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Proceedings Paper

An improved SIFT descriptor
Author(s): Luan Zeng; You Zhai
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Paper Abstract

In order to improve the robustness and real time performance of SIFT based image registration algorithms, a new descriptor is proposed. We compute the new descriptor for a log-polar location grid with 3 bins in radial direction (the radius set to 3, 6 and 8) and 12 in angular direction, which results 36 location bins. Firstly, the 3×12 log-polar location grid is rotated to align its dominant orientation to a canonical direction in a different way with SIFT with less computational complexity. The keypoint dominant orientation and its orthogonal orientation is defined as the x and y directions of the descriptor’s local coordinate system. After that a 3×3 grid is rotated to align the dominant orientation ,and then the rotated 3×3 grid is translated to each pixel within the local 3×12 log-polar location grid. Therefore the local 3×12 log-polar location grid is rotated to align the dominant orientation and the rotation invariance is achieved. Secondly, compute the gradients in x and y directions using the rotated 3×3 grid for each pixel within the keypoint local neighborhood, so each pixel constitutes a gradient vector with 2 dimensions. Thirdly, use the distance from each pixel to the corresponding keypoint and a Gaussian function to assign a weight to the gradients, and then compute the gradients location histogram for the 36 location bins in the 3×12 log-polar grid. Finally, a descriptor with 72 dimensions is constituted and the descriptor is normalized to achieve illumination invariance. The experimental results show that the computational complexity of the new descriptor is reduced about 30% compared with the standard SIFT descriptor while the performance is favorably compared to the standard SIFT descriptor .

Paper Details

Date Published: 16 November 2011
PDF: 8 pages
Proc. SPIE 8321, Seventh International Symposium on Precision Engineering Measurements and Instrumentation, 83210O (16 November 2011); doi: 10.1117/12.903778
Show Author Affiliations
Luan Zeng, The Academy of Equipment Command and Technology (China)
You Zhai, The Academy of Equipment Command and Technology (China)


Published in SPIE Proceedings Vol. 8321:
Seventh International Symposium on Precision Engineering Measurements and Instrumentation
Kuang-Chao Fan; Man Song; Rong-Sheng Lu, Editor(s)

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