Geometrical algorithms of clothes element synthesis

Elements of clothes synthesis is an evolvent (patterns, which are the basis for garment making) creation. Now the problem computer-aided design systems for garment creation is enough actual, that is visible from the analysis of development and a place in the software market of similar development. Similar CADs will be demanded not only by the enterprises of the textile industry, but also by founders of three-dimensional characters in such systems, as 3D-Max, separate modules of which allow to create clothes to the character with the basis patterns.

Many industries face problems of construction of curvilinear surfaces and their evolvents. In sewing branch settlement-graphic ways of evolvent construction on a small number of figure surface measurements of the person are most widespread.

However, high accuracy of evolvent cpeation cannot be reached by settlement-graphic methods which base on anthropological researches. Engineering and geometrical methods - are more universal.

Existing programs for designing elements of clothes use a number of settlement-graphic and engineering methods. In some cases the used technique is not disclosed, remaining a know-how of the enterprise-developer. Among analogues it is possible to list such: system PatternsCAD from PatternsCAD Software, system of construction of patterns of developers "East-solo", CAD for clothing industry Comtense, system STAPRIM developed on faculty of designing and technology of garments of the St.Petersburg state university of technology and design, CAD Grazia, the program of creation of patterns Patternmaker, CAD from Gerber Technology, Novocut, Lectra, Investronica.

Analogues can be divided on two categories: appendices for generation of patterns on a typical figure and high-grade CAD for designing clothes.

The Example of systems of the first category are system PatternsCAD from PatternsCAD Software, system of construction of patterns of developers "East-solo". Their basic lacks are:

• Absence of an clothes modelling opportunity;
• Absence of the received product three-dimensional image;
• Using some standard patterns generation algorithms, that only simplifies work of the tailor, but does not switch pattern synthesis on qualitatively new level.

The second category software product example (high-grade CAD) - system STAPRIM:

• Priority of the spatial form of clothes above its involute, i.e. primacy of the task of the three-dimensional form of clothes and secondariness of construction of its involute on a plane;
• The control of appearance of a product over an opportunity of the three-dimensional image of a product in different foreshortenings;
• Opportunity to build a product on a typical figure and on a figure with deviations.

More detailed analysis of analogues is inconvenient.

During research the set of publications on subjects textile industry and on subjects computer schedules and to modelling of clothes has been analysed.

Article «Clothing Manipulation» of the the Japanese and American authors describes technics of interaction of a fabric and the three-dimensional character on an example of their own development - the three-dimensional editor. The emphasis is done on program modelling of behaviour of a fabric, instead of on creation of involute.

An Article “The Method of construction involute bilinear surfaces with use of power functions” is basic since represents results of research of an opportunity of expansion of surfaces, such which have nonzero gauss curvature - i.e. cannot be involute with absolute accuracy. As the figure of the person is not a involuted surface the question on creation of involute with an admissible error is very important. Thus we consider physical properties of fabrics, for work with which we make involute, and, owing to this, we receive good results

Article «Reception of involute of volumetric details of garments by means of a graphic method» - the description of creation of involute by means of Chebushov net. The way consists in drawing on the isolated involute of a three-dimensional surface received by a method of a triangulation.

The Most interesting article «A body and garment creation method for an Internet based virtual fitting room» - the description of new methodology of creation of realistic three-dimensional model of the clothes intended for demonstration (advertising) to users of details of clothes which is already on shelfs of shops. The three-dimensional image of clothes is created on bidimentional patterns of represented (advertised) clothes and corresponding parameters of a body of the client.

Thus, we see, that the scientific community is interested by the given subjects, development are conducted actively and take root into manufacture that speaks about a demand and a urgency of the project.

As careful research the Internet-space has shown, in problems of synthesis of elements of clothes are engaged many institutes of the world. In space of the CIS it is possible to allocate such HIGH SCHOOLS and their development: о выделить такие ВУЗы и их разработки:

• Development of faculty of designing and technology of garments of the St.Petersburg state university of technology and design;
• Московский Государственный Университет Дизайна и Технологии (МГУДТ) – один из первых в России вузов по подготовке специалистов для лёгкой промышленности;
• Novosibirsk state technical university;
• The faculty engineering and computer schedules of the Vinnitsa national technical university, one of which achievements is system " GEOM ". System GEOM includes a complex of the programs anyhow connected with bases of geometrical modelling and computer schedules.

The theme of clothes elements synthesis is enough actual, that leads to a problem коммерцирования researches. Results of global researches on given theme are presented by set of practical results - programs-analogues of high quality.

Let's list such institutes:

• Worcester Polytechnic Institute, USA;
• University of Geneva, Switzerland;
• University of Tokyo, Japan;
• Brown University, USA.

The Technique of designing consists of the information on a figure of the person and a finished article, methods of processing of the received information (the formula of transformation) and ways of geometrical construction of a design of clothes. It is important, that at designing features of a constitution and technological processing are considered.

