2D line and polygon clipping based on space subdivision

This paper introduces a new approach to 2D line and polygon clipping against a rectangular clipping region, using space subdivision into cells, with the clipping region as the central cell. The line segment path is traced through the cells, and entries into and out of the cell corresponding to the clipping region enable computation of the intersection of the line segment with crossed cell edges. Tracing the line segment path is computationally very simple, leading to an algorithm that only computes intersections that the are part of the clipped line segment. The new algorithm is compared to other standard line clipping algorithms with simulations and operation counts.     

A New Algorithm for Two-Dimensional Line Clipping via Geometric Transformation

Line segment clipping is a basic operation of the visualization process in computer graphics.So far there exist four computational models for clipping a line segment against a window,(1)the encoding,(2)the parametric,(3)the geometric transforma tion,and (4)the parallel cutting.This paper presents an algorithm that is based on the third method.By making use of symmetric properties of a window and transformation operations,both endpoints of a line segment are transformed,so that the basic cases are reduced into two that can be easily handled,thus the problems in NLN and AS where there are too many sub-procedure calls and basic cases that are difficult to deal with are tackled.Both analytical and experimental results from random input data show that the algorithm is better than other developed ones,in view of the speed and the number of operations.     

A new approach to parametric line clipping

Line clipping is an important operation in almost every graphical application. The most commonly used techniques are based on line end point encodings or the parametric representation of straight line segments. In this paper both techniques are combined in a new algorithm that computes accurately rounded coordinates, without the use of any floating point operations. It is shown that the new method is suited for implementations in software as well as in hardware. A performance study of the new and several other well-known line clipping algorithms indicates the superiority over all other examined algorithms.     

Fast algorithms for clipping lines and line segments in E2

E ² are presented. The suggested algorithms are based on a technique of coding the line direction together with the end points of the clipped line segment. They solve all cases more effectively. The algorithms are convenient for clippings lines or line segments by rectangle. Theoretical considerations and experimental results are also presented.     

A new approach to 3D reconstruction without camera calibration

In this paper, we present a new approach for 3D scene reconstruction based on projective geometry without camera calibration. Previous works use at least six points to build two projective reference planes. Our contribution is to reduce the number of reference points to four by exploiting some geometrical shapes contained in the scene. The first implemented algorithm allows the reconstruction of a fourth point on each reference plane. The second algorithm is devoted to the 3D reconstruction. We obtained the expected good results and the proposed method is to equip a mobile robot moving in a structured environment.     

A new approach to constructing CSS codes based on factor graphs

A novel, practical and convenient approach to constructing Calderbank-Shor-Steane (CSS) codes based on factor graphs is presented in this paper. Our proposed method is applied to solve two problems associated with constructing CCS codes. One is judging whether a code is a weakly self-dual code or not, the other is finding the generator matrix and parity-check matrix of a weakly self-dual code. The novelty, practicality and convenience of the approach are shown as follows. First, the approach is a hitherto unexplored one to constructing CSS codes. Second, the judgment of a weakly self-dual code is entirely based on factor graphs. Namely, we consider a code a weakly self-dual one when the Tanner graph or convolutional factor graph of its dual code can be obtained by that of its own via our proposed transform T_R→L. Finally, we can obtain the generator matrix and parity-check matrix of a weakly self-dual code via factor graphs other than conventional algebra methods, which allow us avoid matrix computation to get them. An example is given to show how to construct quantum CSS code based on factor graphs. The method can be extended to other CSS codes.     

A bootstrap approach to visual user-interface design and development

An approach to the design of effective computer-based systems is discussed. This approach exploits the user's traditional diagrammatic notations in an effort to achieve usability for experts other than computer professionals. Notations are formalized as visual languages, thus allowing the design of visual editors, interpreters, and compilers. The users themselves exploit these tools to define a hierarchy of environments by a bootstrapping approach. By navigating within these environments, they can progressively design visual interfaces and computing tools that allow them not only to execute the required computational tasks, but also to gain insight into and control the computational process, and check the results.     

