外文翻譯——專用服裝三維cad模型

1、<p><b>　　中文5952字</b></p><p>　　服裝設(shè)計中的計算機輔助方法</p><p>　　三維計算機輔助設(shè)計（ CAD ）技術(shù)正逐漸擴散到服裝的設(shè)計和制造應(yīng)用領(lǐng)域。目前，服裝行業(yè)普遍使用的二維CAD工具。預(yù)計，三維設(shè)計工具，將成為未來服裝行業(yè)中不斷發(fā)展的技術(shù)。服裝產(chǎn)品的設(shè)計的基本問題是合體性的問題以及相關(guān)的二維圖形生成的問題。最終目標是

2、設(shè)計和生產(chǎn)非常合體的個性化服裝，而三維方法是通過努力可以實現(xiàn)這一目標的最合理的辦法。三維方法包括幾個關(guān)鍵因素：其中包括參數(shù)化三維人體模型;三維服裝模擬;三維圖案設(shè)計，并3D/2D模型轉(zhuǎn)換。</p><p>　　做這個課題的目的是提供一個平臺，供研究人員回顧過去的技術(shù)發(fā)展，并為今后研究三維服裝設(shè)計方法找出可能的方向。這里選擇了題目相關(guān)的五篇論文，為服裝行業(yè)提供三維應(yīng)用程序發(fā)展的背景和技術(shù)。第一份文件是一個粗略的審查

3、織物仿真技術(shù)，該技術(shù)奠定了基礎(chǔ)的三維服裝設(shè)計。接下來的三篇論文詳細介紹了虛擬的環(huán)境中的三維服裝設(shè)計。最后一篇介紹了將三維服裝轉(zhuǎn)換為二維樣板的新技術(shù)。</p><p>　　第一篇論文是從Choi and Ko得到的，有關(guān)織物仿真研究問題。作為一項服裝設(shè)計和修改的基本技術(shù)，物理為基礎(chǔ)的織物仿真技術(shù)被用來產(chǎn)生織物運動的逼真效果。這篇論文介紹了織物仿真技術(shù)的三個方面：（1）服裝結(jié)構(gòu); （2）基于物理的模擬，和（3）碰撞檢

4、測和響應(yīng)。所面臨的技術(shù)挑戰(zhàn)，即創(chuàng)造更多的實際成果;實現(xiàn)更快的運行時間，制造/模擬更為復(fù)雜的服裝，是需要進一步研究的突出問題。</p><p>　　Volino等在第二篇論文中提出的，是一個框架，它符合服裝行業(yè)虛擬服裝設(shè)計和原型制作的需要。他們的做法集中在交互設(shè)計，模擬和可視化功能。作為先進的虛擬服裝仿真技術(shù)在過去十年中的總結(jié)，本文中介紹的框架集成了國家最先進的具有創(chuàng)新設(shè)計工具的物理模擬算法，提供高效率和高質(zhì)量的服

5、裝設(shè)計和原型制作程序。</p><p>　　第三篇論文介紹了一個綜合的環(huán)境，這使得設(shè)計師能夠通過分析服裝虛擬原型和仿真結(jié)果驗證他們的風格和設(shè)計方案，因此，物理原型的數(shù)量和作用會減少。和上一篇論文中提到的一樣，本文介紹的服裝虛擬原型的制作方法也是以物理為基礎(chǔ)的。他們能夠建立模型確定各向異性織物的經(jīng)緯向性能。牛頓動力學的限制適用于網(wǎng)格，以確定最后形成的合體服裝的形狀。本文中提到的通過應(yīng)用研究和對幾個男女性服裝項目中C

6、AD建模和物理模擬的分析，用來證明他們的系統(tǒng)功能。</p><p>　　在第四篇論文中，作者提出了一種同步三維服裝仿真結(jié)果更新算法，用于二維服裝紙樣設(shè)計的修改。用這種做法，對二維模式的修改無須每次重復(fù)整個三維服裝合體性仿真，樣板修改過程的效率被大幅度提升了。該算法的另一個優(yōu)勢是，二維服裝紙樣的網(wǎng)格拓撲結(jié)構(gòu)被保存，從而通過保持矩陣方程一致性簡化了數(shù)值格式。</p><p>　　為了把用戶制作

