Encyclopedia of Biometrics

2009 Edition
| Editors: Stan Z. Li, Anil Jain

Interest Point, Region, Local Feature

Reference work entry
DOI: https://doi.org/10.1007/978-0-387-73003-5_389

In a way, the ideal local feature is a point as defined in geometry: having a location in space but no spatial extent. In practice however, images are discrete with the smallest spatial unit being a pixel and discretization effects playing an important role. To localize features in images, a local neighborhood of pixels need to be analyzed, giving all local features some implicit spatial extent. For some applications (e.g., camera calibration or 3D reconstruction), this spatial extent is completely ignored in further processing, and only the location derived from the feature extraction process is used. In those cases, one typically uses the term interest point. However, in most applications those features also need to be described, such that they can be identified and matched, and this again calls for a local neighborhood of pixels. Often, this neighborhood is taken equal to the neighborhood used to localize the feature, but this need not be the case. In this context, one typically...

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© Springer Science+Business Media, LLC 2009