Sungmin Kim

SEOUL NATIONAL UNIVERSITY

Fashion Technology3. Pattern Design

Garment Design

• Body modeling• 3D draping simulation

Pattern Design

• 2D Parametric design• 3D pattern design

Fabric Design

• Weave CAD• 2.5D Mapping

Flat Sketch

• Scalable vector graphics• Feature-based design

Design Process

Overview

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DesignProcess

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

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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

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Pattern Design

Problems Paper Patterns

Most companies use paper patterns

Experienced pattern designers are required

Dependent on the skill of digitizer

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Pattern Design

Problems Difficult Grading

Relies on experience and needs additional fitting

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Cut and spread method Point shifting method

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

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Pattern Design

Solution Three-dimensional Pattern Design

Generate patterns directly from three-dimensional body scan data

– No need for pattern design formula

– Intuitive garment design

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Pattern Design

2D Pattern CAD 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

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Pattern Design

2D Pattern CAD 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

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Pattern Design

2D Pattern CAD Systems Input Device

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Garment Digitizer

Pattern Scanner

Pattern Design

2D Pattern CAD Systems Output Device

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Plotter

Cutting PlotterHigh ply flatbed type cutting machine

Pattern Design

2D Pattern CAD 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

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Pattern Design

2D Pattern CAD Systems Software

Grading– Parametric design based method– Pattern shifting method– Cut and spread method

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Pattern Design

2D Pattern CAD Systems Software

Marking

– 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

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Pattern Design

2D Pattern CAD Systems Commercial Systems

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2D Pattern CAD

Basics Data Structure

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Line

Segment SegmentSegment

Reference to Point

Reference to Point

Reference to Point

......

Garment

Pattern Pattern Pattern

Cutline

Sewing Line

Internal Lines

Notch

Drill HolePoint

Grading Info.

......

MetaInformation(name, type, grain, etc.)

2D Pattern CAD

Basics Definition of Pattern Geometry

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Pattern

Sewing Line

Internal Line

Cut Line

GrainCornerPoint

CurveControl Point

Notch

Drill Hole

2D Pattern CAD

Basics Segment

Basic element of geometry definition

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Corner Point

Corner Point

Curve Control Point

Requirements for a segment

Must go through the given pointsLength can be calculatedArbitrary position can be determined on it

2D Pattern CAD

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

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2D Pattern CAD

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.

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2D Pattern CAD

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

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2D Pattern CAD

Basics Pattern Manipulation Example

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Delete point DivisionInternal linedefinition

Line reshaping

2D Pattern CAD

2D Pattern CAD 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

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2D Pattern CAD

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

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2D Pattern CAD

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

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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

2D Pattern CAD

Parametric Pattern Design Script Based Design

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2D Pattern CAD

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

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2D Pattern CAD

Parametric Pattern Design Interactive Design

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2D Pattern CAD

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

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2D Pattern CAD

Camera based Pattern Digitizer Principles of Camera Calibration

The image is distorted by the lens

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2D Pattern CAD

Camera based Pattern Digitizer Principles of Camera Calibration

Method to match the world coordinate with the camera coordinate

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Checkerboard(World Coordinate System)

x

y

Camera

Grid Reconstruction

2D Pattern CAD

Camera based Pattern Digitizer Isoparametric mapping

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0

1

1

0.30.4

0.3

0.4

(x3,y3) (x4,y4)

(x1,y1) (x2,y2)

2D Pattern CAD

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...

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2D Pattern CAD

Camera based Pattern Digitizer Techniques for Garment Pattern Recognition

Binarization

– Color image (RGB) into gray scale image :

– Gray scale image into binary into :

– Threshold value greatly affects the final product

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3

BlueGreenRedGray

Threshold)(Gray0

Threshold)(Gray1Value

2D Pattern CAD

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

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Thresholded Object Border pixels with 8-connectivity Thinned and traced contour

4-connectivity 8-connectivity

2D Pattern CAD

Camera based Pattern Digitizer Image Analysis

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2D Pattern CAD

Camera based Pattern Digitizer Image Analysis

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Saved as

DXF-AAMAfor

compatibility

DrawingeXchangeFormat

American Apparel Manufacturers Association

2D Pattern CAD

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.

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2D Pattern CAD

Pattern Marking System Principles of Marker Making

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Rasterization of Fabric and Patterns

All Patterns

Place Pattern

All Pattern Orders (n!)

Find Best Marker

Evaluate Efficiency

Rasterization of Pattern

Placement of a pattern on rasterized fabric

2D Pattern CAD

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

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Rectangle Bounding of Area

patterns placed of AreaEfficiency

First pattern

Better

Worse

Bounding Rectangle

2D Pattern CAD

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

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2D Pattern CAD

Pattern Marking System Principles of Marker Making

Constraints

– Marking on a complex shaped domain such as leather or fabric with defects

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