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Showing papers on "Perspective (geometry) published in 2011"


Patent
Alexander Augst1
19 Jan 2011
TL;DR: In this paper, a recording unit of a vehicle generates at least two images, which contain different road sections of a road plane in the surroundings of the vehicle, which are processed by an image processing unit, which generates a depiction in which the at least 2 images are imaged on a virtual road plane that is displayed in perspective.
Abstract: Methods and apparatuses for informing an occupant of a vehicle of surroundings of the vehicle are provided. A recording unit of the vehicle generates at least two images, which contain different road sections of a road plane in the surroundings of the vehicle. The at least two images are processed by an image processing unit, which generates a depiction in which the at least two images are imaged on a virtual road plane that is displayed in perspective. The depiction is displayed on a display unit in the interior of the vehicle.

50 citations


Journal ArticleDOI
TL;DR: The proposed method use foreground pixels from simple background subtraction to compute evidence of the location of people on a reference ground plane by combining evidence from multiple cameras using the homography constraint.

34 citations


Journal ArticleDOI
Marc Frantz1
TL;DR: In this article, the authors apply Eves's theorem to accident scene reconstruction, to the circular products in the theorems of Ceva and Menelaus, and to perspective illustrations of the geometric mean.
Abstract: Though not well known, Eves�s theorem is a fundamental result of projective geometry�a tool as versatile as a Swiss Army knife. Named for the late Howard W. Eves (1911�2004), the theorem establishes a class of numerical projective invariants, of which the famous cross ratio is a special case. We illustrate the versatility of Eves�s theorem by applying it to accident scene reconstruction, to the circular products in the theorems of Ceva and Menelaus, and to perspective illustrations of the geometric mean. In addition, we show that the theorem is illustrated by everyday photographs of buildings and other common objects.

3 citations


Proceedings Article
01 Jan 2011
TL;DR: An object-based and a camera-based computer graphics procedure to prevent projective distortions and misalignments are introduced to provide humancentered interfaces for an efficient and coherent communication of spatial information in virtual worlds.
Abstract: Projection of three-dimensional space onto a two-dimensional surface relies on the computer graphics camera based in design on the camera obscura. Geometrical limitations of this model lead to perspective distortions in wide-angle projections. Including the camera model, our approach is to involve the human perception in order to create a realistic spatial impression by a two-dimensional image. The aim is to provide humancentered interfaces for an efficient and coherent communication of spatial information in virtual worlds to support avatar-mediated interaction with its need for correct depiction of human figures concerning proportion and orientation. To this end, we explain an object-based and introduce a camera-based computer graphics procedure to prevent projective distortions and misalignments.

2 citations


29 Dec 2011
TL;DR: In this paper, a special attention is given to the conditions which basic elements of perspective collineation have to fulfill in order to obtain the touch or osculation of two conics.
Abstract: All perspective collineations in a real affine plane are classified according to a constant cross-ratio and the position of the center and axis. A special attention will be given to the conditions which basic elements of perspective collineation have to fulfill in order to obtain the touch or osculation or hyperosculation of two conics. On the affine models of an isotropic and pseudo Euclidean plane the osculating circle of a conic is constructed by using perspective collineations.

2 citations


Journal ArticleDOI
TL;DR: This work introduced a technique based on the concept of multiple hypothesis tracking with a motion-smoothness function between consecutive frames to automatically find the optimal solution for this ill-posed problem of reconstruction from 2D to 3D.
Abstract: A novel method is proposed to estimate the 3D relative positions of an articulated body from point correspondences in an uncalibrated monocular image sequence. It is based on a camera perspective model. Unlike previous approaches, our proposed method does not require camera parameters or a manual specification of the 3D pose at the first frame, nor does it require the assumption that at least one predefined segment in every frame is parallel to the image plane. Our work assumes a simpler assumption, for example, the actor stands vertically parallel to the image plane and not all of his/her joints lie on a plane parallel to the image plane in the first frame. Input into our algorithm consists of a topological skeleton model and 2D position data on the joints of a human actor. By geometric constraint of body parts in the skeleton model, 3D relative coordinates of the model are obtained. This reconstruction from 2D to 3D is an ill-posed problem due to non-uniqueness of solutions. Therefore, we introduced a technique based on the concept of multiple hypothesis tracking (MHT) with a motion-smoothness function between consecutive frames to automatically find the optimal solution for this ill-posed problem. Since reconstruction configurations are obtained from our closed-form equation, our technique is very efficient. Very accurate results were attained for both synthesized and real-world image sequences. We also compared our technique with both scaled-orthographic and existing perspective approaches. Our proposed method outperformed other approaches, especially in scenes with strong perspective effects and difficult poses.

