# [feat] Change keypoints registration/extraction parameters

- Change default min distance to sensor from 3m to 1.5m (1m causes trouble with some datasets) because a lot of datasets (particularly indoor ones) needs this parameter setting.
- The PCA relative params are modified :
- The first idea was to replace the planarity/linearity thresholds that are not really intuitive by the state of the art reference ones, respectively (l1 - l0)/l2 and (l2 - l1)/l2.
- However, this lead to not so intuitive values because of the low number of points that is used to fit the models (edge/planes).
- Moreover, in the plane case, the smallest eigen value is already checked when thresholding the MSE value and the same is done in the edge case with the two smallest eigen values.
- Therefore, the only check that is kept is to ensure the plane points do not lay on a line which would lead to a false normal computation. To do so, we compare the two highest eigen values, we chose l1/l2 to keep the value between 0 and 1. A 1/5 ratio is chosen as default limit. WARNING : the eigen values ratio is equivalent to the neighborhood main directions expansion ratio
**SQUARED**. Therefore, if one wants to filter only planar patches that have a ratio of 1/5 between its 2 main directions, he has to put a value of 1/25 between the patch main eigen values.

Example of improvements on the trajectory in an indoor context (red = master, white = this MR result)

@jerome.dias PTAL