Region特征算子与形态学运算——第3讲

 

问题提出：求下图中楔形缺口到圆心的最短距离。

 

【涉及知识点讲解】

 

1、Region特征算子

 

在图形窗口中用鼠标单击选中某个Region，而后点击菜单栏的“打开特征检测”图标，就能够看到当前Region的全部特征了。

 

 

 

由特征检测页面可知，Region的特征不少，如何知道用什么算子能够得到这些特征呢？

 

① 鼠标放在特征上悬停。

 

② region_features

 

 

2、形态学算子（如下面四个为例）

 

dilation_circle

erosion_circle

opening_rectangle1

closing_rectangle1

 

拓展阅读：http://www.javashuo.com/article/p-ayjsikwe-eb.html

 

 

3、tuple_concat和tuple_length、tuple_min

 

tuple叫作元组，相似于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)

 

http://www.javashuo.com/article/p-rctchlvn-hw.html

 

 

4、完整代码

 

*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便是圆心坐标

gen_circle (Circle, Row, Column, Radius)

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

 

difference (Circle, Region, RegionResult)

*去掉细窄边缘

opening_circle (RegionResult, RegionResult, 3.5)

 

*求最小外接圆直径

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

gap := Radius - Diameter

*设置缺省值

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：遍历点坐标,求最小距离

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')