2 citations


Patent
24 Mar 2011
TL;DR: In this paper, an apparatus for detecting an object and method thereof are provided to efficiently detect and trace a moving object using a perspective plane, and the movement of the detected object is traced.
Abstract: PURPOSE: An apparatus for detecting an object and method thereof are provided to efficiently detect and trace a moving object using a perspective plane. CONSTITUTION: A perspective plane is established for a background scene(S100). A filter value corresponding to an object detection minimum size, and the established perspective plane(S120). A moving object in the background scene is detected(S130). In the background scene, the movement of the detected object is traced(S140).

2 citations


Proceedings Article
01 Jan 2011
TL;DR: This paper presents a new approach to solve the classic perspective-three-point (P3P) problem by searching for the maximum likelihood on the Gaussian hemisphere by exploiting the geometric constraints of three known angles and length ratios from the control points.
Abstract: This paper presents a new approach to solve the classic perspective-three-point (P3P) problem. The basic conception behind is to determine the support plane, which is defined by the three control points. Computation of the plane normal is formulated as searching for the maximum likelihood on the Gaussian hemisphere by exploiting the geometric constraints of three known angles and length ratios from the control points. The distances of the control points are then computed from the normal and the calibration matrix by homography decomposition. The proposed algorithm has been tested with real image data. The computation errors for the plane normal and the distances are less than 0.35 degrees, and 0.8cm, respectively, within 1~2m camera-to-plane distances. The multiple solutions to P3P problem are also illustrated.

1 citations


Proceedings ArticleDOI
22 May 2011
TL;DR: A novel probabilistic approach to handle occlusions and perspective effects for the size estimation of a penguin colony is introduced, an object based method embedded in a marked point process framework.
Abstract: In this paper, we introduce a novel probabilistic approach to handle occlusions and perspective effects. The proposed method is an object based method embedded in a marked point process framework. We apply it for the size estimation of a penguin colony, where we model a penguin colony as an unknown number of 3D objects. The main idea of the proposed approach is to sample some candidate configurations consisting of 3D objects lying in the real plane. A Gibbs energy is define on the configuration space. These configurations are projected onto the image plane to define the data term, to which some prior information is added. The configurations are modified until convergence using the multiple birth and death optimization algorithm and by measuring the similarity between the projected image of the configuration and the real image. During optimization, the proposed configuration is modeled by a mixed graph which represents all dependencies between the objects, including interaction between neighbor objects and parent-child dependency for occluded objects. We tested our model on synthetic image, and real images.

1 citations


Dissertation
24 Oct 2011
TL;DR: A novel probabilistic approach to handle occlusions and perspective effects is proposed, which combines the recently developed optimization algorithm Multiple Births and Deaths and the Graph-Cut and is compared to the MBD and MBC algorithms.
Abstract: The topic of this thesis is to develop a novel approach for 3D object detection from a 2D image. This approach takes into consideration the occlusions and the perspective effects. This work has been embedded in a marked point process framework, proved to be efficient for solving many challenging problems dealing with high resolution images. The accomplished work during the thesis can be presented in two parts. First part: we propose a novel probabilistic approach to handle occlusions and perspective effects. The proposed method is based on 3D scene simulation on the GPU using OpenGL. It is an object based method embedded in a marked point process framework. We apply it for the size estimation of a penguin colony, where we model a penguin colony as an unknown number of 3D objects. The main idea of the proposed approach is to sample some candidate configurations consisting of 3D objects lying on the real plane. A Gibbs energy is define on the configuration space, which takes into account both prior and data information. The proposed configurations are projected onto the image plane, and the configurations are modified until convergence. To evaluate a proposed configuration, we measure the similarity between the projected image of the proposed configuration and the real image, by defining a data term and a prior term which penalize objects overlapping. We introduced modifications to the optimization algorithm to take into account new dependencies that exists in our 3D model. Second part: we propose a new optimization method which we call "Multiple Births and Cut" (MBC). It combines the recently developed optimization algorithm Multiple Births and Deaths (MBD) and the Graph-Cut. MBD and MBC optimization methods are applied for the optimization of a marked point process. We compared the MBC to the MBD algorithms showing that the main advantage of our newly proposed algorithm is the reduction of the number of parameters, the speed of convergence and the quality of the obtained results. We validated our algorithm on the counting problem of flamingos in a colony.

1 citations


Book ChapterDOI
19 Dec 2011
TL;DR: The obtained results classify projection out of counterfactuals as a reliable test for projective meanings in the cross-linguistic perspective, while shedding more light on the semantics of nur and conditionals, on the other.
Abstract: The paper presents the results of the experiment on the projective meaning of nur (German: only). The data from German shows that the prejacent of nur projects easily out of counterfactual if-clauses, whereas its projective behaviour changes when it is embedded in indicative if-clauses. The obtained results classify projection out of counterfactuals as a reliable test for projective meanings in the cross-linguistic perspective, on the one hand, while shedding more light on the semantics of nur and conditionals, on the other.