Prewarping Siamese Network: Learning Local Representations for Online Signature Verification
We propose a neural network based framework for learning local representations of multivariate time series, and demonstrate its effectiveness for online signature verification. In contrast to related works that optimize a global distance objective, we incorporate a Siamese network into dynamic time warping (DTW) leading to a novel prewarping Siamese network (PSN) optimized with a local embedding loss. PSN learns a feature space that preserves the temporal location wise distances of local structures. Local embedding, along with the alignment conditions of DTW, imposes a temporal consistency constraint on the sequence level distance measure while achieving invariance as regards non linear distortions. Validation on online signature verification datasets demonstrates the advantage of our framework over existing techniques that use either handcrafted or learned feature representations.
ICASSP 2019 2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)