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Unformatted text preview: Assignment 2 -- Corner Finding CAP6105 Due: 10/2/09 11:59pm This purpose of this assignment is twofold. First, it is designed to give you a feel for the intricacies and complexities of corner finding, an important tool used in gesture and sketch-based interfaces. Second, it is to give you experience in implementing a state of the art algorithm from a research paper and to study its performance. Requirements There are two main requirements for this assignment. First, you will implement IStraw, a corner finding technique that was published in the Eurographics Symposium on Sketch- Based Interfaces and Modeling in August 2009. The paper is attached to this document. Second, you will compare this algorithm to the cusp finding algorithm found in starPad. Finally, as part of your deliverables, you are to provide a 1 page report on how IStraw compares to starPad’s cusp finder. Testing To test the corner finding algorithms, create a set of polyines based on the ones found in the IStraw paper. You should create 5 to 10 samples of each polyline you find in the paper. Deliverables You must submit a zip file containing your source and any relevant files needed to compile and run your application. Also include your report and a README file describing what works and what does not, any known bugs, and any problems you encountered. To submit, you can email me your zip file. Grading Grading will be loosely based on the following: 70% correct implementation of IStraw 20% analysis of IStraw compared to starPad’s cusp finder 10% documentation EUROGRAPHICS Symposium on Sketch-Based Interfaces and Modeling (2009) C. Grimm and J. J. LaViola Jr. (Editors) Revisiting ShortStraw – Improving Corner Finding in Sketch-Based Interfaces Yiyan Xiong † and Joseph J. LaViola Jr. ‡ University of Central Florida, School of EECS, Orlando, FL USA Abstract We present IStraw, a new corner finding technique based on an analysis of the ShortStraw algorithm. Our analysis reveals several limitations in ShortStraw and we develop techniques to overcome them. We also present an exten- sion to our corner finding approach for dealing with ink strokes that contain curves and arcs. An evaluation of our approach shows significant accuracy improvements over ShortStraw for polyline ink strokes with and without curves using an all-or-nothing accuracy metric while still maintaining ShortStraw’s computational complexity. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation—Line and curve generation H.5.2 [Computer Graphics]: User Interfaces—Graphics user interfaces 1. Introduction Corner finding is a fundamental component in creating pen- based interfaces. Since it is often used in the segmentation of ink strokes into lower level primitives, it is one of the most important steps in the process of free-form sketch recogni- tion and understanding [ KS05 , AD05 , HD04 , HR07 , PH08 ]....
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- Spring '09
- Machine Learning, Computer vision, Type I and type II errors, The Corner, ShortStraw