1. A method for identifying a complex-object in a query image, the method comprising: performing computer-enabled steps of: processing at least one pixel patch from the query image with a cascade of classifiers, each classifier of the cascade configured to identify at least one discriminative feature characteristic of a part of the complex-object, wherein each successive classifier of the cascade identifies a number of discriminative features greater than a number of discriminative features identified by prior classifiers of the cascade; and selecting an additional pixel patch from the query image for processing after a last classifier of the cascade has identified the distinguishing feature, the selecting based on a known positional relationship between the part and an additional part of the complex-object.