Igor' Vitovtov

Bio: Igor' Vitovtov is an academic researcher. The author has contributed to research in topics: Tangent & Curvature. The author has co-authored 2 publications.

Approximation of Physical Spline with Large Deflections

Abstract: Physical spline is a resilient element whose cross-sectional dimensions are very small compared to its axis’s length and radius of curvature. Such a resilient element, passing through given points, acquires a "nature-like" form, having a minimum energy of internal stresses, and, as a consequence, a minimum of average curvature. For example, a flexible metal ruler, previously used to construct smooth curves passing through given coplanar points, can be considered as a physical spline. The theoretical search for the equation of physical spline’s axis is a complex mathematical problem with no elementary solution. However, the form of a physical spline passing through given points can be obtained experimentally without much difficulty. In this paper polynomial and parametric methods for approximation of experimentally produced physical spline with large deflections are considered. As known, in the case of small deflections it is possible to obtain a good approximation to a real elastic line by a set of cubic polynomials ("cubic spline"). But as deflections increase, the polynomial model begins to differ markedly from the experimental physical spline, that limits the application of polynomial approximation. High precision approximation of an elastic line with large deflections is achieved by using a parameterized description based on Ferguson or Bezier curves. At the same time, not only the basic points, but also the tangents to the elastic line of the real physical spline should be given as boundary conditions. In such a case it has been shown that standard cubic Bezier curves have a significant computational advantage over Ferguson ones. Examples for modelling of physical splines with free and clamped ends have been considered. For a free spline an error of parametric approximation is equal to 0.4 %. For a spline with clamped ends an error of less than 1.5 % has been obtained. The calculations have been performed with SMath Studio computer graphics system.

Nature-like curve modeling

Abstract: A physical spline is called an elastic rod the cross- section dimensions of which are rather small as compared with the length and radius of its axis curvature. Such a rod when passing through specified points obtains in natural way a nature-like shape characterized with minimum energy of inner stresses and minimum mean curvature. A search for the equation of elastic line is a difficult mathematical problem having no elementary solution. The work purpose: the development of the experimental-rated procedure for modeling a nature-like elastic curve passing through complanar points specified in advance. The investigation methods: methods of piece-cubic interpolation based on the application of polynomial splines and compound curves specified by parametric equations. In the paper there are considered polynomial and parametric methods of the geometric modeling of the physical spline passing through the points specified in advance. The elastic line of the physical spline is obtained experimentally. The investigation results: it is shown that unlike a polynomial model a parametrized model on the basis of Fergusson curve gives high accuracy of approximation if in basic points there are specified tangents to the elastic line of the physical spline with large deflections. Novelty: there is offered a simplified method for the computation of factors of an approximating spline allowing the substitution of the 2n system of nonlinear equations (smoothness conditions) by the successive solution of n systems of two equations. Conclusions: for the modeling of nature-like curves with large deflections there is offered the application of Fergusson cubic spline passing through specified points and touching the specified straight lines in these points. The error of the modeling of the natural elastic line with free ends at n=5 does not exceed 0.4%.

Functional-Voxel Modelling of Bezie Curves

Abstract: The problem of this research is the impossibility of applying parametric functions in theoretical-multiple modeling, that significantly narrows the range of problems solved by analytical models and methods of computational geometry. To expand the possibilities of R-functional modeling application in the field of computer-aided design systems, it is proposed to solve the problem of finding an appropriate representation of parametric curves using functional-voxel computer models. The method of functional-voxel modeling is considered as a computer graphic representation of analytical functions’ areas on the computer. The basic principles and examples of combining R-functional and functional-voxel methods with obtaining R-voxel modeling have been presented. In this case, R-functional operations have been implemented on functional-voxel models by means of functional-voxel arithmetic. Based on the described approach to modeling of theoretical-multiple operations for the function area represented by graphical M-images, two approaches to construction a functional-voxel model of the Bezier curve have been proposed. The first one is based on the sequential construction of the curve’s interior by intersection a positive area of half-planes, which enumeration is performed by De Castiljo algorithm. This approach is limited by the convexity of the curve’s reference polygon. This problem’s solution has been considered. The second approach is based on the application of a two-dimensional function for local zeroing (FLOZ), i.e., a nil segment on the positive area of function values. By consecutive unification of such segments it is proposed to construct the required parametrically given curve. Some features related to operation and realization of the proposed approaches have been described and illustrated in detail. The advantages and disadvantages of described approaches have been highlighted. Assumptions about applicability of proposed algorithms for Bezier curve functional-voxel modeling in solving of various geometric modeling problems have been made.

