gen_measure

Herror ::gen_measure_arc ( const HTuple &CenterRow, const HTuple &CenterCol, const HTuple &Radius, const HTuple &AngleStart, const HTuple &AngleExtent, const HTuple &AnnulusRadius, const HTuple &Width, const HTuple &Height, const HTuple &Interpolation, long *MeasureHandle )

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

::gen_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 CenterRow and CenterCol, its radius in Radius, the starting angle in AngleStart, and its angular extent relative to the starting angle in AngleExtent. If AngleExtent > 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 AnnulusRadius.

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

With ::gen_measure_rectangle2, all computations which can be used for multiple measurements are removed from the actual measurement. To effect this, an optimized data structure, a so-called measure object, is constructed and returned in MeasureHandle. In order to perform the measurement at the optimum speed, the size of the images for which subsequent measurements will be made must already be specified in ::gen_measure_rectangle2 with the parameters Width and Height. This technique increases the speed of the actual measurement significantly.

Parameters

`CenterRow` (input_control)	point.y `->` HTuple.double / long
Row coordinate of the center of the arc.
Default value: 100.0
Suggested values: 10.0, 20.0, 50.0, 100.0, 200.0, 300.0, 400.0, 500.0
Typical range of values: `0.0 <= CenterRow <= 511.0` (lin)
Minimum increment: 1.0
Recommended increment: 10.0

`CenterCol` (input_control)	point.x `->` HTuple.double / long
Column coordinate of the center of the arc.
Default value: 100.0
Suggested values: 10.0, 20.0, 50.0, 100.0, 200.0, 300.0, 400.0, 500.0
Typical range of values: `0.0 <= CenterCol <= 511.0` (lin)
Minimum increment: 1.0
Recommended increment: 10.0

`Radius` (input_control)	number `->` HTuple.double / long
Radius of the arc.
Default value: 50.0
Suggested values: 10.0, 20.0, 50.0, 100.0, 200.0, 300.0, 400.0, 500.0
Typical range of values: `0.0 <= Radius <= 511.0` (lin)
Minimum increment: 1.0
Recommended increment: 10.0

`AngleStart` (input_control)	angle.rad `->` HTuple.double / long
Start angle of the arc in radians.
Default value: 0.0
Suggested values: -3.14159265359, -2.35619449019, -1.5707963268, -0.785398163398, 0.0, 0.785398163398, 1.5707963268, 2.35619449019, 3.14159265359
Typical range of values: `-3.14159265359 <= AngleStart <= 3.14159265359` (lin)
Minimum increment: 0.0314159265359
Recommended increment: 0.314159265359

`AngleExtent` (input_control)	angle.rad `->` HTuple.double / long
Angular extent of the arc in radians.
Default value: 6.28318530718
Suggested values: -6.28318530718, -5.49778714378, -4.71238898038, -3.926990817, -3.14159265359, -2.35619449019, -1.5707963268, -0.785398163398, 0.785398163398, 1.5707963268, 2.35619449019, 3.14159265359, 3.926990817, 4.71238898038, 5.49778714378, 6.28318530718
Typical range of values: `-6.28318530718 <= AngleExtent <= 6.28318530718` (lin)
Minimum increment: 0.0314159265359
Recommended increment: 0.314159265359
Restriction: `AngleExtent != 0.0`

`AnnulusRadius` (input_control)	number `->` HTuple.double / long
Radius (half width) of the the annulus.
Default value: 10.0
Suggested values: 10.0, 20.0, 50.0, 100.0, 200.0, 300.0, 400.0, 500.0
Typical range of values: `0.0 <= AnnulusRadius <= 511.0` (lin)
Minimum increment: 1.0
Recommended increment: 10.0
Restriction: `AnnulusRadius <= Radius`

`Width` (input_control)	extent.x `->` HTuple.long
Width of the image to be processed subsequently.
Default value: 512
Suggested values: 128, 160, 192, 256, 320, 384, 512, 640, 768
Typical range of values: `0 <= Width <= 1024` (lin)
Minimum increment: 1
Recommended increment: 16

`Height` (input_control)	extent.y `->` HTuple.long
Height of the image to be processed subsequently.
Default value: 512
Suggested values: 120, 128, 144, 240, 256, 288, 480, 512, 576
Typical range of values: `0 <= Height <= 1024` (lin)
Minimum increment: 1
Recommended increment: 16

`Interpolation` (input_control)	string `->` HTuple.char *
Type of interpolation to be used.
Default value: 'nearest_neighbor'
List of values: 'nearest_neighbor', 'bilinear', 'bicubic'

`MeasureHandle` (output_control)	measure_id `->` long *
Measure object handle.

Result

If the parameter values are correct, the operator ::gen_measure_arc returns the value H_MSG_TRUE. Otherwise an exception handling is raised.

Possible Predecessors

::draw_circle

Possible Successors

::measure_pos, ::measure_pairs

Alternatives

::edges_sub_pix

Module

Sub-pixel operators