Traj3DFromCoords creates a new 3-dimensional trajectory object from a
set of 3-dimensional cartesian coordinates, times and some metadata. A 3D
trajectory is a 2D trajectory (see TrajFromCoords) with the
addition of a z coordinate. trajr functions that expect a 2D
trajectory will work on a 3D trajectory by simply ignoring the z
dimension, so should only be used with care. A small number of functions
operate on 3D trajectories, and are prefixed by Traj3D. Existing
trajr functions that that do not deal with spatial data (e.g.
TrajDuration, TrajGetNCoords etc.) can safely be
used.
Traj3DFromCoords(
track,
xCol = 1,
yCol = 2,
zCol = 3,
timeCol = NULL,
fps = 50,
spatialUnits = "m",
timeUnits = "s"
)An object with class "Trajectory3D", which is a data.frame
with the following components:
X coordinates of trajectory points.
Y coordinates of trajectory points.
Time (in
timeUnits) for each point. if timeCol is specified, values
are track[,timeCol], otherwise values are calculated from
fps.
Relative frame/observation times, with
frame/observation 1 at time 0.
X and y coordinates represented as complex numbers, to simplify working with 2D segment angles. Note that the z dimension is not represented.
2-dimensional displacement vectors (represented as complex numbers) between each pair of consecutive points. Note that the z dimension is not represented.
data frame containing cartesian coordinates and optionally times for the points in the trajectory.
Name or index of the x column in track (default 1).
Name or index of the y column in track (default 2).
Name or index of the z column in track (default 3).
optional name or index of the column which contains coordinate times.
Frames per second - used to calculate relative coordinate times if
track does not contain a time column. Time intervals between
coordinate are assumed to be constant throught the entire track.
Abbreviation for the x, y and z units.
Abbreviation for the units that time is recorded in.
The coordinates are sometimes referred to as "relocations". Rows containing
NA coordinate or time values at the start or end of the trajectory are
discarded. NA coordinates or times in the middle of the trajectory
generate an error.
If timeCol is specified, track[,timeCol] is expected to contain
the time (in some numeric units) of each coordinate. Otherwise, times are
calculated for each point as (coord - 1) / fps where coord is
the index of the point; in other words, sampling at constant time intervals
is assumed. Time values require conversion if they are not numeric. It may be
possible to use `strptime` for this purpose, or TrajConvertTime
can be used to convert multiple field time values.
x and y must be square units. Longitude and latitude are not
suitable for use as x and y values, since in general, 1°
lat != 1° lon. To create a trajectory from positions in latitude and
longitude, it is first necessary to transform the positions to a suitable
spatial projection such as UTM (possibly by using spTransform from the
rgdal package).
Leading and trailing rows with NA coordinate values are discarded.
NA coordinate values within a trajectory generate an error.
Traj3DLength, Traj3DStepLengths,
Traj3DDistance, Traj3DStraightness,
Traj3DSmoothSG, Traj3DResampleTime,
Traj3DRediscretize, TrajFromCoords for creating
2-dimensional trajectories