7、的三維服裝轉(zhuǎn)變成良好的二維板式，麥卡特尼等人在第五篇論文中介紹了一種方法。他們的算法，通過采用一個正交應(yīng)變模型來轉(zhuǎn)換鎖定在不可更新的能量函數(shù)中的應(yīng)變值。這些能源函數(shù)通過平坦約束三角網(wǎng)格被盡量減少。因為他們的應(yīng)變模型各向異性，其方法可以處理正交異性材料的平坦問題，這對服裝生產(chǎn)中三維模式轉(zhuǎn)變?yōu)槎S模式是非常重要的。他們的論文中也考慮了接縫插入問題。</p><p>　　在這里，我們要感謝對這些論文提供了寶貴的意見和見

8、解的審評者。這些論文表明，三維CAD技術(shù)在服裝設(shè)計中正在迅速成熟，將成為彌補學術(shù)研究和商業(yè)應(yīng)用在設(shè)計和制造服裝產(chǎn)品中差距的橋梁。盡管仍有物理模擬、碰撞檢測、 3D/2D轉(zhuǎn)換、高效的設(shè)計界面領(lǐng)域的技術(shù)需要改善，但是我們希望這一復(fù)雜的服裝設(shè)計任務(wù)可以通過CAD系統(tǒng)在不久的將來完成。</p><p>　　CAD methods in garment design</p><p>　　Three

9、dimensional Computer-Aided-Design (CAD) technology is gradually diffusing into the garment design and manufacturing applications. At present, the apparel industry widely uses two-dimensional CAD tools. It is anticipated

10、that three-dimensional design tools will be the next evolving technology for the apparel industry. The basic problems in apparel products design are the fitting problem and the related 2D-pattern generation problem. The

11、ultimate goal is to design and produce well-fitted per</p><p>　　The aim of this special issue is to provide a forum for researchers to review the past developments, and to identify possible directions for fu

12、ture research on 3D-approaches to garment design. The five papers selected for this special issue provide background and techniques for 3D-applications in the apparel industry. The first paper serves as a cursory review

13、of cloth simulation technology which lays the foundation of 3D-garment design. The following three papers show techniques for 3D-garment </p><p>　　The first paper is a review paper from Choi and Ko on resear

14、ch problems in cloth simulation. As a fundamental technique for the design and modification of apparel items, the physics-based cloth simulation technique is used to generate realistic cloth motion in real-time. Three te

15、chnical aspects of cloth simulation are reviewed in this paper: (1)garment construction; (2) physically based simulation, and(3) collision detection and response. The technical challenges, namely creating more realistic

16、</p><p>　　Presented in the second paper by Volino et al. is a framework which fits the needs of the apparel industry for virtual garment design and prototyping. Their approach concentrates on interactive des

17、ign, simulation and visualization features. As a result of the advances in virtual garment simulation technologies in the last decade, the framework presented in this paper integrates the state-of-the- art physical simul

18、ation algorithms with the innovative design tools to provide an efficient and quali</p><p>　　The third paper describes an integrated environment, which allows designers to validate their style and design opt

19、ions through the analysis of garment virtual prototypes and simulation results, so that the number and role of physical prototypes are reduced. In line with the previous paper, the garment virtual prototyping method pres

20、ented in this paper is also physics-based. They define the particle mesh associated with each fabric panel as a structured 2Dgrid whose coordinates aligned with the d</p><p>　　In the fourth paper, a synchron

21、ous 3D-garment simulation result updating algorithm is presented for 2D-garment pattern design modification. With this approach, the 3Dgarment fitting simulation is not required to repeat the entire simulation for every

22、2D-pattern modification, the efficiency of the pattern modification processing is greatly enhanced. Another advantage of the proposed algorithm is that the mesh topology of the 2D-garment pattern is preserved and thus si

