GeoLight (version 2.0.0)

distanceFilter: Filter for unrealistic positions within a track based on distance

Description

The filter identifies unrealistic positions. The maximal distance per hour/day can be set corresponding to the particular species.

Usage

distanceFilter(tFirst, tSecond, type, twl, degElevation = -6, distance, units = "hour")

Arguments

tFirst

vector of sunrise/sunset times (e.g. 2008-12-01 08:30).

tSecond

vector of of sunrise/sunset times (e.g. 2008-12-01 17:30).

type

vector of either 1 or 2, defining tFirst as sunrise or sunset respectively.

twl

data.frame containing twilights and at least tFirst, tSecond and type (alternatively give each parameter separately).

degElevation

sun elevation angle in degrees (e.g. -6 for "civil twilight")

distance

the maximal distance in km per units. Distances above will be considered as unrealistic.

units

the time unite corresponding to the distance. Default is "hour", alternative option is "day".

Value

Logical vector. TRUE means the particular position passed the filter.

Details

Note that this type of filter significantly depends on the calibration (degElevation). Especially during equinox periods. In contrast, the (loessFilter) is independent from positions (uses twilight times) and therefore superior.