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An extended-HCT semantic description for visual place recognition

We describe a new semantic descriptor for robots to recognize visual places. The descriptor integrates image features and color information via the hull census transform (HCT) and image histogram indexing. Our approach extracts the semantic description based on the convex hull points and statistical calculation. The color histograms are then formed by four indices and added to the descriptor. The semantic codebook consists of several places with many image descriptors. Finally, a one-versus-one (OVO) multi-class support vector machine (SVM) is used to model the places. The proposed technique is achieved by using a high-level cue integration scheme based on the learning information over the color and feature space to optimally combine the weighted cues. It is suitable for visual place recognition, particularly for the images captured by an omnidirectional camera. The experimental results show that the codebook with less vectors is as robust as most popular codebooks under varying environments. The performance is evaluated and compared with several state-of-the-art descriptors.