points_foerstner T_points_foerstner PointsFoerstner PointsFoerstner points_foerstner (Operator)
Name
points_foerstner T_points_foerstner PointsFoerstner PointsFoerstner points_foerstner
Signature
points_foerstner (Image SigmaGrad SigmaInt SigmaPoints ThreshInhom ThreshShape Smoothing EliminateDoublets RowJunctions ColumnJunctions CoRRJunctions CoRCJunctions CoCCJunctions RowArea ColumnArea CoRRArea CoRCArea CoCCArea
Herror T_points_foerstner (const Hobject Image SigmaGrad SigmaInt SigmaPoints ThreshInhom ThreshShape Smoothing EliminateDoublets RowJunctions ColumnJunctions CoRRJunctions CoRCJunctions CoCCJunctions RowArea ColumnArea CoRRArea CoRCArea CoCCArea
void PointsFoerstner (const HObject& Image SigmaGrad SigmaInt SigmaPoints ThreshInhom ThreshShape Smoothing EliminateDoublets RowJunctions ColumnJunctions CoRRJunctions CoRCJunctions CoCCJunctions RowArea ColumnArea CoRRArea CoRCArea CoCCArea
void HImage ::PointsFoerstner (const HTuple& SigmaGrad SigmaInt SigmaPoints ThreshInhom ThreshShape Smoothing EliminateDoublets RowJunctions ColumnJunctions CoRRJunctions CoRCJunctions CoCCJunctions RowArea ColumnArea CoRRArea CoRCArea CoCCArea
void HImage ::PointsFoerstner (double SigmaGrad SigmaInt SigmaPoints ThreshInhom ThreshShape Smoothing EliminateDoublets RowJunctions ColumnJunctions CoRRJunctions CoRCJunctions CoCCJunctions RowArea ColumnArea CoRRArea CoRCArea CoCCArea
void HImage ::PointsFoerstner (double SigmaGrad SigmaInt SigmaPoints ThreshInhom ThreshShape Smoothing EliminateDoublets RowJunctions ColumnJunctions CoRRJunctions CoRCJunctions CoCCJunctions RowArea ColumnArea CoRRArea CoRCArea CoCCArea
void HImage ::PointsFoerstner (double SigmaGrad SigmaInt SigmaPoints ThreshInhom ThreshShape Smoothing EliminateDoublets RowJunctions ColumnJunctions CoRRJunctions CoRCJunctions CoCCJunctions RowArea ColumnArea CoRRArea CoRCArea CoCCArea
(
Windows only)
static void HOperatorSet .PointsFoerstner (HObject image HTuple sigmaGrad HTuple sigmaInt HTuple sigmaPoints HTuple threshInhom HTuple threshShape HTuple smoothing HTuple eliminateDoublets HTuple rowJunctions HTuple columnJunctions HTuple coRRJunctions HTuple coRCJunctions HTuple coCCJunctions HTuple rowArea HTuple columnArea HTuple coRRArea HTuple coRCArea HTuple coCCArea
void HImage .PointsFoerstner (HTuple sigmaGrad HTuple sigmaInt HTuple sigmaPoints HTuple threshInhom threshShape smoothing eliminateDoublets HTuple rowJunctions HTuple columnJunctions HTuple coRRJunctions HTuple coRCJunctions HTuple coCCJunctions HTuple rowArea HTuple columnArea HTuple coRRArea HTuple coRCArea HTuple coCCArea
void HImage .PointsFoerstner (double sigmaGrad sigmaInt sigmaPoints threshInhom threshShape smoothing eliminateDoublets HTuple rowJunctions HTuple columnJunctions HTuple coRRJunctions HTuple coRCJunctions HTuple coCCJunctions HTuple rowArea HTuple columnArea HTuple coRRArea HTuple coRCArea HTuple coCCArea
def points_foerstner (image sigma_grad sigma_int sigma_points thresh_inhom thresh_shape smoothing eliminate_doublets
Description
points_foerstner points_foerstner PointsFoerstner PointsFoerstner points_foerstner
The point extraction takes place in two steps: In the first step the point
regions, i.e., the inhomogeneous, isotropic regions, are extracted from the
image. To do so, the smoothed matrix
Smoothing Smoothing Smoothing smoothing smoothing 'gauss' "gauss" "gauss" "gauss" "gauss" SigmaGrad SigmaGrad SigmaGrad sigmaGrad sigma_grad SigmaInt SigmaInt SigmaInt sigmaInt sigma_int Smoothing Smoothing Smoothing smoothing smoothing 'mean' "mean" "mean" "mean" "mean" SigmaGrad SigmaGrad SigmaGrad sigmaGrad sigma_grad SigmaInt SigmaInt SigmaInt sigmaInt sigma_int SigmaInt SigmaInt SigmaInt sigmaInt sigma_int
inhomogeneity = Trace(M)
is the degree of inhomogeneity in the image and
ThreshInhom ThreshInhom ThreshInhom threshInhom thresh_inhom ThreshShape ThreshShape ThreshShape threshShape thresh_shape
In the second step, two optimization functions are calculated for the
resulting points. Essentially, these optimization functions average for each
