get_contour_angle_xldget_contour_angle_xldGetContourAngleXldGetContourAngleXldGetContourAngleXldget_contour_angle_xld calculates for each point of the XLD
contour ContourContourContourContourcontourcontour the direction of its tangent. Two modes
for the output values can be chosen: By passing 'abs'"abs""abs""abs""abs""abs" for
AngleModeAngleModeAngleModeAngleModeangleModeangle_mode, the resulting angles are returned relative to
the horizontal axis as angles between 0 and
(counter-clockwise). By passing 'rel'"rel""rel""rel""rel""rel", the
angle difference to the previous contour point is
returned. In this case the range of values is between
and , where negative values indicate a right turn and
positive values indicate a left turn.
There are three different ways of calculating the tangent direction
(CalcModeCalcModeCalcModeCalcModecalcModecalc_mode) of the contour point i using the
contour points in the interval from
to
. By using 'range'"range""range""range""range""range",
the angle of the line segment between the first and last point of
the interval is used. For 'mean'"mean""mean""mean""mean""mean", the average of all
angles between consecutive points of the contour is used. Finally,
for 'regress'"regress""regress""regress""regress""regress", the direction of the regression line (the
least squares fit of a line to the contour points in the interval)
is used. LookaroundLookaroundLookaroundLookaroundlookaroundlookaround is a measure of how strongly the
contour is smoothed. The angles are returned in AnglesAnglesAnglesAnglesanglesangles
in radians.
Due to the interval given by LookaroundLookaroundLookaroundLookaroundlookaroundlookaround, the input contour
must have at least
points.
This minimum number of points is required so that the operator
always delivers reasonable output values for the different
parameter settings.