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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