23、mplifies the numerical scheme</p><p>　　In order to determine good fitting two-dimensional flattened patterns from user defined three-dimensional surface regions, an approach is presented by McCartneyet al. i

24、n the fifth paper. In their algorithm, an orthotropic strain model is adopted to convert the strain values locked in undevelopable regions to energy functions. These energy functions are minimized by flattening of constr

25、ained triangular mesh. Since their strain model is orthotropic, their method can handle the flattening problem o</p><p>　　Here, we would like to thank the reviewers who provided valuable comments and insight

26、s for all papers in this special issue. The papers in the special issue indicate that the 3D CAD approach in garment design is fast approach maturity that will bridge the gap between academic research and commercial appl

27、ication in the design and manufacturing of apparel products. There still remains improvement in the areas of physics-based simulation, collision detection, 3D/2D-conversion, and effective design </p><p>　　專用

28、服裝三維CAD模型</p><p><b>　　摘要：</b></p><p>　　雖然可用于服裝計算機輔助設(shè)計（ CAD ）系統(tǒng)的織物建模技術(shù)已取得相當進展，但是很少有人研究服裝CAD系統(tǒng)中指定服裝的方法。服裝的最后造型是通過省道、接縫、邊緣、襯墊和織物的局部延伸得到的。為了贏得信譽， CAD系統(tǒng)應(yīng)當可以通過簡單的界面來指定施工細節(jié)，并且有強大的功能處理復(fù)雜的服裝配

29、件?？尚械母拍罘椒ㄓ泻芏?。只要有準確懸垂算法，被選擇面料的服裝樣板就可以簡單地附著在模特兒上，實現(xiàn)服裝的可視化。如果有必要變化，用戶將修改二維樣板并重新運行可視化程序。另一種可能更富有成效的辦法是用先進的繪圖工具指定在3維環(huán)境下指定所需要的三維形狀。三維服裝會利用某種方式轉(zhuǎn)化為二維樣板并標明實現(xiàn)所需的最后形式的結(jié)構(gòu)細節(jié)。本文介紹的計算機輔助設(shè)計系統(tǒng)，正在努力實現(xiàn)上述過程。</p><p><b>　　1

30、 介紹</b></p><p>　　計算機輔助設(shè)計（ CAD ）現(xiàn)在是一個發(fā)展了很久的技術(shù)，目的是為工程應(yīng)用產(chǎn)生使用的設(shè)計方案。早期系統(tǒng)只是代替了繪圖板和繪圖工具。然而，現(xiàn)代CAD系統(tǒng)包含了許多分析工具，可以協(xié)助設(shè)計人員優(yōu)化設(shè)計或?qū)λ麄兊脑O(shè)計進行功能測試。此外，生產(chǎn)信息可以快速的從CAD設(shè)計中得到。計算機系統(tǒng)輔助服裝生產(chǎn)的技術(shù)直到今天一直在發(fā)展。服裝設(shè)計系統(tǒng)的研究集中在服裝的可視化，以及需要很快的產(chǎn)生

31、設(shè)計形象。這種系統(tǒng)已證明對制造服裝的企業(yè)非常有效，他們?yōu)橛写罅控浳锒冶仨殢念櫩吞幒藢嵲O(shè)計的大型零售機構(gòu)生產(chǎn)。CAD系統(tǒng)能夠迅速嘗試不同的顏色和紋理，這種功能在這種情況下是非常寶貴的。而且，這種系統(tǒng)能夠使用最新的打印機技術(shù)在原型上產(chǎn)生紡織品印花。此外，它的自動化程度很高，可在后續(xù)的生產(chǎn)過程中自動生成二維樣板和樣板的裁剪路徑。</p><p>　　仍然存在著三個計算機輔助設(shè)計很少涉及或沒有取得成功的領(lǐng)域。</

