Showing papers on "Perspective (geometry) published in 2009"

Perspective 3-D Euclidean Reconstruction With Varying Camera Parameters

Abstract: The paper addresses the problem of 3-D Euclidean structure and motion recovery from video sequences based on perspective factorization. It is well known that projective depth recovery and camera calibration are two essential and difficult steps in metric reconstruction. We focus on the difficulties and propose two new algorithms to improve the performance of perspective factorization. First, we propose to initialize the projective depths via a projective structure reconstructed from two views with large camera movement, and optimize the depths iteratively by minimizing reprojection residues. The algorithm is more accurate than previous methods and converges quickly. Second, we propose a self-calibration method based on the Kruppa constraint to deal with more general camera model. The Euclidean structure can be recovered from factorization of the normalized tracking matrix. Extensive experiments on synthetic data and real sequences are performed to validate the proposed method and good improvements are observed.

Calibration of a profile measuring system

Abstract: A method for calibrating a measuring system, which system comprises a structured light source, optics and a sensor. The light source is adapted to produce a light plane or sheet and the optics is located between the light plane and the sensor. The method is performed in order to obtain a mapping from the sensor to the light plane. In the method the light source is switched on such that the light plane is produced. In order to account for distortions due to the optics, a mapping calibration profile is introduced in the light plane, wherein the mapping calibration profile comprises at least three points forming a straight line. A non-linear mapping from the sensor to the light plane is then computed by using the at least three points. Next, in order to account for perspective distortions, a homography calibration profile is introduced in the light plane, wherein the homography calibration profile comprises at least four points the relative distance between which are predetermined. A homography from the sensor to at the light plane based on these four points is then computed. A calibration object for using in such a method is also presented.

Field calibration method of structural parameter of line structure light vision sensing system

Abstract: The invention provides a field calibration method of the structural parameter of a line structure light vision sensing system, comprising the following steps: (a) a movable plane target is put in a measured space, a collinear and three characteristic points with known mutual distance are arranged on the plane target, and the light plane which is projected by a line structure light projector intersects with the straight line at which the three are positioned so as to form a fixed point; (b) the collinear three characteristic points are used for setting up a three-point perspective model, and according to the mutual distances of the three characteristic points, the picpointed coordinates which are imaged on the image surface of a television camera by the three characteristic points and the fixed point, and the internal parameter of the television camera, the coordinate of the fixed point in the coordinate system of the television camera is computed; (c) the plane target is moved to many different positions within measuring range so as to respectively form a plurality of additional fixed points, and the step (b) is repeatedly carried out so as to respectively compute the coordinates of the additional fixed points in the coordinate system of the television camera; and (d) the fixed points which are obtained at many times are fitted into a plane so as to obtain the plane equation of the light plane in the coordinate system of the television camera, thereby completing the field calibration.

Digital camera calibration analysis using perspective projection matrix

Abstract: This work presents a novel and simplified technique to estimate the perspective projective matrix elements of calibration matrix for pinhole model in Digital Camera Calibration. The "perspective projective matrix parameters" are variables depending of environmental changes and position and/or orientation camera so we propose a dynamical and stochastic method to model the uncertain in the parameters estimation. It is well suited for use without specialized knowledge of 3D geometry or computer vision. Two morphological matrix operations are introduced: Central(Xk, Yk) and Column(Mk) to generalize the process which obtain the estimated parameters based on pseudo-inverse calculus without consider measures errors, this calibration procedure focus only on perspective projective matrix elements. The mean value respect to 3D points and 2D points used as input information. The theoretical results give a good enough approximation result considering the pseudo-inverse matrix calculus method. In the same sense, the experimental results showed a satisfactory advance in the parameters stochastic estimation theory, respect to velocity change gains.

Rough Geometry and Its Applications in Character Recognition

Abstract: The absolutely abstract and accurate geometric elements defined in Euclidean geometry always have lengths or sizes in reality. While the figures in the real world should be viewed as the approximate descriptions of traditional geometric elements at the rougher granular level. How can we generate and recognize the geometric features of the configurations in the novel space? Motivated by this question, rough geometry is proposed as the result of applying the rough set theory to the traditional geometry. In the new theory, the geometric configuration can be constructed by its upper approximation at different levels of granularity and the properties of the rough geometric elements should offer us a new perspective to observe the figures. In this paper, we focus on the foundation of the theory and try to observe the topologic features of the approximate configuration at multiple granular levels in rough space. Then we also attempt to apply the research results to the problems in different areas for novel solutions, such as the applications of rough geometry in the traditional geometric problem (the question whether there exists a convex shape with two distinct equichordal points) and the recognition work with principal curves. Finally, we will describe the questions induced from our exploratory research and discuss the future work.

A new practical strategy to localize a 3D object without sensors

Abstract: Sensorless localization of 3D objects has been a significant research topic for many years. Researchers have focused on this problem from both theoretical and practical perspective where the goal is to reduce uncertainties in the orientation of a 3D object. However, to the best of our knowledge, no effective practical methods have been proposed so far to localize a polyhedron from any initial orientation to a unique orientation without sensors. In our previous work [1], two broad classes of 3D objects have been introduced, which can be localized from an arbitrary state to a unique state on a flat plane (the surface resting on the flat plane is established) without sensors. In this paper, a much broader class of polyhedra is introduced, which can be localized to a unique state without sensors. The main contributions of this paper are given as follows: • It is found that a polyhedron with an arbitrary initial state on the flat plane can be rotated to a fixed orientation (the orientation of the surface resting on the flat plane is fixed), provided that the polygon corresponding to each surface of the polyhedron can be oriented to a unique orientation in a 2D space. The method of rotating the polyhedron to a fixed orientation is given. • Base on the above result, both conditions and the strategy are given for a polyhedron to be localized to a unique state. • An example is given to show the validity of the strategy.

Unidirectional Computational Integral Imaging Technique for Perspective Plane-Image Reconstruction of Three-Dimensional Objects

Abstract: This paper presents a computational integral imaging (CII) technique based on a unidirectional reconstruction to provide perspective plane images of three-dimensional (3D) objects for occluded object recognition and visualization. CII has been widely investigated for 3D passive imaging systems. However, the conventional CII method provides only front-view plane images along the z axis. In this paper, we propose a new computational method to reconstruct perspective-view plane images of 3D objects. We introduce unidirectional elemental images extracted from original elemental images. The unidirectional elemental images produced by our method with respect to an observation angle are utilized to reconstruct various perspective plane images. Experimental results indicate the efficacy of the proposed method. Also, the proposed method is performed fast due to the nature of the unidirectional processing.

Method for informing a passenger of a vehicle

Abstract: The invention relates to a method for informing a passenger of a vehicle, wherein at least two images (102, 103, 103') are generated via recording means (2, 3, 4) of the vehicle (1), said images containing different road sections of the road plane within the vicinity of the vehicle (1), and wherein the at least two images (102, 103, 103') are processed by an imaging processing device and are displayed on a display device (5) in the vehicle interior, characterized in that an illustration is generated wherein the at least two images (102, 103, 103') are displayed on a virtual road plane, wherein the virtual road plane is displayed in a perspective manner.

Projective Architecture

Abstract: Michele Sbacchi investigates the real influence of the notion of projection on architectural design before and during the age of Guarini. He takes into consideration concepts such as light and shadow, abstract line, plane, section, projective geometry and perspective. To do this he looks at the ideas of Gregorius Saint Vincent, Alberti, Guarini, Desargues and de l’Orme, among others.