  Distance transforms are a central tool in shape analysis, morphometry, and
curve evolution problems. This work describes and investigates an artifact
present in distance maps computed from sampled signals. Namely, sampling
reflects through the distance transform causing quantization in the resulting
distance map. Gradients of the quantized distance map show banding, affecting
the quality of subsequence processing. Furthermore, this error is independent
of the sampling period of the signal and cannot be removed by modifying the
number of samples across an objects width. Where needed, distance maps should
be computed from representations other than binary images. In the case where
exact representations are needed, a dithering and noise removal algorithm is
proposed.