32、p><p>　　1 、電腦產(chǎn)生完整的三維服裝。</p><p>　　2 、自動生成二維樣板。</p><p>　　3 、精確敏感的模擬服裝面料的視覺感受并自動產(chǎn)生加工方法。 </p><p>　　這些領(lǐng)域發(fā)展緩慢導(dǎo)致了企業(yè)無法真正采用計算機集成方法設(shè)計和制造服裝。這篇論文的目的為服裝設(shè)計加工一體化過程提供可行的過程，重點介紹用戶界面和促進一體化的

33、核心技術(shù)。</p><p><b>　　2 發(fā)展現(xiàn)狀和局限</b></p><p>　　大多數(shù)生產(chǎn)大中批量的服裝制造公司的當前情況可以用圖1來描述。設(shè)計師根據(jù)以當前的流行趨勢產(chǎn)生的創(chuàng)作主題和目標市場設(shè)計產(chǎn)品。他們通常把設(shè)計畫在紙上，表達服裝的視覺效果。有時候設(shè)計稿上會附有加工時要用的面料樣本。需要指出的是，這種設(shè)計形式既不能被當做準確的服裝結(jié)構(gòu)，也不能被當做三維服裝的

34、二維展開圖。</p><p>　　圖1 普遍使用的服裝設(shè)計流程</p><p>　　因此，這意味著設(shè)計的溝通往往是非正式的，但對進行下一個生產(chǎn)階段足夠已經(jīng)詳細。這種情況的主要限制有兩個方面。 </p><p>　　1、制板師在制作二維樣板時對設(shè)計的解釋帶有主觀性。 </p><p>　　2、其次，通過評估階段的設(shè)計作品比例較低。</

35、p><p>　　這樣做結(jié)果不僅是拒絕了大量的樣品，更重要的是，浪費了時間和分散了精力。</p><p><b>　　3 計算機集成方法</b></p><p>　　這里提出的方法在圖2中表示了出來。框圖描述了計算機集成方法的核心要素。至今為止阻礙這樣一種綜合方法被接受的關(guān)鍵因素是：</p><p>　　●沒有一種有效的設(shè)計界

36、面，可以讓設(shè)計師方便的創(chuàng)造三維服裝； ● 沒有功能強大的把三維服裝變成二維樣板的軟件； ● 沒有準確的懸垂效果顯示技術(shù)。</p><p>　　為了順利的實現(xiàn)集成制造過程，以上三方面的技術(shù)都要有較大發(fā)展。下文將詳細介紹這些因素。</p><p><b>　　3.1 設(shè)計界面</b></p><p>　　

37、設(shè)計功能在服裝行業(yè)是一個創(chuàng)造性和藝術(shù)性的過程。任何提供給設(shè)計人員的計系統(tǒng)，不得抑制設(shè)計人員的藝術(shù)天賦。然而，設(shè)計者必須根據(jù)某些因素，例如成本和最終產(chǎn)品的功能，進行設(shè)計。增加在這些困難上的是服裝在穿著時的復(fù)雜形狀變化。設(shè)計師應(yīng)當通過設(shè)計界面向計算機表達什么形狀？本文提供的是一種全新的界面，可以生成三維服裝模型.這種模型在合體性要求高的地方必須能夠提供準確的表面描述，例如服裝接近基本模特的地方。這種表面描述必須能夠通過合適的人機交流界面和數(shù)

38、學技術(shù)實現(xiàn)。然而，讓設(shè)計人員描述布料懸垂的三維幾何形狀是不恰當?shù)?。CAD系統(tǒng)使用的技術(shù)（如各種形式的雙三次曲面）一定要能夠準確地表現(xiàn)織物懸垂的形狀，而不是讓設(shè)計師完成這些工作。其次，為了準確地預(yù)測或想象服裝的形狀，設(shè)計師非常了解面料的性質(zhì)。為了設(shè)計界面，在圖3 （a）中的表述可以被認為是初始服裝的風格形式，包含施工生產(chǎn)所必需的所有的細節(jié)。</p><p>　　圖2 建議使用的服裝設(shè)計方式</p>&

