Showing papers on "3D reconstruction published in 1989"

Computer graphics for cellular reconstruction

Abstract: The use of computer graphics to study the three-dimensional structure of tissues within an organism such as a human is considered. A system called Sterecon, which uses stereo views of thick sections of tissues and a high-voltage electron microscope, is described. Contours of structures are traced in stereo and entered into a graphics database. Using thick sections decreases the work by ten- to twenty-fold. The database can be manipulated to display cellular organization using various graphics representations. >

Computational geometric methods in volumetric intersection for 3D reconstruction

Abstract: The authors presents an approach to the generation of 3D models of arbitrarily shaped physical objects. These models can be used for purposes of manipulation as well as such tasks as collision avoidance and workspace mapping. The technique utilizes a set of images taken from known view positions, from which the silhouettes of the objects are extracted. These silhouettes (occluding contours) are then projected along the view vector to form 3D conics. Mutual intersection of the set of conics formed from the images generates an approximate model of the object. The techniques used to intersect the conics draw on algorithms used in computational geometry. The model becomes more refined as more images are used. The objects are modeled by contours on successive parallel planes. The contour model supports the ability to generate the surface of the object by tessellation. >

Image Intensifier-Based CT Volume Imager For Angiography: System Evaluation

Abstract: A prototype volume CT system for use in angiography has been modified and tested using three different phantoms. This system consists of a fixed x-ray tube, a conventional image intensifier coupled to a charge-coupled device (CCD) camera, a computer-controlled turntable on which phantoms were placed. In order to explore the imaging performance of the system for reconstructing a three dimension (3D) vascular structure, two sets of projection images of a vascular phantom, acquired over 250 projection angles with two different sizes of image intensifier were digitized and used for a direct 3D cone beam reconstruction. The spatial resolution limits of the system were measured from the 3D reconstructed images of a specially-designed resolution phantom. The direct 3D reconstructions of a Humanoid chest phantom were obtained using this system to show the perspective of the system for a general medical application with 3D imaging. The quality of the reconstructed images indicates that the system can be used for achieving a direct 3D reconstruction of a vascular structure as well as a general 3D object. The measured spatial resolution of the system is nearly half of the nominal resolution of the image intensifier and is reduced around the edge of the image intensifier, primarily because of the pincushion distortion.

A Knowledge-Based System For The 3D Reconstruction And Representation Of The Cerebral Blood Vessels From A Pair Of Stereoscopic Angiograms

Abstract: This paper presents work in progress concerning an automatic system for the 3D reconstruction and representation of the cerebral vessels. It is based on a separate delineation of the blood vessels in two stereo images. First, we extract blood vessel segments from the image and subsequently we use those high level primitives to guide the stereoscopic matching process. Therefore, we make extensive use of domain specific knowledge like the orientation, thickness and intensity of blood vessels.

Computer vision and shape recognition

Abstract: This is an up-to-date volume of selected and expanded papers originating from Vision Interface 88, a conference held in Edmonton, Canada. A broad range of topics are covered-from image processing to hardware design. They include robot vision, biomedical imaging, remote sensing and parallel processing, shape recognition and features, computational methods in vision, and three dimensional vision and application.

Automatic Modelling of Rigid 3D Objects Using an Analysis by Synthesis System

Abstract: An important computer vision task is modeling of 3D objects for computer graphics and animation. This paper presents a method for generating a 3D wireframe model automatically out of a number of views of the original object. The silhouettes of the objects are used to determine the intersecting volume which represents a rough estimation of the object shape in voxel representation. A triangulation algorithm converts the model into a wire-frame surface representation to enhance the quality of the models surface and allow tex-ture mapping. A shape from motion/stereo algorithm is used to enhance the model shape. Calibrated cameras are used to obtain true dimensions.

[Prerequisites for the clinical application of 3-dimensional ultrasonic imaging].

Abstract: After satisfactory experimental results with three-dimensional data acquisition and presentation of the kidney in vitro, we wanted to show how our technique could be used for medical application in vivo, such as ultrasonic 3D reconstruction of organs. The sector scans were taken by rotating the scan head 10 degrees in any direction around the length of the axis. The organ was scanned with 18 images and reconstructed. The digital images, using the organ contours, allowed 3D reconstruction of the original organ, relying on the computer memory. The first results in reconstructing uteri show how this scan head can be used in combination with the computer programs for medical application. For the first time, it has become possible to present computer-generated views of an organ cross-section that has been impossible to obtain by means of traditional ultrasound techniques. Recent experiments using this method show new ways of diagnosing tumors.

