3. A computer implemented method for object tracking, comprising: accessing a video feed that captures an object in at least a portion of the video feed; operating a generative tracker to capture appearance variations of the object in the video feed; operating a discriminative tracker to discriminate the object from the object's background as captured by the video feed, wherein operating the discriminative tracker comprises using a sliding window to process data from the video feed, and advancing the sliding window to focus the discriminative tracker on recent appearance variations of the object in the video feed; and training the generative tracker and the discriminative tracker based on the video feed, wherein the training comprises updating the generative tracker based on an output of the discriminative tracker, and updating the discriminative tracker based on an output of the generative tracker; and tracking the object with information based on an output from the generative tracker and an output from the discriminative tracker.
3. A computer implemented method for object tracking, comprising: accessing a video feed that captures an object in at least a portion of the video feed; operating a generative tracker to capture appearance variations of the object in the video feed; operating a discriminative tracker to discriminate the object from the object's background as captured by the video feed, wherein operating the discriminative tracker comprises using a sliding window to process data from the video feed, and advancing the sliding window to focus the discriminative tracker on recent appearance variations of the object in the video feed; and training the generative tracker and the discriminative tracker based on the video feed, wherein the training comprises updating the generative tracker based on an output of the discriminative tracker, and updating the discriminative tracker based on an output of the generative tracker; and tracking the object with information based on an output from the generative tracker and an output from the discriminative tracker. 5. The method of claim 3 , wherein operating the generative tracker comprises: generating a compact representation of a complete appearance of the object based on linear subspaces to represent appearance variations of the object, wherein the linear subspaces are updated adaptively using an online learning algorithm.