gen_measure_arcT_gen_measure_arcGenMeasureArcGenMeasureArcgen_measure_arc (Operator)

Name

gen_measure_arcT_gen_measure_arcGenMeasureArcGenMeasureArcgen_measure_arc — Prepare the extraction of straight edges perpendicular to an annular arc.

Signature

gen_measure_arc( : : CenterRow, CenterCol, Radius, AngleStart, AngleExtent, AnnulusRadius, Width, Height, Interpolation : MeasureHandle)

Description

gen_measure_arcgen_measure_arcGenMeasureArcGenMeasureArcgen_measure_arc prepares the extraction of straight edges which lie perpendicular to an annular arc. Here, annular arc denotes a circular arc with an associated width. The center of the arc is passed in the parameters CenterRowCenterRowCenterRowcenterRowcenter_row and CenterColCenterColCenterColcenterColcenter_col, its radius in RadiusRadiusRadiusradiusradius, the starting angle in AngleStartAngleStartAngleStartangleStartangle_start, and its angular extent relative to the starting angle in AngleExtentAngleExtentAngleExtentangleExtentangle_extent. If AngleExtentAngleExtentAngleExtentangleExtentangle_extent > 0, an arc with counterclockwise orientation is generated, otherwise an arc with clockwise orientation. The radius of the annular arc, i.e., half its width, is determined by AnnulusRadiusAnnulusRadiusAnnulusRadiusannulusRadiusannulus_radius.

For an explanation of the concept of 1D measuring see the introduction of chapter 1D Measuring.

The edge extraction algorithm is described in the documentation of the operator measure_posmeasure_posMeasurePosMeasurePosmeasure_pos. As discussed there, different types of interpolation can be used for the calculation of the one-dimensional gray value profile. For InterpolationInterpolationInterpolationinterpolationinterpolation = 'nearest_neighbor'"nearest_neighbor""nearest_neighbor""nearest_neighbor""nearest_neighbor", the gray values in the measurement are obtained from the gray values of the closest pixel, i.e., by constant interpolation. For InterpolationInterpolationInterpolationinterpolationinterpolation = 'bilinear'"bilinear""bilinear""bilinear""bilinear", bilinear interpolation is used, while for InterpolationInterpolationInterpolationinterpolationinterpolation = 'bicubic'"bicubic""bicubic""bicubic""bicubic", bicubic interpolation is used.

To perform the actual measurement at optimal speed, all computations that can be used for multiple measurements are already performed in the operator gen_measure_arcgen_measure_arcGenMeasureArcGenMeasureArcgen_measure_arc. For this, an optimized data structure, a so-called measure object, is constructed and returned in MeasureHandleMeasureHandleMeasureHandlemeasureHandlemeasure_handle. The size of the images in which measurements will be performed must be specified in the parameters WidthWidthWidthwidthwidth and HeightHeightHeightheightheight.

The system parameter 'int_zooming'"int_zooming""int_zooming""int_zooming""int_zooming" (see set_systemset_systemSetSystemSetSystemset_system) affects the accuracy and speed of the calculations used to construct the measure object. If 'int_zooming'"int_zooming""int_zooming""int_zooming""int_zooming" is set to 'true'"true""true""true""true", the internal calculations are performed using fixed point arithmetic, leading to much shorter execution times. However, the geometric accuracy is slightly lower in this mode. If 'int_zooming'"int_zooming""int_zooming""int_zooming""int_zooming" is set to 'false'"false""false""false""false", the internal calculations are performed using floating point arithmetic, leading to the maximum geometric accuracy, but also to significantly increased execution times.

Attention

Note that when using bilinear or bicubic interpolation, not only the measurement rectangle but additionally the margin around the rectangle must fit into the image. The width of the margin (in all four directions) must be at least one pixel for bilinear interpolation and two pixels for bicubic interpolation. For projection lines that do not fulfill this condition, no gray value is computed. Thus, no edge can be extracted at these positions.

Please also note that the center coordinates of the arc are rounded internally, so that the center lies on the pixel grid. This is done to ensure consistency.

Execution Information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Processed without parallelization.

This operator returns a handle. Note that the state of an instance of this handle type may be changed by specific operators even though the handle is used as an input parameter by those operators.

Parameters

CenterRowCenterRowCenterRowcenterRowcenter_row (input_control) point.y → (real / integer)

Row coordinate of the center of the arc.

