Friday, February 29, 2008

Temporal Classification: Extending the Classification Paradigm to Multivariate Time Series (Kadous)

Summary (ONLY intro and 6.3.2 - Auslan):

Kadous' thesis deals with machine learning in domains where values vary over time, including gesture recognition. His method involves using metafeatures of the data, which capture properties including temporal data, so a local maximum in height might be noted. He considers synthetic events combined with metafeatures, or "interesting examples", where a local maximum occurs near the nose or near the chin, which can lead to two very different classifications.

One application he tests his classifier on is Auslan (Australian sign language). He acknowledges that fingerspelling is not sufficient for proper communication, so focuses on whole signs. A sign is made up of handshape, location, orientation, movement, and expression (such as raising eyebrows to make a question).

He tested his classifier, which tries many different machine learning methods, on data from a Nintendo Powerglove as well as on data from 5DT gloves with a Flock-of-Birds tracker for each hand. The Powerglove data was one-handed, included one user's data, and totalled 1900 signs. The Flock data was two-handed, gave more data per hand, and had significantly less noise, and it was collected from one native Auslan signer over a period of 9 weeks, totalling 27 samples for sign, making 2565 signs.

short notes:
-powerglove low accuracy, HMM best
-flock good accuracy, adaboost best, maybe HMM not so good because of too many more channels of data
-rules formed for classification

Discussion:

It was nice to see data from a native signer, although it sounded a bit more exciting before I realized it was only one signer. I think this paper includes some interesting machine learning techniques, though I didn't look too closely at the parts of the thesis focusing on that rather than the sign language study. His data set is available at http://archive.ics.uci.edu/ml/datasets/Australian+Sign+Language+signs+(High+Quality) which could be nice to have in order to compare different, new techniques to published results.

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