SEOUL NATIONAL UNIVERSITY

Transcription

1 Fashion Technology 3. Pattern Design Sungmin Kim SEOUL NATIONAL UNIVERSITY Design Process Overview Concept Design Fabric Design Scalable vector graphics Feature-based design Weave CAD 2.5D Mapping Design Process Pattern Design 2D Parametric design 3D pattern design Garment Design Body modeling 3D draping simulation 2

2 Pattern Design What is Pattern? Definition 3D garment should be developed into 2D pieces for production These 2D pieces are called 'patterns' More patterns are used for complex shaped garment Pattern Generation Processes Basic pattern generation Grading for size variation Preparation of auxiliary patterns Addition of ease for sewing 3 Pattern Design Pattern Design Methods Simple Measurement Method Use a few sizes based on the longest line Bust girth for upper garment Hip girth for lower garment Suitable for beginners Not experienced in body measurement Needs additional fitting process Complex Measurement Method Use many sizes for detailed geometry Suitable for individually fit garment Eclectic Method Compromised method of two methods 4

3 Pattern Design Problems Paper Patterns Most companies use paper patterns Experienced pattern designers are required Dependent on the skill of digitizer 5 Pattern Design Problems Difficult Grading Relies on experience and needs additional fitting Cut and spread method Point shifting method 6

4 Pattern Design Solution Formulation of Pattern Design Method Convert pattern design formula into computerized method Beginners can generate various patterns Grading and fitting can be eliminated or reduced Three-dimensional Pattern Design Generate patterns directly from three-dimensional body scan data No need for pattern design formula Intuitive garment design 7 Pattern Design Systems Importance Changes in the market environment Diversification of consumer needs Intensification of price competition Intensification of international competition Shortening of product life cycle Changes in the Design Environment Intensive competition for new product development Increasing need for low-cost high-quality design Shortened design lead time Increased design workload due to diversified product specifications 8

5 Pattern Design Systems Importance Changes in the manufacturing environment Diversified and small quantity production system Increased automation in manufacturing processes Maximized utilization of facilities and equipment Changes in the human environment Increased labor cost for higher education Lack of skilled workforce Lack of young labor Reduced work time 9 Pattern Design Systems Input Device Pattern Scanner Garment Digitizer 10

6 Pattern Design Systems Output Device Plotter Cutting Plotter High ply flatbed type cutting machine 11 Pattern Design Systems Software Pattern making Paper patterns are digitized into computer Patterns are manipulated by various editing functions either automatically or interactively Generation of master and engineering patterns 12

7 Pattern Design Systems Software Grading Parametric design based method Pattern shifting method Cut and spread method 13 Systems Software Marking Pattern Design Arrangement of graded patterns on a given size of fabric with minimum loss Various constraints should be resolved including fabric length, warp direction, or figures Automatic, interactive, example-based methods 14

8 Pattern Design Systems Commercial Systems 15 Basics Data Structure Garment Pattern Pattern Pattern... Point Notch Drill Hole Line Cutline Grading Info. Segment Segment Segment Sewing Line Internal Lines Meta Information (name, type, grain, etc.) Reference to Point Reference to Point Reference to Point... 16

9 Basics Definition of Pattern Geometry Cut Line Curve Control Point Sewing Line Grain Corner Point Notch Internal Line Drill Hole Pattern 17 Basics Segment Basic element of geometry definition Curve Control Point Corner Point Corner Point Requirements for a segment Must go through the given points Length can be calculated Arbitrary position can be determined on it 18

10 Basics Bezier Curve History Piere Bezier (Renault) reported in 1962 Based on the Bernstein polynomial which had been known for long time Advantage Simple calculation Disadvantage Vibration can occur with too many hull points Movement of any point can affect the overall shape 19 Basics Spline Curve Feature Piecewise representation with polynomial equations Curve does not go through control points just like a Bezier curve Advantage Movement of a point affects only the local shape of the curve Disadvantage Incapable of the representation of quadratic curves» Circle, ellipse, parabola, etc. 20

11 Basics NURBS (Non-Uniform Rational B-Spline) Curve Advantage Capable of any kinds of 2D and 3D curves and surfaces Represent all the elements in a drawing with unified data structure Simple and precise control Disadvantage Complex calculation 21 Basics Pattern Manipulation Example Delete point Internal line definition Division Line reshaping 22

12 System Parametric Design Definition Conversion of pattern design formula into computerized method Body measurement data are used as parameters Advantages Grading process can be eliminated Additional fitting can be reduced Disadvantages Difficult to convert so many existing pattern design formula Types Program based Script based Interactive 23 Parametric Pattern Design Program Based Design Method Pattern design formula is converted using a programming language (hard-coding) Advantages Any kind of complex formula can be converted Disadvantages Different software should be made for each pattern Software programming experts are needed 24

