IFA offers a means for automatic tracking initialization and reinitialization after environmental conditions momentarily deteriorate and cause the system to lose track of its target. Systems based on the framework degrade gracefully as various assumptions about the environment are violated. In particular, when constructed with multiple tracking algorithms of varying precision, the failure of a single algorithm causes another, less precise algorithm to take over, thereby allowing the system to return approximate information on feature location or configuration. Experiments show that tracking systems based on the IFA framework are extremely robust to any type of temporary visual disturbance. IFA Framework and Algorithm The IFA framework is organized into layers.
Layers take as input and return as output sets of object states.
Each layer excises unlikely configurations from its input set and passes a smaller output set on to the next layer. The topmost layer outputs a small set of configurations that pinpoints the target state at the precision desired. Each layer is based on tracking algorithms or search heuristics. At any instant in time, processing occurs only in a single layer. If the output set is believed to contain the target state, processing proceeds up the framework, and otherwise, processing reverts back down the layers.