A novel virtual node approach for interactive visual analytics of big datasets in parallel coordinates

Big data is a collection of large and complex ​datasets that commonly appear in multidimensional and multivariate data formats. It has been recognized as a big challenge in modern computing/information sciences to gain (or find out) due to its massive volume and complexity (e.g. its multivariate format). Accordingly, there is an urgent need to find new and effective techniques to deal with such huge ​datasets. Parallel coordinates is a well-established geometrical system for visualizing multidimensional data that has been extensively studied for decades. There is also a variety of associated interaction techniques currently used with this geometrical system. However, none of these existing techniques can achieve the functions that are covered by the Select layer of Yi’s Seven-Layer Interaction Model. This is because it is theoretically impossible to find a select of data items via a mouse-click (or mouse-rollover) operation over a particular visual poly-line (a visual object) with no geometric region. In this paper, we present a novel technique that uses a set of virtual nodes to practically achieve the Select interaction which has hitherto proven to be such a challenging sphere in parallel coordinates visualization.     

A new radiosity approach for regular objects: application to ruled surfaces

This paper introduces a new approach in the radiosity method. The main principle applied here, is the improvement of form factor computation by the knowledge of the model properties. More precisely, if surfaces describing a scene are “regular”, the values of the form factor and its “derivatives” between any patch B and a patch A intervening in the meshing of a given surface, enable us to evaluate (with a required precision) the form factors values between B and the neighboring patches of A. We will also show that the mathematical relation we have obtained, 1) is especially efficient with ruled surfaces, 2) significantly decreases the computation time, 3) is well-adapted to refinement or subdivision techniques and 4) gives us an interesting variety of surfaces. Calculation times are equivalent to those obtained with a projective method (hemi-cube for example) but with an efficient control of the generated errors.     

Kinematics and dynamics of a rigid body in nonholonomic coordinates

In this paper we consider dynamic equations of nonholomic systes in terms of pseudo-coordinates which appear in the general theory of rigid body. Especially, the rotator kinematics and dynamics in nonholonomic coordinates is presented. Besides, using the appropriate methods of the differential geometry and theory of Lie groups and Lie algebras a simplification of motion equations in the tangent space is obtained.     

A new approach to discover interlacing data structures in high-dimensional space

The discovery of structures hidden in high-dimensional data space is of great significance for understanding and further processing of the data. Real world datasets are often composed of multiple low dimensional patterns, the interlacement of which may impede our ability to understand the distribution rule of the data. Few of the existing methods focus on the detection and extraction of the manifolds representing distinct patterns. Inspired by the nonlinear dimensionality reduction method ISOmap, in this paper we present a novel approach called Multi-Manifold Partition to identify the interlacing low dimensional patterns. The algorithm has three steps: first a neighborhood graph is built to capture the intrinsic topological structure of the input data, then the dimensional uniformity of neighboring nodes is analyzed to discover the segments of patterns, finally the segments which are possibly from the same low-dimensional structure are combined to obtain a global representation of distribution rules. Experiments on synthetic data as well as real problems are reported. The results show that this new approach to exploratory data analysis is effective and may enhance our understanding of the data distribution.     

A new generalized particle approach to parallel bandwidth allocation

This paper presents a new generalized particle (GP) approach to dynamical optimization of network bandwidth allocation, which can also be used to optimize other resource assignments in networks. By using the GP model, the complicated network bandwidth allocation problem is transformed into the kinematics and dynamics of numerous particles in two reciprocal dual force-fields. The proposed model and algorithm are featured by the powerful processing ability under a complex environment that involves the various interactions among network entities, the market mechanism between the demands and service, and other phenomena common in networks, such as congestion, metabolism, and breakdown of network entities. The GP approach also has the advantages in terms of the higher parallelism, lower computation complexities, and the easiness for hardware implementation. The properties of the approach, including the correctness, convergency and stability, are discussed in details. Simulation results attest to the effectiveness and suitability of the proposed approach.     