39、lt;p>　　由于設(shè)計師不能準確的描述服裝的每個細節(jié)，因此設(shè)計界面應(yīng)當提醒設(shè)計師界定其他細節(jié)。例如，如果選中了兩個毗鄰的小組件，那么系統(tǒng)應(yīng)當詢問它們應(yīng)當怎樣被連接。而且所以設(shè)計的面料屬性都要被確定。實際上，這一階段應(yīng)確定所有參數(shù)以便進行隨后的懸垂仿真。</p><p>　　在這個階段顯示的服裝三維表面有兩個重要的作用。首先，它提供了一個三維框架，在這個框架中，樣板的關(guān)系才能通過服裝組成被充分確定。此外它為懸

40、垂性模擬提供了一個很好的起點。因此，通常用來定義一個樣板的樣板節(jié)點將有三重作用：</p><p>　　作為初始的三維樣板的節(jié)點；</p><p>　　作為被轉(zhuǎn)化成的二維樣板的節(jié)點；</p><p>　　作為樣板懸垂性模擬的節(jié)點。</p><p><b>　　3.2 樣板展開</b></p><p>

41、;　　曾有人試圖做出生成服裝二維樣板的軟件。然而，這些努力幾乎沒有結(jié)果，因為二維樣板的生成需要一個完整的3D模型。此外，必須有一個智能化檢驗系統(tǒng)驗證樣板展開過程是否足夠精確。作者建議，服裝3D模型應(yīng)當被自動分成合體和懸垂兩部分。檢驗服裝屬于哪部分的標準是服裝與模特是否被抵消，以及服裝被迫抑制這種抵消的程度。</p><p>　　根據(jù)這一劃分，展開過程中合體部分和懸垂部分被分開對待.另一個重要因素是織物的材料特性。

42、由于面料通過梭織或針織結(jié)構(gòu)產(chǎn)生各向異性特性，這是個難以解決的問題。最后，二維扁平樣板不只是一個二維輪廓。需要有一個服裝如何從三維到二維映射的說明，這樣，需要考慮懸垂性時，反向進程可以實現(xiàn)。有人研究過，三維模型轉(zhuǎn)變?yōu)槎S的平坦算法。該算法能夠根據(jù)相關(guān)的曲率特性處理任意位置的接縫，包括省道和節(jié)點。</p><p><b>　　3.3 懸垂引擎</b></p><p>　　

43、此模塊應(yīng)能處理以下信息：</p><p>　　1、一個二維模式的幾何描述（包括足夠的內(nèi)部點以及與其他件的連接方式） 。</p><p>　　2、通過主要特點描述確定的織物種類。 </p><p>　　3、制約機制，如肩帶，拉鏈。 </p><p>　　4、人體模特表面曲面描述。 </p><p>　　5、表面紋理描述。

44、 </p><p>　　并且能夠準確預(yù)測織物的最后形狀。這是一個非常困難的要求大量計算的過程。有些人研究過其它方法。作者們所采取的模式必須能模擬服裝穿著時的各種耗能方式。這是研究拉伸剛度、抗彎剛度和屈曲行為得到的成果。</p><p>　　能夠用來準確描述材料特性的參數(shù)是：經(jīng)紗的方向拉伸應(yīng)變能量不變，Ksu；緯線方向拉伸應(yīng)變能量不變，Ksv；裁剪應(yīng)變能量不變，Kr；平面彎曲能量不變，Kb；

45、由織物單位質(zhì)量產(chǎn)生的潛在能量，Kg。</p><p>　　已經(jīng)出現(xiàn)了模型，可以根據(jù)面料性質(zhì)測量以上幾個參數(shù)。當3D系統(tǒng)中的某個節(jié)點的運動會減少總能量，問題就出現(xiàn)了。系統(tǒng)必須不斷的檢查，確保服裝樣板的節(jié)點與下面的模特兒不重合。這個問題可以通過在上述清單中另加入一個能量部件解決，它可以糾正與模特重合的樣板節(jié)點。此外，三維樣板有時會和自身重合。這些因素大大增加了計算的復(fù)雜性。該模型，體現(xiàn)出能源和幾何造型元素，稱為懸垂引

