A method for classification of a target object having a periphery comprises the steps of: selecting a plurality of random first chords D1 across the periphery of the target object; measuring each of the first chords D1 to obtain a plurality of first dimensions; computing for each of the first chords D1 a second chord D2 across the periphery thus forming a plurality of D1, D2 pairs of chords; measuring the second chords D2 for all pairs to obtain second dimensions; computing for each of the pairs of first chords D1 and second chords D2 the ratio D1/D2 of the first dimension to the second dimension to obtain a plurality of first values; computing the logarithm of the first values to obtain a plurality of logarithmic values; computing difference values by subtracting the second dimension from the first dimension for each of the pairs; recording the first values, logarithmic values and difference values in histograms; extracting a vertex lists from the histograms; combining one or more of the vertex lists to obtain a signature indicative of the classification of the object target. For each of the pairs, the second chords are orthogonal to the first chords, and the second chords share a point with the first chords and the periphery.