Capturing outlines of 2D objects with Bézier cubic approximation

Masood, Asif; Sarfraz, Muhammad

doi:10.1016/j.imavis.2008.07.012

Cited by 19 publications

(5 citation statements)

References 37 publications

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“…The main principle of our image processing is schematically represented in Figure 3 . Here, the shape of the PC and the posterior IOL surface was first approximated by a Bézier spline, [ 19 ] i.e., a series of cubic Bézier curves joined end-to-end in control points. The control points (the white points in the top left picture in Figure 3 ) were manually selected by an ophthalmologist (G.H.)…”

Section: Methodsmentioning

confidence: 99%

Optical coherence tomography for an in-vivo study of posterior-capsule-opacification types and their influence on the total-pulse energy required for Nd:YAG capsulotomy: a case series

et al. 2014

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BackgroundPosterior capsule opacification (PCO) is the most common post-operative complication associated with cataract surgery and is mostly treated with Nd:YAG laser capsulotomy. Here, we demonstrate the use of high-resolution spectral-domain optical coherence tomography (OCT) as a technique for PCO analysis. Additionally, we evaluate the influence of PCO types and the distance between the intraocular lens (IOL) and the posterior capsule (PC), i.e., the IOL/PC distance, on the total-pulse energy required for the Nd:YAG laser posterior capsulotomy.Methods47 eyes with PCO scheduled for the Nd:YAG procedure were examined and divided into four categories: fibrosis, pearl, mixed type and late-postoperative capsular bag distension syndrome. Using custom-made computer software for OCT image analysis, the IOL/PC distances in two dimensions were measured. The IOL/PC distances were compared with those of a control group of 15 eyes without PCO. The influence of the different PCO types and the IOL/PC distance on the total-pulse energy required for the Nd:YAG procedure was analyzed.ResultsThe total-pulse energy required for a laser capsulotomy differs significantly between PCO types (p = 0.005, Kruskal-Wallis test). The highest energy was required for the fibrosis PCO type, followed by mixed, pearl and late-postoperative capsular bag distension syndrome. The IOL/PC distance also significantly influenced the total-pulse energy required for laser capsulotomy (p = 0.028, linear regression). Lower total-pulse energy was expected for a larger IOL/PC distance.ConclusionsOur study indicates that the PCO types and the IOL/PC distance influence the total-pulse energy required for Nd:YAG capsulotomy. The presented OCT method has the potential to become an additional tool for PCO characterization. Our results are important for a better understanding of the photodisruptive mechanisms in Nd:YAG capsulotomy.

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Section: Methodsmentioning

confidence: 99%

Optical coherence tomography for an in-vivo study of posterior-capsule-opacification types and their influence on the total-pulse energy required for Nd:YAG capsulotomy: a case series

et al. 2014

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“…A variety of corner detection algorithms are available in the literature. 16,24,36,37 An algorithm by Sarfraz et al 35 is selected for its accuracy and efficiency. Summary of algorithm 35 is given below.…”

Section: Boundary Segmentationmentioning

confidence: 99%

“…New positions of control points P 1 and P 2 are computed as newP 1~o ldP 1 zE 1 (16) newP 2~o ldP 2 zE 2…”

Section: Approximation Using a Cubic Bezier Curvementioning

confidence: 99%

“…In addition to data reduction, this approach also provides translation, scaling, rotation and deformation of shapes without any loss of quality. It has broad range of applications in font designing, 16 data visualisation, 17 digitisation of hand-drawn shapes, 18 computer-aided design (CAD), 19,20 computer-aided manufacturing (CAM) and computer-aided geometric design. There is a wide variety of outline capturing techniques 15,[21][22][23][24][25][26][27][28][29][30][31][32][33] available in the literature.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optimal curve fitting approach to represent outlines of 2D shapes

Masood¹,

Ejaz²

2010

The Imaging Science Journal

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A new outline capturing system is presented in this paper. It employs Bezier curve for curve approximation. Approximation starts with an initial estimation of control points positions, which is updated iteratively based on computed error. Consequently, the control points converge to an optimum position. The segments obtained after corner detection are initially approximated with Bezier curve of lowest degree, i.e. degree 1. The degree of approximating curve is then increased iteratively until the error comes under the user specified limit. This ensures optimal fit with least number of control points. Shape representation results of proposed algorithm are compared with existing techniques. Experimental results show that proposed algorithm can approximate the 2D shapes with considerably less number of control points, when compared with existing techniques. Computational efficiency is another advantage of proposed algorithm. Presented algorithm can have very useful applications in CAD/CAGD and real-time computer vision algorithms.

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“…So the row and column co-ordinates of each point on the boundary can be expressed as a complex number. For details, the reader is referred to [5,14]. This paper implements a simple classifier that calculates similarity measure, namely Euclidean Distance (ED), of the corresponding Fourier descriptors of the input shape.…”

Section: Fourier Theory and Similarity Measurementioning

confidence: 99%