Existing methods of designing divided on approached and engineering ones. To the approached methods of construction concern: mould, settlement-graphic, geometrical. To engineering methods carry: methods of a triangulation, secants of planes, constructive strips and zones and geodetic lines.

In any case, steps of the researcher are:

1. Studying of clothes elements synthesis methods;
2. The analysis of efficiency of application of investigated methods;
3. The review of the program systems-analogues using geometrical methods;
4. The analysis of alternative ways of the decision.

It is a lot of variations of a method. Their common features consist in the following:

Basis of a method is involute of a surface of a figure or a dummy. The developed surface is broken into large enough triangles conditionally accepted for developed.

the Key moment - a way of splitting figures on conditionally developed triangles. First , it is impossible to speak that the surface of a body of the person can be involuted. We receive the first unacceptable result. There is a question on an admissible degree of approach{approximation} of involute to initial model.

Secondly , breaking a surface on triangles, we should consider the aesthetic side and problems of technological processing of a product. Easier speaking, we cannot give completely the scheme of expansion to algorithm on which input the model of a figure of the person and an error gets - it to us unwrap a surface on slices which we cannot combine. We should set the lines limiting each element of involute. This problem is solved by means of attraction of experts of the textile industry and a possibility of intervention of the user at designing (by means of задавания the user of borders of involute).

After surface involute construction, we build involute of the basic details. At this stage features of clothes, вносимые are considered by the designer.

Construction of conditional involutes is action with the error. To optimize the program, we shall aspire to leave from uncountable derivatives, replacing differential equations systems by linear equations systems, that again will give a result with a margin error.

At this stage it is necessary to reflect seriously, and whether there is a sense to use bulky variants of a method when with the same error we can probably receive qualitative elements of clothes, using settlement-graphic methods which are tested many years and are used in the textile industry? Certainly, the settlement-graphic methods used in the industry, are focused on a minimum of calculations and on a typical figure of the person, that speaks against them. However, they are a subject to improvement that will lead to complication of calculations and geometrical constructions which will be carried out nevertheless more quickly the decision of differential equations systems, but will not be accessible without application of computer facilities.

The Requirement in research of mentioned algorithms has arisen with idea of development of the software product corresponding such requirements:

• Maintenance of clothes designing automation;
• Possibility of application of the labour-consuming techniques accessible exclusively at program of clothes elements synthesis.

The software product developed by the author at the given stage is system of synthesis of elements of clothes and designs patterns and is based on settlement-graphic methods. It is possible to carry refusal of use of methods to its advantages manufactures of products. It means, that the program designs involute of a product not on the is conditional-typical person, and is direct on the customer, considering features of its figure.

The Further development of the given theme assumes detailed research of methods of three-dimensional designing of clothes and engineering methods of construction of involute, and also maintenance of convertibility of the received results (patterns) in the most widespread formats graphic САПР and modern САПР for designing clothes

Designing of clothes by CAD allows the developer to reduce time for creation of a product pattern, to improve conformity of a pattern to parameters of the person (and consequently to improve quality of a finished product), to reduce time of dialogue with the client.

The examined analogues of developed software product allow to speak about their merits and demerits, about a competition and interchangeability, tendencies. As to tendencies on the foreground there is a decision to prefer the spatial form of an element of clothes, instead of a flat pattern at designing.

The Analysis of publications on subject has shown geometrical synthesis of elements, that basic researches of this theme are conducted even from work Chebushov where the analytical decision of a problem of "surface clothing" proves. Besides from modern publications and the researches leaded in various world institutes, it is visible, that the subjects is actual and is actively developed.

It is necessary to notice also, that research works of the Europe are more aimed at creation of analytical base while the USA and Japan give weight of practical decisions of a problem.

1. Reception of involute of volumetric details of garments by means of Valentina Kurysheva's graphic method - the Moscow state university of design and technology, Moscow, Russia..
2. Official site Gerber Technology Solutions, http://www.gerbertechnology.com.ua
3. Official site Comtense, http://comtense.ru/idx.htm.
4. Оfficial site PatternsCAD Software, http://www.patternscad.best-host.ru.
5. Clothing Manipulation. Takeo Igarashi Computer Science Department, University of Tokyo 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033 Japan, John F. Hughes Computer Science Department, Brown University Providence, RI 02912, USA
6. Research problems in clothing simulation, Kwang-Jin Choi, Hyeong-Seok Ko
7. Tutorial on Cloth Modelling" by Karthikeyan, Ranganathan
8. V.D.Frolovsky. A method of power functions of construction involute surfaces. The Siberian magazine of industrial mathematics. January-June 2000, Volume III, 1 (5).
9. A body and garment creation method for an Internet based virtual fitting room. Dimitris Protopsaltou,Christiane Luible, Marlene Arevalo, Nadia Magnenat-Thalmann MIRALab CUI, University of Geneva, CH-1211, Switzerland