Computer-Assisted Bargello Quilt Design

[Pages:148]Computer-Assisted Bargello Quilt Design

by

Marge Coahran

A thesis submitted in conformity with the requirements for the degree of Master of Science

Graduate Department of Computer Science University of Toronto

Copyright c 2005 by Marge Coahran

Abstract

Computer-Assisted Bargello Quilt Design Marge Coahran Master of Science

Graduate Department of Computer Science University of Toronto 2005

Quilting is an art form in which amateur craftspeople explore geometry and color to create stunning designs. Bargello is a specific quilt style, defined by a clever construction method that imposes constraints on the designs and gives them a characteristic appearance. The current process for designing Bargello patterns is laborious and time-consuming. We have developed a prototype system in which users can design Bargello quilts quickly and easily by sketching curves with a mouse. The system has three constituent parts: an algorithm that produces visually smooth curves composed of corner-connected axisaligned rectangles, a module that supports the creation of Bargello quilt designs, and a module that supports the exploration of color combinations using real fabric textures. We conducted a set of informal focus group sessions with quilters from the community to evaluate the system. The participants were enthusiastic about the system and also provided suggestions for its improvement.

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Acknowledgements

Many people contributed to the success of this project and to the fullness of my experience here. My heartfelt thanks to you all:

To the many quilters who participated in focus groups and especially to Bette of the Simcoe County Quilt Shoppe, whose enthusiasm for this project was rivaled by none.

To the folk from Vermont who encouraged me to take this step, supported me in it, and gave me respite: Myra Cohen, Charlie Colbourn, Craig Damon, Alison Pechenick, Robert Snapp, Kathy Desjardins, and Cait Lloyd.

To the many dgp students and staff who taught me much and occasionally let me teach them as well: Wael Aboelsaadat, Gerard Baron, Hanieh Bastani, Anastasia Bezerianos, Patrick Coleman, Kevin Forbes, Irene Fung, John Hancock, Maciej Kalisiak, Alex Kolliopoulos, Azeem Lakdawalla, Joe Laszlo, Xia Liu, Noah Lockwood, Shahzad Malik, Mike McGuffin, Nigel Morris, Michael Neff, Mike Pratscher, Faisal Qureshi, Gonzalo Ramos, Abhishek Ranjan, Alan Rosenthal, Russell Schick, Patricio Simari, Maryam Tohidi, Chris Trendall, Fanis Tsandilas, Mike Tsang, Winnie Tsang, Dan Vogel, Jack Wang, Naiqi Weng, Daniel Wigdor, Mike Wu, Paul Yang, and Quinxin Yu. Especial thanks go to the "eccentric old codgers" among you, my fellow elfgroup students.

To the coffee klatch and lunch bunch gals who shared their stories and their desserts: Afra Alishahi, Faye Baron, Tobi Kral, Mahsa Moallem, Nina Theissen, Amber WilcoxO'Hearn, and Jane You.

To the faculty who gave me special challenges and helped me meet them: Derek Corneil, Suzanne Stevenson, Diane Horton, and Tom Fairgrieve. Also to Ron Baecker who, as second reader, pressed me to claim my contributions and mean it.

Most especially to Eugene Fiume who was just the supervisor I needed ? for enthusiastically supporting this unorthodox project, for valuing authentic applicability in research, and for caring more about students than computer graphics. Your consistent kindness, inexhaustible cheerfulness, and apparent imperturbability challenge us all.

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Contents

1 Introduction

1

1.1 The art of quilting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2 Bargello quilts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.3 Computer graphics: related work . . . . . . . . . . . . . . . . . . . . . . 14

1.4 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2 Bargello Curve Generation

23

2.1 Fitting curves to data points . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.1.1 Text character contours . . . . . . . . . . . . . . . . . . . . . . . 25

2.1.2 Experimental data streams . . . . . . . . . . . . . . . . . . . . . . 29

2.1.3 Interactive drawings . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.1.4 Bargello curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2.2 Rasterizing geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

2.2.1 Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

2.2.2 Cubic curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

2.2.3 Text characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

2.2.4 Tiled Bargello curves . . . . . . . . . . . . . . . . . . . . . . . . . 48

3 Computer-Assisted Bargello Quilt Design

65

3.1 Fabric selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

3.2 Bargello design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

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3.2.1 Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 3.2.2 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 3.3 Image gallery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

