Binary Descriptors

One problem with traditional descriptors is that they consist of a vector of values, usually floating-point values because of normalization. Consequently, both extracting this vector and comparing descriptors require substantial computation. One promising alternative is to extract a binary vector as the descriptor. A binary vector requires less memory, and comparison requires only the Hamming distance between the corresponding binary strings. The Hamming distance can be computed very efficiently by XORing the binary strings and counting the set bits (POPCOUNT).