1. A method for generating a local feature descriptor for an image, comprising: identifying a point within a first scale space from a plurality of scale spaces for an image; obtaining a plurality of image derivatives for each of the plurality of scale spaces; obtaining a plurality of orientation maps for each scale space in the plurality of scale spaces, where each of the plurality of orientation maps is obtained from non-negative values of a corresponding image derivative; for each scale space in the plurality of scale spaces, smoothing each of the plurality of orientation maps to obtain a corresponding plurality of smoothed orientation maps; and sparsely sampling a plurality of smoothed orientation maps corresponding to two or more scale spaces from the plurality of scale spaces to generate a local feature descriptor for the point wherein each of the smoothed orientation maps that is sparsely sampled is derived using a different orientation map than each of the other smoothed orientation maps that is sparsely sampled.