46、擎。表現(xiàn)的方法和關(guān)閉它的方法對形成樣板的最終形狀是很重要的。以往在這方面的工作突出了解決方案對計算要求嚴格的特點和在三維下解決方案的敏感性問題。</p><p><b>　　4 例子</b></p><p>　　圖3. a.三維板式設(shè)計 b.樣板網(wǎng)格化 c.樣板展平 d.懸垂效果和服裝紋理</p><p>　　表1.面料材料性能舉例</p

47、><p>　　假設(shè)一名設(shè)計師要設(shè)計貼體服裝的右前樣板。這需要理想的三維表面和為了達到貼體性而可選擇的省道位置。以下是兩個實例。由于本例的服裝不是可以完整的款式，所以需要固定某些點，防止啟動懸垂引擎時，服裝脫落。圖3（a）展現(xiàn)了在理想的三維表面生成的初始服裝樣板和固定點（分有A，B，C和D）。這個例子中沒有確定省道。在這一階段，表面由多邊形網(wǎng)格展現(xiàn)出來。網(wǎng)格的性質(zhì)顯示在圖3（b）中。 兩種面料類型A和B被考慮，它們的性

48、質(zhì)在表1中被定義。面料A在第一小組中。然后平坦進程開始，以獲取二維樣板。從三維到二維轉(zhuǎn)化的過程中，初始三維網(wǎng)格中的每一個節(jié)點被一對一的映射 （圖3 （ b ））。其結(jié)果在圖 3（c）中展示。最后，懸垂引擎被啟動。這個過程始于最初三維樣板圖3（a），盡量減少二維平坦面料轉(zhuǎn)化為目前的三維形狀時需要的總能量。最后懸垂后的三維形狀在圖3（d）中展示，樣板的A，B，C和D點被固定了。為了使視覺效果變得更好，織物紋理被渲染。這個功能因為懸垂引擎的2

49、D-3D映射被加強。</p><p>　　圖4. a.三維板式設(shè)計 b.樣板網(wǎng)格化 c.樣板展平 d.懸垂效果和服裝紋理</p><p>　　第二個例子在圖4（a）－（d）中被展示。在這個例子中，應(yīng)用了另一種布料（B型），而且一個省道在樣板的三維模式中被確定了出來（圖4（a））。為了保留整個省道的幾何形狀，原始的三維樣板被網(wǎng)格化（圖4（b））。這使得平展過程可以進行（圖4（c））。在展平過

50、程中，省道上的節(jié)點被雙重化，這樣省道才能形成。啟動懸垂引擎時，省道上的節(jié)點被固定在同樣的3D位置。最后的結(jié)果如圖4（d）所示。</p><p><b>　　5 結(jié)論</b></p><p>　　本文簡單介紹了服裝生產(chǎn)中的集成制造技術(shù)。設(shè)計界面、平展技術(shù)和懸垂性已被認為是阻礙技術(shù)發(fā)展的主要困難。例子中表現(xiàn)了服裝最終形狀怎樣受到面料性質(zhì)和省道等工藝技術(shù)的影響。為了使CAD

51、系統(tǒng)被服裝設(shè)計者和制造商實際使用，它必須提高模擬服裝真實表現(xiàn)的功能。</p><p>　　Dedicated 3DCAD for garment modelling</p><p><b>　　Abstract</b></p><p>　　While considerable progress has been made in fabric m

52、odelling techniques, which could be used in garment computer aided design(CAD) systems, less attention has been paid to the way in which garments might be specified in a CAD system. The final shape taken by a garment is

53、often achieved through the incorporation of darts, seams, edges, stiffening pads and local stretch of the fabric. In order to gain credibility,CAD systems should have to functionally handle the level of complexity normal

54、ly foun</p><p>　　Keywords: CAD; Garment design; Flattening; Draping</p><p>　　1. Introduction</p><p>　　Computer aided design (CAD) is now an established technique for generating prac

55、tical designs for most engineering applications. Early systems were simply a replacement for drafting boards and drawing tools. However, modern CAD systems incorporate many analysis tools to assist designers in optimisin

