruction at each level of resolution is accomplished with a synthesis of the filtered back-projection method and iterative algebraic techniques, together with a set of convex constraints. The complete algorithm is applied to an EM tilt series of a 50S ribosome prepared in ice, consisting of 11 micrographs. >

A computational model for dynamic vision

Abstract: This paper describes a novel computational model for dynamic vision which promises to be both powerful and robust. Furthermore the paradigm is ideal for an active vision system where camera vergence changes dynamically. Its basis is the retinotopically indexed object-centered encoding of the early visual information. Specifically, the relative distances of objects to a set of referents is encoded in image registered maps. To illustrate the efficacy of the method, it is applied to the problem of dynamic stereo vision. Integration of depth information over multiple frames obtained by a moving robot generally requires precise information about the relative camera position from frame to frame. Usually, this information can only be approximated. The method facilitates the integration of depth information without direct use or knowledge of camera motion.

A Multi-Resolution Approach to the 3D Reconstruction of a 50s Ribosome from an EM-Tilt Series Solving the Alignment Problem without Gold Particles

Abstract: multi-resolution approach to the 3D-reconstruction prob- lem from electron microscope tilt series is presented. It is designed for the reconstruction from a tilt series with a limited number of projections where the tilt angles are as- sumed to be known. Its main feature is that it solves the alignment problem very accurately from the image data without additional gold particles-including the determina- tion of translational, orientational, and scaling parameters. At the core of the approach there is a coarse-to-fine boot- strap control strategy based on the observation that with an appropriate matching procedure good alignment esti- mates can be obtained at a rather coarse level of resolu- tion. This serves for a better reconstruction at the next finer level, from which a further refinement of the align- ment estimate is obtained, etc. The actual reconstruction at each level of resolution is accomplished with a synthesis of the filtered back-projection method and iterative alge- braic techniques, together with a set of convex constraints. The complete algorithm is applied to an EM tilt series of a 50s ribosome prepared in ice, consisting of 11 micrographs. Introduction standard technique for the reconstruction of 3D densi- ties from electron microscope tilt series is the filtered back- projection method (l-31. There are two apparent problems with this concept, arising from the requirement of com- plete information from all directions, and precise alignment of the projections as a precondition of the filtered back- projection. The first is the "missing cone" problem due to the maxi- mum tilting angle of 60 degrees in an electron microscope. Various approaches have been proposed in order to over- come this problem. It can be solved with the a priori knowlledge of symmetries of the object or other regular- izing constraints (4). It has also been shown that the range of -60...+60 degrees is sufficient in ma cases even for asym-

Future directions in computer vision and image understanding; ETL perspectives

Abstract: Research work dealing with some of the problems in computer vision (CV) and image understanding (IU) is described. Attention is given to progress in CV and IU involving active range finders, passive stereo sensing, 3D reconstruction, 3D scene analysis, dynamic scene analysis, automatic knowledge acquisition for model- and strategy-based systems, and autonomous vision systems. >

Depth Cues From Optical Flow

Abstract: In order to have a perfect computer vision system, it is important that it should emulate something which is already prefect - the human visual system. In this paper we discuss the relevancy of the study of the psychological and physiological aspects of human vision to computer vision research. Motion perception is an important aspect of vision. We make an approach here, to configure a system that can perceive world knowledge from moving scenes. This is based on the principle that moving scenes generate optical flow and getting the depth cues from optical flow gives three dimensional information of the scene. We derive depth information from passive ranging techniques. Potential applications are in autonomous vehicle navigation, coordinated motions between vehicles for passive ranging to moving targets and in industrial robotics.

Computer graphics testbed for developing and testing laser-imaging algorithms

Abstract: This paper describes the use of computer graphics modeling to simulate laser range and reflectance images. Applications of image processing techniques to computer-generated (C-G) laser images are described and advantages of this system over a physical device are discussed. An example is presented in which laser imaging algorithms are developed and applied to robotic navigation.

Computer Vision Analysis of Boundary Images

Abstract: This chapter gives a brief introduction to the field of computer vision by describing different approaches to computer vision research, and then illustrates several of the approaches by describing some current research concerned with the computer analysis of boundary images.

Three-dimensional reconstruction of solid models from multi-directional images and applications to industrial mensuration

Abstract: An automated modeling system that represents an object body by a solid model of polyhedral approximation was developed using multi-directional image inputs. The principle of this solid model generation is based on the calculation of viewing pyramids consisting of the image boundary and the corresponding focal point. Applications to the non-contacting three-dimensional measurement of the shape of irregular and complicated object such as a doll, a fish, a spiral shell, and a lemon, to the automated mesh generation for the boundary element analysis of the lemon, to the CAD of a tillage blade, and to the shape, deformation and motion analysis of an aerodynamic tuft, a small tracer particle, and an alcohol wick flame for the flow visualization are presented. It appears to have considerable utility in bio-mechanics and various industrial applications.

Reconstruction of biomedical objects by tiling

Abstract: The 3D reconstruction of biomedical objects from 2D images has gained widespread attention. Several methods for reconstructing surfaces by triangulation are examined. These techniques has been specifically applied to the three dimensional reconstruction of biomedical objects from serial slices. The advantages and disadvantages of each method are considered, and a new method is described which is superior to existing practices.

3-D blood vessel reconstruction by simulated annealing

Abstract: Simulated annealing a Monte Carlolike algorithm is applied to 3D blood vessel reconstruction based on digital subtraction angiography(DSA). Since the imaging system is highly illposed because of the insufficient number of projections good reconstruction can not be achieved with only the observed data. This paper shows that even in such cases objects can be well reconstructed by simulated annealing making use of constraints based on a priori knowledge. The performance of this method for photon noise and the feasibility of 3D reconstruction are discussed through some computer simulations. 1.

Advances On Integration Between Stereo Sparse Data And Orientation Map

Abstract: During last years, Computer Vision has developed algorithms for most of early vision processes. It is a common idea that each vision process seaparatly cannot supply a reliable descritpion of the scene. In fact, one of the keys in reliability and robustness of biological systems is their ability to integrate information from different early processes. The base concept of our vision system is to integrate information from stereo and shading (Fig.1). The results obtained from this scheme in previous works are very interesting and suggest us to continue on this methodology. In the first work 1.2 the base approach to integration scheme was presented. The work deals on general concepts and main evolutions on shading analysis, in terms of analysis simplifications and improved accuracy. The scheme was tested on both synthetical and real scenes.

3-D reconstruction using a limited number of projections

Abstract: We present a new iterative algorithm for 3D reconstruction under constraints from a limited number of radiographic projections with adjustment of the constraints during the iterations. The first step of the algorithm is a classical iterative reconstruction ART type method (Algebraic Reconstruction Technique) which provides a rough volumic reconstructed 3D zone containing a flaw. Then this reconstructed zone is modelled by a Markov Random Field (MRF) which allows us to estimate some 3D support and orientation constraints using a Bayesian restoration method. This fundamental step is an important one in the sense that it allows the introduction of local geometric a priori knowledge concerning the faults. The next step consists in reintroducing these strong constraints in the reconstruction algorithm. Few iterations of the algorithm are necessary to improve quality of the reconstructed 3D zone. Simulated radiographic projections allow the performance of the algorithm to be evaluated© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.