Automatic 3D-reconstruction of vascular networks from three projections: a simulated annealing approach

Abstract: The problem of 3-D reconstruction from three digital angiographs is discussed. The solution described is based on trinocular vision and performs the matching of segments. All the pairing possibilities are first defined using geometrical constraints and a global control is applied through a simulated annealing algorithm. The method has been tested on simulated images and on real images of a wire-heart phantom. The results were judged very promising. >

Three-Dimensional Surface Reconstruction Software System for IBM Personal Computers

Abstract: Surface and volumetric three-dimensional imaging methods have found application in fields as diverse as diagnostic medical imaging and paleontological research The acquisition, modeling, classificati

Monocular computer vision

Abstract: The human visual system is usually able to recognize objects as well as their spatial relations without the support of depth information like stereo vision. For this reason one can easily understand cartoons, photographs and movies. It is the aim of the authors' current research to exploit this aspect of human perception in the context of computer vision. From a monocular TV image one obtains information about the type of an object observed in the scene and its position relative to the camera (viewpoint). This paper deals with the theory of human image understanding as far as used in this system and describes the realization of a vision system based on these principles.< >

Microcomputer-based system for 3D reconstruction, analysis and 3D animation of the heart and its coronary arteries

Abstract: A system for 3D reconstruction, analysis, and dynamic animation of the heart and the coronary arteries was developed on an IBM/PC-compatible computer. The system utilizes data from MRI (magnetic resonance imaging), cine-CT (computer tomography), ultrasound, or angiography. The endocardium and epicardium of both the left and right ventricles are first traced from the video monitor. Three-dimensional reconstruction is done from planar slices (MRI, CT) or long axis images (echocardiography). The coronary tree is superimposed on the 3D epicardial surface by means of anatomical markers. The location and severity of the stenosed vessels are then marked. Graphical capabilities include dynamic animation, wireframe, solid shading, semitransparent shading, color mapping of the 3D shape according to local function, and anatomical cross-sectional views. Analysis of global and local ventricular function is achieved by calculating LV volume, ejection fraction, regional thickening, and wall motion. >

Microcomputer based system for 3D reconstruction, simulation and dynamic animation of the heart

Abstract: A system for 3-D reconstruction, analysis, simulation and dynamic animation of the heart and the coronary arteries is reported. Using magnetic resonance cross-sectional or ultrasonic and angiographic long-axis imagers of the heart, the endocardial and epicardial contours are traced, interpolated and reconstructed in 3-D. The coronary tree is then superimposed on the 3-D shape using anatomical markers. Graphical capabilities include real-time animation, utilizing wire-frame, solid shading, semitransparent shading and different viewing angles. Simulation of geometrical deformations caused by variations in the arterial flow is achieved by defining the risk area of each coronary vessel, the flow-thickening relationship function and the actual relative flow in the simulated stenosed vessel and using these to simulate local ischemia by varying the dynamic 3-D shape of a normal heart. Assessment of local myocardial function is achieved by calculating local parameters such as thickening or wall motion. >

3D Reconstruction and Recognition from Multiple Views and with Different Acquisition Constraints

Abstract: Two techniques for 3D object reconstruction from a sequence of 2D images are described. The first one is based on a set of pictorial calibrated images and exploits the occluding contours to yield both a volumetric and a pictorial reconstruction. In the second technique a limited volumetric information is obtained by estimating the motion of a set of rigidly connected corresponding points extracted from the sequence of 2D views. The integration of the above techniques is discussed and some experimental results are presented.

Cooperation Between Stereo-vision And A Token Tracker Process For The 3d Vision Of A Mobile Robot

Abstract: We present a 3D vision sensor for a mobile robot. The sensor builds a description of the environment based on 3d vertical straight line segments. It operates as a cooperation between a stereovision process and a token tracking process. A full matching process is performed at the initialization step. Then the token tracker allows to maintain the same matches that were established previously. The sensor has only to find out matches on the new tokens lhat were detected. We use a procedure based on the dynamic programming to find out these new matches. This procedure takes advantage of the already existing matches to perform this task rapidly. 1- IntrodA mobile robot has to construct a description of its environment €or the navigation task. This description has to be built continuously and should not enforce the robot to stop during this task. We present a 3D stereo-based sensor that will be on board of a mobile robot used for surveillance of industrial sites. It constructs a description of the environment based on 3d vertical straight line segments. The restriction to vertical straight lines is reasonable in the sense that the sensor will be used only for the navigation task. We aim to reduce the complexity and to increase the speed of the algorithms. Indeed (i) the amount of segments to be processed is reduced, (ii) the verticality hypothesis drastically simplifies the algorithms. Anyway, the poor description of the environment will be fused with depth informations provided by the sonar sensors. -171 The functioning of the sensor is based on the combination of two processes : a stereo matching process and a token tracking process. The stereo matching process is useful for the 3D reconstruction. It embodies the actual 3D capability of the sensor. The token tracking process deals with the image changes due to the robot motion. The main problem for the stereo matching process comes from the socalled stereo - c or r e s p o n de nc e problem. Robustness is often paid by a very time consuming matching process. The basic idea of the sensor described in this paper is to take advantage of the token tracking process to aid the stereo process. It relies on the previous detected correspondences to rapidly compute those of the current image stereo pair.

Topological Model Based Method For 3D Reconstruction Of Surfaces. Application : Cardiac Imaging

Abstract: We expose a pretopological model based method for 3D reconstruction of surfaces. Pretopology provides concepts and results which enable us to reconstruct 3D surfaces betwen slices by mean of connectivity criteria and of what we call "addable points". First experimental results in the field of cardiac imaging are presented and discussed.