Conference Paper

An Affine Invariant Region Detector Using the 4th Differential Invariant

Nat. Univ. of Defense Technol., Changsha
DOI: 10.1109/ICTAI.2007.112 Conference: Tools with Artificial Intelligence, 2007. ICTAI 2007. 19th IEEE International Conference on, Volume: 1
Source: IEEE Xplore


A novel affine invariant region detector based on the 4th differential invariant (DI4) is proposed in this paper. The detector combines scale-space theory with an autocorrelation matrix. Since it is proved that DI4 is a scale- space selection function, feature points and their characteristic scales are first detected by the local maxima of the normalized DI4 over scale-space. Then, the auto-correlation matrices, which are used to describe the affine shapes, are estimated on the characteristic scales of the feature points. The ellipse regions given by the auto-correlation matrices are affine invariant. In order to verify the affine invariance, we build up a simulation experiment to test affine invariance using two single- parameter transforms. The experimental results show the detected regions are invariant to rotation, scale and affine transforms as well as robust to illumination changes.

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