Fourier Preprocessing for Hand Print Character Recognition

Granlund, Gösta H.

doi:10.1109/tc.1972.5008926

Cited by 513 publications

(232 citation statements)

References 5 publications

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“…Fourier descriptors have some important properties, such as translation invariance, scale and rotation invariant. Therefore, FDs have been employed for pattern recognition, shape discrimination and hand print character recognition of plane closed curves due to these advantages (Borchert et al, 2014;Granlund, 1972;Li et al, 2006;Persoon and King-Sun, 1977;Zahn and Roskies, 1972). The Fourier descriptors based on the shape radii are given by (Gonzalez and Woods, 2008) …”

Section: Fourier Transformmentioning

confidence: 99%

Stereo imaging camera model for 3D shape reconstruction of complex crystals and estimation of facet growth kinetics

Zhang

Cai

Liu

et al. 2017

Chemical Engineering Science

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The principle that the 3D shape of crystals that grow from a solution can be characterised in real-time using stereo imaging has been demonstrated previously. It uses the 2D images of a crystal that are obtained from two or more cameras arranged in defined angles as well as a mathematical reconstruction algorithm. Here attention is given to the development of a new and more robust 3D shape reconstruction method for complicated crystal structures. The proposed stereo imaging camera model for 3D crystal shape reconstruction firstly rotates a digitised crystal in the three-dimensional space and varies the size dimensions in all face directions. At each size and orientation, 2D projections of the crystal, according to the angles between the 2D cameras, are recorded. The contour information of the 2D images is processed to calculate Fourier descriptors and radius-based signature that are stored in a database. When the stereo imaging instrument mounted on a crystalliser captures 2D images, the images are segmented to obtain the contour information and processed to obtain Fourier descriptors and radius-based information. The calculated Fourier descriptors and radius-based signature are used to find the best matching in the database. The corresponding 3D crystal shape is thus found. Potash alum crystals that each has 26 habit faces were used as a case study. The result shows that the new approach for 3D shape reconstruction is more accurate and significantly robust than previous methods. In addition, the growth rates of {111}, {110} and {100} faces were correlated with relative supersaturation to derive models of facet growth kinetics.

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Section: Fourier Transformmentioning

confidence: 99%

Stereo imaging camera model for 3D shape reconstruction of complex crystals and estimation of facet growth kinetics

Zhang

Cai

Liu

et al. 2017

Chemical Engineering Science

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“…Adopting the notation in [8], the closed contour c with coordinates x and y is parameterized as a complex valued periodic function…”

Section: Fourier Descriptorsmentioning

confidence: 99%

Using Fourier Descriptors and Spatial Models for Traffic Sign Recognition

2011

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Abstract. Traffic sign recognition is important for the development of driver assistance systems and fully autonomous vehicles. Even though GPS navigator systems works well for most of the time, there will always be situations when they fail. In these cases, robust vision based systems are required. Traffic signs are designed to have distinct colored fields separated by sharp boundaries. We propose to use locally segmented contours combined with an implicit star-shaped object model as prototypes for the different sign classes. The contours are described by Fourier descriptors. Matching of a query image to the sign prototype database is done by exhaustive search. This is done efficiently by using the correlation based matching scheme for Fourier descriptors and a fast cascaded matching scheme for enforcing the spatial requirements. We demonstrated on a publicly available database state of the art performance.

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“…The minimization of that distance leads to estimates of the pose. Fourier descriptors in CGA Fourier descriptors are often used for object recognition [5] and affine pose estimation [1] of closed contours. We are now concerned with the formalization of 3D Fourier descriptors in CGA.…”

Section: The Pose Problem In Conformal Geometric Algebramentioning

confidence: 99%

Pose Estimation of Free-Form Surface Models

Rosenhahn

Perwass

Sommer

2003

Lecture Notes in Computer Science

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Abstract. In this article we discuss the 2D-3D pose estimation problem of 3D free-form surface models. In our scenario we observe free-form surface models in an image of a calibrated camera. Pose estimation means to estimate the relative position and orientation of the 3D object to the reference camera system. The object itself is modelled as a twoparametric surface model which is represented by Fourier descriptors. It enables a low-pass description of the surface model, which is advantageously applied to the pose problem. To achieve the combination of such a signal-based model within the geometry of the pose scenario, the conformal geometric algebra is used and applied.

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Fourier Preprocessing for Hand Print Character Recognition

Cited by 513 publications

References 5 publications

Stereo imaging camera model for 3D shape reconstruction of complex crystals and estimation of facet growth kinetics

Stereo imaging camera model for 3D shape reconstruction of complex crystals and estimation of facet growth kinetics

Using Fourier Descriptors and Spatial Models for Traffic Sign Recognition

Pose Estimation of Free-Form Surface Models

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