point the distances to the edge directions (for junction points) and the
gradient directions (for area points) within an observation window around
the point. If Smoothing Smoothing Smoothing smoothing smoothing 'gauss' "gauss" "gauss" "gauss" "gauss" SigmaPoints SigmaPoints SigmaPoints sigmaPoints sigma_points Smoothing Smoothing Smoothing smoothing smoothing 'mean' "mean" "mean" "mean" "mean" SigmaPoints SigmaPoints SigmaPoints sigmaPoints sigma_points SigmaPoints SigmaPoints SigmaPoints sigmaPoints sigma_points RowJunctions RowJunctions RowJunctions rowJunctions row_junctions ColumnJunctions ColumnJunctions ColumnJunctions columnJunctions column_junctions RowArea RowArea RowArea rowArea row_area ColumnArea ColumnArea ColumnArea columnArea column_area
In addition to their position, for each extracted point the elements
CoRRJunctions CoRRJunctions CoRRJunctions coRRJunctions co_rrjunctions CoRCJunctions CoRCJunctions CoRCJunctions coRCJunctions co_rcjunctions CoCCJunctions CoCCJunctions CoCCJunctions coCCJunctions co_ccjunctions CoRRArea CoRRArea CoRRArea coRRArea co_rrarea CoRCArea CoRCArea CoRCArea coRCArea co_rcarea CoCCArea CoCCArea CoCCArea coCCArea co_ccarea intensity intensity Intensity Intensity intensity plane_deviation plane_deviation PlaneDeviation PlaneDeviation plane_deviation points_foerstner_ellipses.hdev.
It lies in the nature of this operator that corners often result in two
distinct points: One junction point, where the edges of the corner actually
meet, and one area point inside the corner. Such doublets will be eliminated
automatically, if EliminateDoublets EliminateDoublets EliminateDoublets eliminateDoublets eliminate_doublets 'true' "true" "true" "true" "true" EliminateDoublets EliminateDoublets EliminateDoublets eliminateDoublets eliminate_doublets 'false' "false" "false" "false" "false"
Attention
Note that only odd values for SigmaInt SigmaInt SigmaInt sigmaInt sigma_int SigmaPoints SigmaPoints SigmaPoints sigmaPoints sigma_points Smoothing Smoothing Smoothing smoothing smoothing 'mean' "mean" "mean" "mean" "mean"
points_foerstner points_foerstner PointsFoerstner PointsFoerstner points_foerstner Smoothing Smoothing Smoothing smoothing smoothing 'gauss' "gauss" "gauss" "gauss" "gauss" 'sse2_enable' "sse2_enable" "sse2_enable" "sse2_enable" "sse2_enable" 'true' "true" "true" "true" "true" RowJunctions RowJunctions RowJunctions rowJunctions row_junctions ColumnJunctions ColumnJunctions ColumnJunctions columnJunctions column_junctions 'sse2_enable' "sse2_enable" "sse2_enable" "sse2_enable" "sse2_enable" 'false' "false" "false" "false" "false" set_system set_system SetSystem SetSystem set_system points_foerstner points_foerstner PointsFoerstner PointsFoerstner points_foerstner points_foerstner points_foerstner PointsFoerstner PointsFoerstner points_foerstner 'sse2_enable' "sse2_enable" "sse2_enable" "sse2_enable" "sse2_enable" 'true' "true" "true" "true" "true"
Note that filter operators may return unexpected results if
an image with a reduced domain is used as input. Please refer to the
chapter Filters .
Execution Information
Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Automatically parallelized on internal data level.
Parameters
Image Image Image image image (multichannel-)image → object HImage HObject HObject Hobject (byte / uint2 / real)
Input image.
SigmaGrad SigmaGrad SigmaGrad sigmaGrad sigma_grad number → HTuple Union[float, int] HTuple Htuple (real / integer) (double / int / long) (double / Hlong) (double / Hlong)
Amount of smoothing used for the calculation of the
gradient. If Smoothing Smoothing Smoothing smoothing smoothing SigmaGrad SigmaGrad SigmaGrad sigmaGrad sigma_grad
Default:
1.0
Suggested values:
0.7, 0.8, 0.9, 1.0, 1.2, 1.5, 2.0, 3.0
Value range:
0.0
≤
SigmaGrad
SigmaGrad
SigmaGrad
sigmaGrad
sigma_grad
Recommended increment:
0.1
SigmaInt SigmaInt SigmaInt sigmaInt sigma_int number → HTuple Union[float, int] HTuple Htuple (real / integer) (double / int / long) (double / Hlong) (double / Hlong)
Amount of smoothing used for the integration of the
gradients.
