Keypoint descriptor generation by complex wavelet analysis

摘要

The present application relates to a method of generating a keypoint descriptor for identifying an object in an image or a sequence of images, the keypoint descriptor being substantially invariant to a transformation of the object in the image. The method includes receiving object data representing an object for identification in an image; processing the object data to generate at least one basis function representing a feature having undergone at least one transformation or a transformation sequence across several consecutive frames, optionally using transformations that are out of a plane of the image to recognize objects from multiple views; modifying a prototype wavelet function based on the at least one basis function to generate a plurality of modified wavelet functions; comparing the plurality of modified wavelet functions with the at least one basis function; selecting a modified wavelet function of the plurality of modified wavelet functions based on the comparison of the plurality of modified wavelet functions with the at least one basis function; and processing an input image or input orientation field according to the selected modified wavelet function to generate the keypoint descriptor. The present application further relates to a method of identifying an object in an image using a keypoint descriptor; and processing apparatus and computer program products for implementing a method of the present application.

主权项

1. A method of generating a keypoint descriptor for identifying an object in an image, wherein the keypoint descriptor is substantially invariant to a transformation of the object in the image, the method comprising:
receiving object data indicative of an object for identification in an image, the image having an image plane associated therewith; generating, by processing the received object data, at least one basis function representing a feature having undergone at least one transformation, using transformations that are out of the image plane to recognize objects from multiple views; modifying a prototype wavelet function based on the at least one basis function to generate a plurality of modified wavelet functions; comparing the plurality of modified wavelet functions with the at least one basis function; selecting a modified wavelet function of the plurality of modified wavelet functions based on the comparison of the plurality of modified wavelet functions with the at least one basis function; and generating the keypoint descriptor by processing at least one of an input image or an input orientation field according to the selected modified wavelet function to, wherein the object is a three-dimensional object in a three-dimensional image and the keypoint descriptor is configured to identify an object in a series of images spaced over time, and wherein the prototype wavelet function and the plurality of modified wavelet functions comprise a radial distance component, and azimuthal angle component and a polar angle component, the prototype wavelet function and the plurality of modified wavelet functions having the formula;
Ψk(d,θ,φ)=dnk−1e−αkd(nk−αkd)·(cos(mkθ)+qx sin(mkθ))·(cos(lkφ)+qy sin(lkφ)) where the term dnk−1e−αkd(nk−αkd) is the radial distance weighting component with radial distance, d, the term (cos(mkθ)+qxsin(mkθ)) is the azimuthal angle component with azimuthal angle θ, and the term (cos(lkφ)+qysin(lkφ)) is the polar angle component with polar angle Ψ, and where the terms qx and qy denote unit quaternions and obey the rules qx2=qy2=qz2=−1, and qxqy=qz.