Default: 100.0

Suggested values: 10.0, 20.0, 50.0, 100.0, 200.0, 300.0, 400.0, 500.0

Value range: 0.0 ≤ CenterRow CenterRow CenterRow centerRow center_row (lin)

Minimum increment: 1.0

Recommended increment: 10.0

CenterColCenterColCenterColcenterColcenter_col (input_control) point.x → (real / integer)

Column coordinate of the center of the arc.

Default: 100.0

Suggested values: 10.0, 20.0, 50.0, 100.0, 200.0, 300.0, 400.0, 500.0

Value range: 0.0 ≤ CenterCol CenterCol CenterCol centerCol center_col (lin)

Minimum increment: 1.0

Recommended increment: 10.0

RadiusRadiusRadiusradiusradius (input_control) number → (real / integer)

Radius of the arc.

Default: 50.0

Suggested values: 10.0, 20.0, 50.0, 100.0, 200.0, 300.0, 400.0, 500.0

Value range: Radius Radius Radius radius radius (lin)

Minimum increment: 1.0

Recommended increment: 10.0

Restriction: AnnulusRadius <= Radius

AngleStartAngleStartAngleStartangleStartangle_start (input_control) angle.rad → (real / integer)

Start angle of the arc in radians.

Default: 0.0

Suggested values: -3.14159, -2.35619, -1.57080, -0.78540, 0.0, 0.78540, 1.57080, 2.35619, 3.14159

Value range: -3.14159 ≤ AngleStart AngleStart AngleStart angleStart angle_start ≤ 3.14159 (lin)

Minimum increment: 0.03142

Recommended increment: 0.31416

AngleExtentAngleExtentAngleExtentangleExtentangle_extent (input_control) angle.rad → (real / integer)

Angular extent of the arc in radians.

Default: 6.28318

Suggested values: -6.28318, -5.49779, -4.71239, -3.92699, -3.14159, -2.35619, -1.57080, -0.78540, 0.78540, 1.57080, 2.35619, 3.14159, 3.92699, 4.71239, 5.49779, 6.28318

Value range: -6.28318 ≤ AngleExtent AngleExtent AngleExtent angleExtent angle_extent ≤ 6.28318 (lin)

Minimum increment: 0.03142

Recommended increment: 0.31416

AnnulusRadiusAnnulusRadiusAnnulusRadiusannulusRadiusannulus_radius (input_control) number → (real / integer)

Radius (half width) of the annulus.

Default: 10.0

Suggested values: 10.0, 20.0, 50.0, 100.0, 200.0, 300.0, 400.0, 500.0

Value range: AnnulusRadius AnnulusRadius AnnulusRadius annulusRadius annulus_radius (lin)

Minimum increment: 1.0

Recommended increment: 10.0

Restriction: AnnulusRadius > 0

WidthWidthWidthwidthwidth (input_control) extent.x → (integer)

Width of the image to be processed subsequently.

Default: 512

Suggested values: 128, 160, 192, 256, 320, 384, 512, 640, 768

Value range: 0 ≤ Width Width Width width width (lin)

Minimum increment: 1

Recommended increment: 16

HeightHeightHeightheightheight (input_control) extent.y → (integer)

Height of the image to be processed subsequently.

Default: 512

Suggested values: 120, 128, 144, 240, 256, 288, 480, 512, 576

Value range: 0 ≤ Height Height Height height height (lin)

Minimum increment: 1

Recommended increment: 16

InterpolationInterpolationInterpolationinterpolationinterpolation (input_control) string → (string)

Type of interpolation to be used.

Default: 'nearest_neighbor' "nearest_neighbor" "nearest_neighbor" "nearest_neighbor" "nearest_neighbor"

List of values: 'bicubic'"bicubic""bicubic""bicubic""bicubic", 'bilinear'"bilinear""bilinear""bilinear""bilinear", 'nearest_neighbor'"nearest_neighbor""nearest_neighbor""nearest_neighbor""nearest_neighbor"

MeasureHandleMeasureHandleMeasureHandlemeasureHandlemeasure_handle (output_control) measure → (handle)

Measure object handle.

Result

If the parameter values are correct, the operator gen_measure_arcgen_measure_arcGenMeasureArcGenMeasureArcgen_measure_arc returns the value 2 ( H_MSG_TRUE) . Otherwise an exception is raised.