Default:
2.0
Suggested values:
0.7, 0.8, 0.9, 1.0, 1.2, 1.5, 2.0, 3.0
Recommended increment:
0.1
Restriction:
SigmaInt > 0
SigmaPoints SigmaPoints SigmaPoints sigmaPoints sigma_points number → HTuple Union[float, int] HTuple Htuple (real / integer) (double / int / long) (double / Hlong) (double / Hlong)
Amount of smoothing used in the optimization
functions.
Default:
3.0
Suggested values:
0.7, 0.8, 0.9, 1.0, 1.2, 1.5, 2.0, 3.0
Recommended increment:
0.1
Restriction:
SigmaPoints >= SigmaInt && SigmaPoints > 0.6
ThreshInhom ThreshInhom ThreshInhom threshInhom thresh_inhom number → HTuple Union[float, int] HTuple Htuple (real / integer) (double / int / long) (double / Hlong) (double / Hlong)
Threshold for the segmentation of inhomogeneous image
areas.
Default:
200
Suggested values:
50, 100, 200, 500, 1000
Value range:
0.0
≤
ThreshInhom
ThreshInhom
ThreshInhom
threshInhom
thresh_inhom
ThreshShape ThreshShape ThreshShape threshShape thresh_shape real → HTuple float HTuple Htuple (real) (double ) (double ) (double )
Threshold for the segmentation of point areas.
Default:
0.3
Suggested values:
0.1, 0.2, 0.3, 0.4, 0.5, 0.7
Value range:
0.01
≤
ThreshShape
ThreshShape
ThreshShape
threshShape
thresh_shape
≤
1
Minimum increment:
0.01
Recommended increment:
0.1
Smoothing Smoothing Smoothing smoothing smoothing string → HTuple str HTuple Htuple (string) (string ) (HString ) (char* )
Used smoothing method.
Default:
'gauss'
"gauss"
"gauss"
"gauss"
"gauss"
List of values:
'gauss' "gauss" "gauss" "gauss" "gauss" , 'mean' "mean" "mean" "mean" "mean"
EliminateDoublets EliminateDoublets EliminateDoublets eliminateDoublets eliminate_doublets string → HTuple str HTuple Htuple (string) (string ) (HString ) (char* )
Elimination of multiply detected points.
Default:
'false'
"false"
"false"
"false"
"false"
List of values:
'false' "false" "false" "false" "false" , 'true' "true" "true" "true" "true"
RowJunctions RowJunctions RowJunctions rowJunctions row_junctions point.y-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Row coordinates of the detected junction points.
ColumnJunctions ColumnJunctions ColumnJunctions columnJunctions column_junctions point.x-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Column coordinates of the detected junction points.
CoRRJunctions CoRRJunctions CoRRJunctions coRRJunctions co_rrjunctions number-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Row part of the covariance matrix of the detected
junction points.
CoRCJunctions CoRCJunctions CoRCJunctions coRCJunctions co_rcjunctions number-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Mixed part of the covariance matrix of the detected
junction points.
CoCCJunctions CoCCJunctions CoCCJunctions coCCJunctions co_ccjunctions number-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Column part of the covariance matrix of the detected
junction points.
RowArea RowArea RowArea rowArea row_area point.y-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Row coordinates of the detected area points.
ColumnArea ColumnArea ColumnArea columnArea column_area point.x-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Column coordinates of the detected area points.
CoRRArea CoRRArea CoRRArea coRRArea co_rrarea number-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Row part of the covariance matrix of the detected
area points.
CoRCArea CoRCArea CoRCArea coRCArea co_rcarea number-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Mixed part of the covariance matrix of the detected
area points.
CoCCArea CoCCArea CoCCArea coCCArea co_ccarea number-array → HTuple Sequence[float] HTuple Htuple (real) (double ) (double ) (double )
Column part of the covariance matrix of the detected
area points.
Result
points_foerstner points_foerstner PointsFoerstner PointsFoerstner points_foerstner 2 (
H_MSG_TRUE )
if all parameters are correct
and no error occurs during the execution. If the input is empty the
behavior can be set via
set_system('no_object_result',<Result>) set_system("no_object_result",<Result>) SetSystem("no_object_result",<Result>) SetSystem("no_object_result",<Result>) set_system("no_object_result",<Result>)
Possible Successors
gen_cross_contour_xld gen_cross_contour_xld GenCrossContourXld GenCrossContourXld gen_cross_contour_xld disp_cross disp_cross DispCross DispCross disp_cross
Alternatives
points_harris points_harris PointsHarris PointsHarris points_harris points_lepetit points_lepetit PointsLepetit PointsLepetit points_lepetit points_harris_binomial points_harris_binomial PointsHarrisBinomial PointsHarrisBinomial points_harris_binomial
References
W. Förstner, E. Gülch: “A Fast Operator for Detection and Precise
Location of Distinct Points, Corners and Circular features”. In
Proceedings of the Intercommission Conference on Fast Processing of
Photogrametric Data, Interlaken, pp. 281-305, 1987.
Module
Foundation