56、g designs or testing the functionality of their designs. In addition, manufacturing information can be generated efficiently fromCAD designs.The development of computer systems to aid the manufacture o</p><p&g

57、t;　　There remain three areas where computer assistance has met with little or no success.</p><p>　　1. The 3D specification of a complete garment.</p><p>　　2. The creation of 2D patterns.</p&g

58、t;<p>　　3. Accurate simulation of garment visualisation sensitive to fabric type and constructional detail.</p><p>　　The lack of development in these areas has resulted in the inability of companies t

59、o truly adopt a computer integrated approach to design and manufacture. The purpose of the work described here is to offer a possible configuration for such an integrated approach. This will highlight the impact as regar

60、ds the user interface and identify the core technologies required to promote this integration.</p><p>　　2. The present situation and limitations</p><p>　　The present situation for most garment m

61、anufacturing companies which produce medium to large batches can be described by Fig. 1. Designers originate designs based on their own creativity subject to current fashion trend sand the target market. Their design spe

62、cification is usually in the form of a paper drawing representing a visualisation of the garment.Sometimes attached to this drawing may be a small sample or swatch ofthe fabric fromwhich thegarment is to be made.Itis imp

63、ortanttonote that de</p><p>　　Consequently, this means of communicating designs tends to be informal but sufficiently detailed for the next manufacturing stage to proceed. The major limitations of this situa

64、tion are twofold.</p><p>　　The subjective nature of how the pattern technologist interprets the designs to produce the actual 2D patterns.</p><p>　　2. Secondly, the low acceptance rates that are

65、 achieved at the assessment stage.</p><p>　　This results in not only a large number of rejected samples but also,more importantly,lost time and diversion of effort.</p><p>　　3. Computer integrat

66、ed approach</p><p>　　The approach proposed here is presented in Fig. 2. This block diagram depicts the core elements required for an integrated approach. The key elements which have prevented such an integra

67、ted approach from being adopted to date are</p><p>　　●an effective design interface for designers to create 3D specifications of garments;</p><p>　　● a robust pattern flattening module;</p>

68、;<p>　　●an accurate drape engine.</p><p>　　For an integrated manufacturing approach to be successful, all three of these difficult elements must be adequately accomplished. These elements will now be

69、considered in</p><p>　　more detail.</p><p>　　3.1. Design interface</p><p>　　The design function in the garment industry is a creative and artistic process compared with the equivale

70、nt engineering function. So any design system, which is offered to designers, must not be perceived as restraining creative talent or constraining artistic flair. However, designers do operate within certain parameters i

71、n terms of cost and functionality of the final product. Superimposed on these difficulties is the complex and amorphous nature of the shape of the garment when worn. Precisely</p><p>　　mannequin. Such surfac

72、e descriptions must be capable of specification using existing mathematical techniques using a suitable interface. However, it would be inappropriate for a designer to describe the 3D geometry taken up by areas of the ga

73、rment where the fabric drapes. Current CAD systems would certainly be able to accurately represent these draped shapes using techniques such as the many forms of bicubic surfaces [1], but it would be unreasonable to expe

74、ct a designer to tediously specify suc</p><p>　　garment, the designer would have to have a very comprehensive knowledge of the fabric behaviour.For the purposes of the design interface, it is proposed that r

75、epresentations such as that shown in Fig. 3(a) would be acceptable for initial garment specification asa stylised formwhich would be capable of incorporating all of the constructional detail necessary for manufacture.<

76、;/p><p>　　While notbeingan attempt toaccurately simulatethe 3D appearance of the garment at this point, the design interface should embody functionality to implicitly define all other aspects of the garment spe

77、cification. For instance, if two abutting panel pieces are defined then there should follow a requirement to nominate how these panels are to be joined.Also fabric types should be defined for all panels. In effect, this

78、stage should define all of the parameters for a subsequent drape simulation to p</p><p>　　The 3D surface representation of the garment displayed at this stage has two important roles. Firstly, it provides a

