Setting Tracker Parameters

The IPAN Tracker has three basic parameters to be set: the speed limit $v_{max}$, the verification depth $N_{ver}$, and the cost limit $\delta_{max}$.

The upper limit of the speed $v_{max}$ is a critical parameter: the closer the estimate the better the performance, in both tracking quality and processing time. If $v_{max}$ is smaller than the actual maximum speed, some links will be lost, as they fall outside the search area. Setting $v_{max}$ to a `safe' large value is not a good solution either, as the search area looses its selective role: the processing time will grow, together with the probability of false links.

As it was experienced earlier for the original algorithm [2], the verification depth $N_{ver}=2$ brings a significant improvement in the performance compared to $N_{ver}=1$. Further increase of $N_{ver}$ has only minor influence on the tracking accuracy, while the computational load increases. Verification depths $N_{ver}>2$ should only be considered in the case of extremely dense point sets.

The optimal value of the cost limit $\delta_{max}$ depends on the character of motion. For smooth motion, $\delta_{max}$ can be set relatively low; to allow for more drastic turns or speed changes, it should to be set closer to $1$. Currently, we use $\delta_{max}=0.6$; however, this setting does not seem to be too critical. Two additional, `hidden' parameters specify the spatial resolution of the search for occluded points in the post-processing procedure. (See section 4.3.) We use $\Delta \theta = 10^{\circ }$ and $\Delta v = 1$ pixel as fixed default values.