smallest_circlesmallest_circleSmallestCircleSmallestCirclesmallest_circle（算子）

名称

smallest_circlesmallest_circleSmallestCircleSmallestCirclesmallest_circle — 区域的最小外接圆。

签名

描述

算子 smallest_circlesmallest_circleSmallestCircleSmallestCircleSmallestCirclesmallest_circle determines the smallest surrounding circle of a region, i.e., the circle with the smallest area of all circles containing the region. For this circle the center (RowRowRowRowrowrow,ColumnColumnColumnColumncolumncolumn) and the radius (RadiusRadiusRadiusRadiusradiusradius) are calculated. The operator is applied when, for example, the location and size of circular objects (e.g., coins) which, however, are not homogeneous inside or have broken edges due to bad segmentation, has to be determined. The output of the operator is selected in such a way that it can be used as input for the operators disp_circledisp_circleDispCircleDispCircleDispCircledisp_circle and gen_circlegen_circleGenCircleGenCircleGenCirclegen_circle。

In the documentation of this chapter (Regions / Features), you can find an image illustrating regions with varying outer and inner radii.

If several regions are passed in RegionsRegionsRegionsRegionsregionsregions corresponding tuples are returned as output parameter. In case of empty region all parameters have the value 0.0 if no other behavior was set (see set_systemset_systemSetSystemSetSystemSetSystemset_system).

注意

Internally, the calculation is based on the center coordinates of the region pixels. To take into account that pixels are not just infinitely small points but have a certain area, the calculated radius is enlarged by 0.5 before it is returned in RadiusRadiusRadiusRadiusradiusradius. This, in most cases, gives acceptable results. However, in the worst case (pixel diagonal) this enlargement is not sufficient. If one wants to ensure that the border of the input region completely lies within the circle, one had to enlarge the radius by instead of 0.5. Consequently, the value returned in RadiusRadiusRadiusRadiusradiusradius must be corrected by . However, this would also be only an upper bound, i.e., the circle with the corrected radius would be slightly too big in most cases.

执行信息

• 多线程类型：可重入（与非独占算子并行运行）。
• 多线程作用域：全局（可从任何线程调用）。
• 在元组级别上自动并行化。

参数

read_image(Image,'fabrik')
regiongrowing(Image,Regions,5,5,6,100)
select_shape(Regions,SelectedRegions,'area','and',100,2000)
smallest_circle(SelectedRegions,Row,Column,Radius)
gen_circle(Circles,Row,Column,Radius)
dev_display (Circles)

read_image(&Image,"fabrik");
regiongrowing(Image,&Regions,5,5,6.0,100);
select_shape(Regions,&SelectedRegions,"area","and",100.0,2000.0);
T_smallest_circle(SelectedRegions,&Row,&Column,&Radius);
T_gen_circle(&Circles,Row,Column,Radius);

read_image(Image,'fabrik')
regiongrowing(Image,Regions,5,5,6,100)
select_shape(Regions,SelectedRegions,'area','and',100,2000)
smallest_circle(SelectedRegions,Row,Column,Radius)
gen_circle(Circles,Row,Column,Radius)
dev_display (Circles)

read_image(Image,'fabrik')
regiongrowing(Image,Regions,5,5,6,100)
select_shape(Regions,SelectedRegions,'area','and',100,2000)
smallest_circle(SelectedRegions,Row,Column,Radius)
gen_circle(Circles,Row,Column,Radius)
dev_display (Circles)

read_image(Image,'fabrik')
regiongrowing(Image,Regions,5,5,6,100)
select_shape(Regions,SelectedRegions,'area','and',100,2000)
smallest_circle(SelectedRegions,Row,Column,Radius)
gen_circle(Circles,Row,Column,Radius)
dev_display (Circles)

复杂度

If F is the area of the region, then the mean runtime complexity is O(sqrt(F).

结果

算子 smallest_circlesmallest_circleSmallestCircleSmallestCircleSmallestCirclesmallest_circle 在输入不为空时返回值 2 (H_MSG_TRUE)。当输入为空（无可用输入区域）时，可设置行为通过算子 set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>)。当空区域（区域是空集）时，可设置行为通过算子 set_system('empty_region_result',<Result>)set_system("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)set_system("empty_region_result",<Result>)。如有必要，则抛出异常。

可能的前趋

thresholdthresholdThresholdThresholdThresholdthreshold, regiongrowingregiongrowingRegiongrowingRegiongrowingRegiongrowingregiongrowing, connectionconnectionConnectionConnectionConnectionconnection, runlength_featuresrunlength_featuresRunlengthFeaturesRunlengthFeaturesRunlengthFeaturesrunlength_features

可能的后继

gen_circlegen_circleGenCircleGenCircleGenCirclegen_circle, disp_circledisp_circleDispCircleDispCircleDispCircledisp_circle

替代

elliptic_axiselliptic_axisEllipticAxisEllipticAxisEllipticAxiselliptic_axis, smallest_rectangle1smallest_rectangle1SmallestRectangle1SmallestRectangle1SmallestRectangle1smallest_rectangle1, smallest_rectangle2smallest_rectangle2SmallestRectangle2SmallestRectangle2SmallestRectangle2smallest_rectangle2

另见

set_shapeset_shapeSetShapeSetShapeSetShapeset_shape, select_shapeselect_shapeSelectShapeSelectShapeSelectShapeselect_shape, inner_circleinner_circleInnerCircleInnerCircleInnerCircleinner_circle

模块

基础