79、3Dframework within which panel relationships can be fully defined in terms of the garment composition. Also it provides a reasonable starting point for drape simulations.Thus,panel nodes which are used to define a panel

80、will have a triple representation as follows.</p><p>　　1. As a node in the initial 3D stylised panel.</p><p>　　2. As a node on the 2D flattening of the panel.</p><p>　　3. As a node

81、in the drape simulation of the panel.</p><p>　　3.2. Pattern flattening</p><p>　　Some attempts have been made to provide software to generate 2D patterns for garments [2,3]. However, these have m

82、et with limited success because of the prerequisite that a full 3D specification must previously exist in order for a 2D pattern to be derived.Also,there has to be an intelligent examination of the garment specification

83、to establish how critical the pattern flattening process should be in conforming to the original 3D surface. The authors propose that the garment specification should</p><p>　　offset with respect to underlyi

84、ng mannequin and the degree to which the garment is forced to be constrained to this offset.</p><p>　　Depending on this partitioning, the flattening process would flatten fitted areas differently from draped

85、 areas. Another influential factor would be the material characteristics of the fabric involved. This is made more difficult by the anisotropic nature of most fabrics due to their woven or knitted construction. Finally,

86、it is important that 2D flattening specifications do not simply consist of a 2D outline.There needs to be a full interior description of how the garment is mapped from 3D to 2</p><p>　　3.3. Drape engine</

87、p><p>　　This module should be capable of taking the following information: </p><p>　　●A geometric description of a 2D pattern (including sufficient interior points and connectivity relationships wi

88、th other pattern pieces).</p><p>　　● Fabric type as described by key material characteristics.</p><p>　　●Constraining mechanisms, e.g. straps, zips. </p><p>　　●Underlying mannequin

89、surface description. </p><p>　　●Surface texture description. </p><p>　　and produce an accurate prediction of the final shape of the fabric. This is avery difficult and computationally demanding

90、process.Various approaches are possible as summarised elsewhere [5]. The one taken by the authors has been to model the various energy dissipation modes which exist when a garment drapes. These result from tensile stiffn

91、ess, bending stiffness and buckling behaviour.</p><p>　　The precise variables used to represent material behaviour are tensile strain energy constant,inthewarpdirection,Ksu;tensile strain energy constant in

92、the weft direction,Ksv;shear strain energy constant, Kr; out-of-plane bending energy constant, Kb; potential energy resulting from fabric mass,Kg.</p><p>　　The model developed [6], evaluates the total energy

93、 derived from these sources and obviously depends on the particular fabric used. When individual nodes are then moved in 3D to reduce the total energy, major problems can arise. Checks must be continuously made to ensure

94、 that nodes on the garment panel do not intersect with the underlying surface of the mannequin. This can be handled by incorporating an additional energy component to the list above, which severely penalises nodal moveme

95、nt if int</p><p><b>　　Example</b></p><p>　　Suppose that a designer is required to design the right front panel of a fitted garment.This will require the idealised specification of th

96、e 3D surface for the panel and the optional location of where a dart can be sited to improve the fit of the panel. Two possible examples are presented. Since the examples are not part of a self-sustaining garment, then f

97、ixture points will have to be specified or the panels will</p><p>　　simply slip off the mannequin when submitted to the drape engine. Fig. 3(a) illustrates the initial representation of the first garment pan

98、el indicating the idealised 3D shape, the positions of fixation to the underlying body (points A, B, Cand D). No dart is specified for this example. At this stage,the surface is represented by a polygonal mesh. The preci

99、se nature of the mesh is shown in Fig.3(b).Two fabric types A and B, will be considered for the two examples and the material characteristic </p><p>　　provided in Fig. 3(c). Finally, the drape engine is appl

100、ied.It starts with the initial 3D shape of Fig. 3(a) and seeks to minimise the total energy required to distort the 2D flattening to assume the current 3D shape. The final 3D draped shape is provided in Fig. 3(d) which t

101、akes into account the fixing positions for the panel at points A, B, C and D. For added visual realism, texture rendering is applied. This is enhanced because of the authentic 2D–3D mapping which is provided by the drape