問題提出：求下圖中楔形缺口到圓心的最短距離。

【涉及知識點講解】

一、Region特征算子

在圖形窗口中用鼠標單擊選中某個Region，然後點擊菜單欄的“打開特征檢測”圖標，就可以看到當前Region的所有特征了。

由特征檢測頁面可知，Region的特征很多，如何知道用什麽算子可以獲得這些特征呢？

① 鼠標放在特征上懸停。

② region_features

二、形態學算子（以下面四個為例）

dilation_circle

erosion_circle

opening_rectangle1

closing_rectangle1

拓展閱讀：https://www.cnblogs.com/xh6300/p/6397289.html

三、tuple_concat和tuple_length、tuple_min

tuple叫做元組，類似於C#中的ArrayList。

a := 3

a := [a,4]

tuple_concat (a, 5, Concat)

a := [a,5]

tuple_length (Concat, Length)

len := |a|

tuple_min (a, Min)

minValue := min(a)

https://www.cnblogs.com/xh6300/p/6117688.html

四、完整代碼

*方法1：逐次逼近法

dev_set_draw (‘margin‘)

read_image (Image, ‘circle.jpg‘)

threshold (Image, Region, 0, 80)

opening_circle (Region, Region, 3.5)

smallest_circle (Region, Row, Column, Radius)

*Row, Column即是圓心坐標

gen_circle (Circle, Row, Column, Radius)

gen_cross_contour_xld (Cross, Row, Column, 6, 0.785398)

difference (Circle, Region, RegionResult)

*去掉細窄邊緣

opening_circle (RegionResult, RegionResult, 3.5)

*求最小外接圓直徑

diameter_region (RegionResult, Row1, Column1, Row2, Column2, Diameter)

gap := Radius - Diameter

*設置缺省值

realGap := gap

for i := gap to Radius by 1

gen_circle (Circle1, Row, Column, i)

intersection (Circle1, RegionResult, RegionIntersection)

area_center (RegionIntersection, Area, Row3, Column3)

if (Area > 0)

realGap := i

break

endif

endfor

dev_display (Image)

disp_message (3600,‘MinDist1：‘ + realGap, ‘image‘, Row, Column, ‘black‘, ‘true‘)

*方法2：distance_pr

distance_pr (RegionResult, Row, Column, DistanceMin, DistanceMax)

disp_message (3600,‘DistanceMin: ‘ + DistanceMin, ‘image‘, Row, Column, ‘black‘, ‘true‘)

dev_display (Image)

*方法3：遍歷點坐標,求最小距離

get_region_points (RegionResult, Rows, Columns)

Distances := []

for i := 0 to |Rows|-1 by 5

distance_pp (Row, Column, Rows[i], Columns[i], Distance)

Distances := [Distances , Distance]

endfor

tuple_min (Distances, Min)

disp_message (3600,‘MinDist1：‘ + realGap, ‘image‘, Row, Column, ‘black‘, ‘true‘)

disp_message (3600,‘DistanceMin: ‘ + DistanceMin, ‘image‘, Row+20, Column, ‘black‘, ‘true‘)

disp_message (3600,‘Min: ‘ + Min, ‘image‘, Row+40, Column, ‘black‘, ‘true‘)

Region特征算子與形態學運算——第3講