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A COMPARISON AND EVALUATION OF MOTION INDEXING ...

A COMPARISON AND EVALUATION OF MOTION INDEXING ...

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CHAPTER 6<br />

CONCLUSION <strong>AND</strong> FUTURE WORK<br />

In this thesis, several methods of motion indexing were implemented and com-<br />

pared. Dynamic Time Warping 3D-based technique was found to perform the best<br />

among all five techniques when compared by false positives and false negatives met-<br />

rics. The time performance of feature-based technique was found to be the best but<br />

at the same time the indexing performance was poor. Two PCA-based segmentation<br />

techniques were implemented and a new method was developed to perform indexing<br />

on these segments. Due to poor segments created by segmentation techniques, the<br />

indexing results of the new method were not satisfactory.<br />

The motion indexing problem can be generalized to consider sets of essential<br />

actuators instead of the whole body. This generalized problem will address the in-<br />

dexing and retrieval of a particular action even when spliced with other simultaneous<br />

actions.<br />

All the five techniques implemented consider all joints of the body to find a<br />

match. This leads to a mismatch in cases of hybrid motions where several motions<br />

are performed simultaneously. For example, a walk action combined with a hand wave<br />

cannot properly matched with either a walk query or a hand wave query. Methods<br />

can be developed which select a subset of joints relevant to the query ignoring the<br />

other joints while matching.<br />

Furthermore, uniform scaling in addition to Dynamic Time Warping can be<br />

used to improve results when matching sequences, where we stretch and compress the<br />

sequences by linearly re-sampling them to make the same lengths and then perform<br />

62

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