IDFC: A new approach to control bifurcation in TCP/RED

The main objective of this research is to analyze the bifurcation phenomenon in Internet congestion model for Transmission Control Protocol (TCP) with Random Early Detection (RED). This problem can be divided to many categories considering different viewpoints. Different approaches of modeling (continuous and discrete models) and various system structures (control in end node or routers) are some of these categories. The most significant method in control of such systems is Delayed Feedback Controller (DFC). In this paper, a discrete model is considered and a new algorithm Integral DFC (IDFC) is presented that has many preferences over similar algorithms, which are illustrated by simulation results and analytical discussions.     

Coupling between transmission‐line networks and homogeneous media: A semianalytical approach

Electromagnetic devices that incorporate volumetric networks of transmission lines with electrically small periodicity and cross‐sections are extensively used in various applications. Linear tapers can be employed in these configurations to achieve coupling between a homogeneous background medium and the volumetric transmission‐line structure. This is beneficial since various transmission‐line structures (homogenizable dense networks of transmission lines) are widely utilized to realize exotic electromagnetic properties commonly related to metamaterials. However, optimizing the dimensions of such multiparametric and electrically large devices could be computationally cumbersome. In this work, a simple semianalytic technique is proposed to reduce substantially the required simulation cost for an optimized design. The tapers are modeled semianalytically as consecutive coplanar components. On the other hand, the transmission‐line network is considered as a chain of identical unit cells, the response of which is numerically determined. The semianalytical result of the taper is combined with the numerical result of the unit cell by cascading the respective transfer matrices. The agreement of the obtained results with the corresponding full‐wave simulation data of the whole structure is very good. The decreased computational time required for the proposed approach is demonstrated through several numerical examples. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013     

A geometric approach for the analysis and computation of the intrinsic camera parameters

The authors of this paper adopted the projected characteristics of the absolute conic in terms of the Pascal's theorem to propose an entirely new camera calibration method based on purely geometric thoughts. The use of this theorem in the geometric algebra framework allows us to compute a projective invariant using the conics of only two images which expressed using brackets helps us to set enough equations to solve the calibration problem. The method requires restricted controlled camera movements. Our method is less sensitive to noise as the Kruppa's-equation-based methods. Experiments with simulated and real images confirm that the performance of the algorithm is reliable.     

A cellular topology-based approach to generating progressive solid models from feature-centric models

Progressive mesh representation and generation have become one of the most important issues in network-based computer graphics. However, current researches are mostly focused on triangular mesh models. On the other hand, solid models are widely used in industry and are applied to advanced applications such as product design and virtual assembly. Moreover, as the demand to share and transmit these solid models over the network is emerging, how to effectively stream the solid models has been considered as one of the major research issues. In this paper, we present a cellular topology-based approach to generating progressive solid models (PSM) from feature-based models. The proposed approach introduces a new scheme for storing and transmitting solid models over the network. The cellular topology (CT) approach makes it possible to effectively generate PSMs and to efficiently transmit the models over the network with compact model size. Thus, an arbitrary solid model SM designed by a set of design features is stored as a much coarser solid model SM⁰ together with a sequence of n detail records that indicate how to incrementally refine SM⁰ exactly back into the original solid model SM=SMⁿ.     

A new approach to the analysis of discrete event dynamic systems

We present a new, time domain approach to the study of discrete event dynamical systems (DEDS), typified by queueing networks and production systems. A general state-space representation is developed and perturbation analysis is carried out. Observation of a single sample realization of such a system can be used to predict behavior over other sample realizations, when some parameter is perturbed, without having to make additional observations. Conditions under which this is always possible are investigated and explicit results for some special cases are included.     

A new data mining approach to estimate causal effects of policy interventions

This paper presents a data driven approach that enables one to obtain a measure of comparability between-groups in the presence of observational data.The main idea lies in the use of the general framework of conditional multiple correspondences analysis as a tool for investigating the dependence relationship between a set of observable categorical covariates X and an assignment-to-treatment indicator variable T, in order to obtain a global measure of comparability between-groups according to their dependence structure. Then, we propose a strategy that enables one to find treatment groups, directly comparable with respect to pre-treatment characteristics, on which estimate local causal effects.