1. In a graphical information system (GIS), a method for processing a digital image depicting one or more physical objects to locate a feature in the digital image, the method comprising the following: by a processor, executing a pixel-level cue algorithm to identify an interesting area of a raster image depicting the one or more physical objects; determining a pixel-level probability that the interesting area of the raster image identified is the feature using a result from the pixel-level cue algorithm; comparing the pixel-level probability to a pixel-level cue threshold; and if the pixel-level probability satisfies the pixel-level cue threshold: converting at least a portion of the raster image to a vector layer by geometric modeling using points, lines, curves, and polygons to generate a representation of digital vector objects represented by the points, lines, curves and polygons; executing an object-level cue algorithm on the vector layer to identify an interesting area of the vector layer; determining an object-level probability that the interesting area of the vector layer is the feature using a result of the pixel-level cue algorithm; and comparing the object-level probability to an object-level threshold.