4 System Evaluation

102

4.1 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

4.2 Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

4.2.1 Challenging aspects of quilt design . . . . . . . . . . . . . . . . . 108

4.2.2 Kudos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

4.2.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

4.2.4 Problems and concerns . . . . . . . . . . . . . . . . . . . . . . . . 113

4.2.5 Responses to proposed future work . . . . . . . . . . . . . . . . . 116

4.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

5 Conclusion

121

5.1 Accomplishments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

5.2 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

5.3 Lessons learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

5.4 Open questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Bibliography

134

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List of Tables

3.1 Data dictionary: BargelloCurve. . . . . . . . . . . . . . . . . . . . . . . . 88 3.2 Data definition: bitmap element. . . . . . . . . . . . . . . . . . . . . . . 90 3.3 Data definition: design region. . . . . . . . . . . . . . . . . . . . . . . . . 92 3.4 Data definition: SelectRange. . . . . . . . . . . . . . . . . . . . . . . . . 94 4.1 Focus group demographics . . . . . . . . . . . . . . . . . . . . . . . . . . 104 4.2 Focus group questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

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List of Figures

1.1 Honeycomb quilt, c. 1815 . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Chintz applique quilt, c. 1840 . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Pieced quilt, c. 1880-1900 . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4 Landscape quilt, 1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.5 Simultaneous color contrast . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.6 Traditional Bargello design . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.7 Bargello construction process . . . . . . . . . . . . . . . . . . . . . . . . 8 1.8 Local parallelity and symmetry in Bargello curves. . . . . . . . . . . . . 10 1.9 Contemporary Bargello design . . . . . . . . . . . . . . . . . . . . . . . . 11 1.10 Bargello design process . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.1 Curve generation: culled data points. . . . . . . . . . . . . . . . . . . . 37 2.2 Curve generation: characteristic points. . . . . . . . . . . . . . . . . . . 38 2.3 Curve generation: piecewise cubic Hermite curve. . . . . . . . . . . . . . 39 2.4 Scan-conversion hazards. . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 2.5 Bargello rasterization: stretched Hermite curve. . . . . . . . . . . . . . . 52 2.6 Bargello rasterization: initial tile path. . . . . . . . . . . . . . . . . . . . 53 2.7 Bargello rasterization: beautification . . . . . . . . . . . . . . . . . . . . 54 2.8 Bargello rasterization: tile subdivisions . . . . . . . . . . . . . . . . . . . 58 2.9 Design column subdivisions . . . . . . . . . . . . . . . . . . . . . . . . . 59 2.10 Bargello tile path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

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2.11 Independent Bargello tile paths. . . . . . . . . . . . . . . . . . . . . . . . 64 3.1 Sample fabric combinations . . . . . . . . . . . . . . . . . . . . . . . . . 68 3.2 Fabric selection module . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 3.3 HWB color space. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 3.4 Main color wheel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 3.5 Fabric browser. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 3.6 Fabric palettes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 3.7 Color composition wheel. . . . . . . . . . . . . . . . . . . . . . . . . . . 79 3.8 Bargello design: Traditional, with staggered seams. . . . . . . . . . . . . 80 3.9 Reflection template. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 3.10 Bargello design: Symmetrical, with matched seams. . . . . . . . . . . . 83 3.11 Bargello design: Solid color tiles. . . . . . . . . . . . . . . . . . . . . . . 97 3.12 Bargello design: Watercolor effect. . . . . . . . . . . . . . . . . . . . . . . 98 3.13 Bargello design: Arches. . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 3.14 Bargello design: Crossroads. . . . . . . . . . . . . . . . . . . . . . . . . . 99 3.15 Bargello design: Lattice. . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 3.16 Bargello design: Weave. . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 3.17 Bargello design: Purple maze. . . . . . . . . . . . . . . . . . . . . . . . . 100 3.18 Bargello design: Heart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 3.19 Bargello design: Birds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 4.1 Focus group participant's Bargello design. . . . . . . . . . . . . . . . . . 105 5.1 Curve editing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

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