首先，明确Tracking的定义：
在视频序列的第一帧标定跟踪目标，通过追踪算法对接下去每一帧中的目标位置做出预测。
接下来通过介绍几个名词，我们将这个大任务拆分成几个子任务：
1、Motion Model 运动模型
The motion model is just a fancy way of saying that you know the location and the velocity ( speed + direction of motion ) of the object in previous frames. If you knew nothing else about the object, you could predict the new location based on the current motion model, and you would be pretty close to where the new location of the object is.
2、 appearance model
But we have more information that just the motion of the object. We know how the object looks in each of the previous frames. In other words, we can build an appearance model that encodes what the object looks like. This appearance model can be used to search in a small neighborhood of the location predicted by the motion model to more accurately predict the location of the object.
The motion model predicts the approximate location of the object. The appearance model fine tunes this estimate to provide a more accurate estimate based on appearance.