13 Parametric Pattern Design Script Based Design Method Define the geometry of a pattern (point, line, etc.) using a dedicated script language Advantages Complex patterns can be defined relatively simpler than the programming method Reusable patterns can be managed as subroutines Easy to use Disadvantages Difficult to see the intermediate shape of a pattern Command Syntax Description Point Point, Name, X, Y Define a point (X,Y) Move Move, Name, Original, dx, dy Define a new point by moving the original point by (dx, dy) Divide Divide, Point 1, Point 2, m, n Define a new point by dividing Point 1 and 2 by m:n Length Length, L, Point 1, Point 2 Assign the length between Point 1 and 2 to L Line Line, Name, Point 1, Point 2, Point 3,... Define a line using point list Pattern Pattern, Name, Line 1, Line 2,... Define a pattern using line list Variable Variable, Name, Equation Assign the evaluated value of equation to a variable Include Include, Script Include another script 25 Parametric Pattern Design Script Based Design 26

14 Parametric Pattern Design Interactive Design Method Use interactive user interfaces to define a pattern Advantages Intermediate shape of a pattern can be monitored intuitively Simpler than the script based method Disadvantages Patterns with complex geometry cannot be designed easily 27 Parametric Pattern Design Interactive Design 28

15 Camera based Pattern Digitizer Method Use a camera to digitize garment patterns instead of the scanners Advantages Less expensive and faster than conventional scanner systems Disadvantages Precision can be affected by lighting condition or image analysis process 29 Camera based Pattern Digitizer Principles of Camera Calibration The image is distorted by the lens 30

16 Camera based Pattern Digitizer Principles of Camera Calibration Method to match the world coordinate with the camera coordinate y Camera x Checkerboard (World Coordinate System) Grid Reconstruction 31 Camera based Pattern Digitizer Isoparametric mapping (x1,y1) (x2,y2) (x3,y3) 0.3 (x4,y4) 32

17 Camera based Pattern Digitizer Image Analysis Definition The extraction of meaningful information from images, mainly from digital images Techniques Enhancement Segmentation Tracing Measurement Applications Medicine : Detecting cancer in a mammography scan Astronomy : Calculating the size of a planet Material Science : Determining if a metal weld has cracks Robotics : Avoid steering into an obstacle OCR : Automatic license plate detection And so on Camera based Pattern Digitizer Techniques for Garment Pattern Recognition Binarization Color image (RGB) into gray scale image : Red + Green + Blue Gray = 3 Gray scale image into binary into : 1 Value = 0 (Gray < Threshold) (Gray > Threshold) Threshold value greatly affects the final product 34

18 Camera based Pattern Digitizer Techniques for Garment Pattern Recognition Contour Extraction Find the contour of object obtained by thresholding Thinning Convert the contour into 1-pixel wide line Tracing Find a closed loop (pattern outline) using counterclockwise tracing 4-connectivity 8-connectivity Thresholded Object Border pixels with 8-connectivity Thinned and traced contour 35 Camera based Pattern Digitizer Image Analysis 36

19 Camera based Pattern Digitizer Image Analysis Saved as DXF-AAMA for compatibility Drawing exchange Format American Apparel Manufacturers Association 37 Pattern Marking System Marker Making Definition Placement of numerous patterns on a fabric with minimum loss One of the most important processes for cost savings Problems in manual method Number of possible markers dramatically increases as the number of patterns Objective evaluation of marker efficiency is very difficult Many constraints cannot be resolved easily such as fabric width, defect, etc. 38

20 Pattern Marking System Principles of Marker Making Rasterization of Fabric and Patterns All Pattern Orders (n!) All Patterns Rasterization of Pattern Place Pattern Evaluate Efficiency Find Best Marker Placement of a pattern on rasterized fabric 39 Pattern Marking System Principles of Marker Making Pattern placement rule The first pattern is located at bottom left corner Optimum location is searched from the second pattern A total of n! placement orders exist Worse Bounding Rectangle First pattern Better Area of placed patterns Efficiency = Area of Bounding Rectangle 40

21 Pattern Marking System Principles of Marker Making Constraints Patterns may need to be marked in groups according to the fabric type The length of fabric that can be handled in a batch may be limited Collar/Cuffs/Yoke Bodice Sleeve Interlining 41 Pattern Marking System Principles of Marker Making Constraints Marking on a complex shaped domain such as leather or fabric with defects 42