Content of the “Geometric Modeling” Course for the “Mathematics and Computer Science” Training Program

Abstract: In this paper has been considered the main content and distinctive features of the “Geometric Modeling” training course for the “Mathematics and Computer Science” training program 02.03.01 (“Mathematical and Computer Modeling” specialization). The goal of the “Geometric Modeling” course study is the assimilation of mathematical methods for construction of geometric objects with complex curved shapes, and techniques for their computer visualization by using polygons of curves and surfaces. Methods for construction of structures’ curved shapes using spline representations, as well as techniques for construction of surfaces and volumetric geometries using motion operations and basic logical operations on geometric objects are considered. The spline representations include linear and bilinear splines, Hermite cubic splines and Hermite surfaces, natural cubic and bicubic interpolation splines, Bezier curves and surfaces, rational Bezier splines, B-splines and B-spline surfaces, NURBS-curves and NURBS-surfaces, transfinite interpolation methods, and splines of surfaces with triangular form. Logical operations for intersection of two spline curves, and intersection of two parametric surfaces are considered. The principles of scientific visualization and computer animation are considered in this course as well. Some examples for visualization of initial data and results of curves and surfaces construction in two- and three-dimensional spaces through the software shell developed by authors and used by students while doing tests have been demonstrated. The software shell has a web interface with the WebGL library graphic support. Tasks for four practical studies in a computer classroom, as well as several variations of homework are represented. The problems occurring in preparation materials for some course sections are discussed, as well as the practical importance of acquired knowledge for the further progress of students. The paper may be interesting for teachers of “Geometric Modeling” and “Computer Graphics” courses aimed to students with a specialization in mathematics and information, as well as to those who independently develop software interfaces for algorithms of geometric modeling.

All-Russian Scientific and Methodological Conference «Problems of Engineering Geometry» and the Seminar «Geometry and Graphics» 2021

Abstract: The article is devoted to the annual All-Russian scientific and methodological conference "Problems of Engineering Geometry" and the annual All-Russian scientific and methodological seminar "Geometry and Graphics" in 2021. Statistical information about the conference and seminar is provided: the number of participants, universities, the number of cities and countries in which universities are located -participants. Using the expression proposed earlier, the activity of participation of the departments of graphic disciplines in the conference "Problems of Engineering Geometry" and the seminar "Geometry and Graphics", held in 2021, was determined. The comparison of the number of participants and reports of the conference and seminar in 2021 with the number of participants and reports is given and analyzed International Internet conferences "Quality of graphic training" at the Perm National Research Polytechnic University. The results of the All-Russian Seminars "Geometry and Graphics" and the All-Russian Conferences "Problems of Engineering Geometry" of the last two years are compared with each other. In order to compare conferences and seminars quantitatively, not qualitatively, a relationship has been proposed. The content of the reports of the participants of the conference and the seminar is briefly considered. Conclusions are drawn: 1) in 2021, in terms of the success of the seminar "Geometry and Graphics" and the conference "Problems of Engineering Geometry", we managed to move forward - the success rate increased; 2) judging by the number of reports, scientific work on the profile of the department is carried out in a small number of departments. This is due to shortcomings in the staffing of departments of graphic disciplines by teachers. One of them is a lack of understanding that the winners or participants of All-Russian and regional Olympiads who have undergone appropriate training should work as teachers.

Geometric modeling of the contour arcs passing through the predefined points

Abstract: Multidimensional interpolation is an important scientific task in demand of various science fields and technology. The geometrical theory of multidimensional interpolation has been further developed in terms of extending the shaping tools of geometrical modeling at the expense of the contour arcs passing through the predefined points. The proposed method is based on modification of Bezier’s curve with preservation of tangents in its initial and/or final points. Then the Bezier curve retains its geometrical properties of the arc, but additionally has the possibility to pass through several points set in advance. Examples are given of modifying a 5th-order Bezier curve arc into a curve arc passing through four predefined points and a 3rd-order Bezier curve arc passing through three predefined points and having a tangent in the initial point, which is proposed to be used as the onion dome surface forming arc. Such a method helps to reduce the piecewise character of composite curves when building curves. The introduction of such research results into computeraided design and solid-state modeling (CAD/CAM) systems will allow to expand their toolbox in terms of shaping surfaces and solids of technical shapes of various purposes.