halcon极坐标变换角度设置问题

在别的网站看到一个案例：需要识别环状物体上的字符（OCR），要用到极坐标变换。

 按照最简单的模式，原始检测方案如下：

 read_image (Image, 'H:/学习笔记/halcon笔记/1.jpg')
    *获取图片尺寸，极坐标变换成原始图片大小
    get_image_size (Image, Width, Height)
    *获取圆环物体区域（包含字符），抠图
    threshold (Image, Region, 0, 100)
    connection (Region, ConnectedRegions)
    select_shape_std (ConnectedRegions, SelectedRegions, 'max_area', 70)
    fill_up_shape (SelectedRegions, RegionFillUp, 'area', 1, 10000)  
    reduce_domain (Image, RegionFillUp, ImageReduced)
      
    *求外圆圆心，半径
    gen_contour_region_xld (RegionFillUp, OuterCont, 'border')
    fit_circle_contour_xld (OuterCont, 'algebraic', -1, 0, 0, 3, 2, Row, Column, Radius, StartPhi, EndPhi, PointOrder)
    *求内圆圆心，半径
    fill_up (RegionFillUp, RegionFillUp1)
    difference (RegionFillUp1, RegionFillUp, RegionDifference)
    gen_contour_region_xld (RegionDifference, InnerCont, 'border')
    fit_circle_contour_xld (InnerCont, 'algebraic', -1, 0, 0, 3, 2, Row1, Column1, Radius1, StartPhi1, EndPhi1, PointOrder1)
    *极坐标变换
    polar_trans_image_ext (ImageReduced, PolarTransImage, Row, Column, 0, rad(360), Radius, Radius1, Width, Height, 'nearest_neighbor')
    *
    mirror_image (PolarTransImage, ImageMirror1, 'column')
    *下一步：OCR字符识别

但是这个方案有一个问题：变换的初始角度默认为0，最终角度默认为360度；如果不特别设置角度，变换后的图片中，字符可能不是连续的（被切割为两部分）；如果想完整识别字符，则需要字符不被切割分开。

最终呈现的效果如下：

优化方案：

重新设置极坐标变换的起始、终止角度：01、求字符区域的外接旋转矩形，求矩形的四个顶点。02、矩形同一边的2个顶点与物体外接圆圆心连线，计算线线之间夹角。03、以夹角作为起始角度，360+夹角作为终止角度。

以下为优化后的代码：

    read_image (Image, 'H:/BEGINNER/学习笔记1.jpg')
    *获取图片尺寸，极坐标变换成原始图片大小
    get_image_size (Image, Width, Height)
    *获取圆环物体区域（包含字符），抠图
    threshold (Image, Region, 0, 100)
    connection (Region, ConnectedRegions)
    select_shape_std (ConnectedRegions, SelectedRegions, 'max_area', 70)
    fill_up_shape (SelectedRegions, RegionFillUp, 'area', 1, 10000)  
    reduce_domain (Image, RegionFillUp, ImageReduced)
      
    *求外圆圆心，半径
    gen_contour_region_xld (RegionFillUp, OuterCont, 'border')
    fit_circle_contour_xld (OuterCont, 'algebraic', -1, 0, 0, 3, 2, Row, Column, Radius, StartPhi, EndPhi, PointOrder)
    *求内圆圆心，半径
    fill_up (RegionFillUp, RegionFillUp1)
    difference (RegionFillUp1, RegionFillUp, RegionDifference)
    gen_contour_region_xld (RegionDifference, InnerCont, 'border')
    fit_circle_contour_xld (InnerCont, 'algebraic', -1, 0, 0, 3, 2, Row1, Column1, Radius1, StartPhi1, EndPhi1, PointOrder1)
   
   *抠出字符区域，求此区域的角度
    threshold (ImageReduced, Region1, 100, 255)
    connection (Region1, ConnectedRegions1)
    select_shape (ConnectedRegions1, SelectedRegions1, 'width', 'and', 6, 12)
    select_shape (SelectedRegions1, SelectedRegions2, 'area', 'and', 16, 99999)
    closing_rectangle1 (SelectedRegions2, RegionClosing, 100,100)
    union1 (RegionClosing, RegionUnion)
    *区域转化为旋转矩形
    shape_trans (RegionUnion, RegionTrans, 'rectangle2')
    *得到外接旋转矩形的坐标，半边长
    smallest_rectangle2 (RegionTrans, Row2, Column2, Phi, Length1, Length2)
    dev_set_draw ('margin')
    *求矩形的四个顶点坐标
    if(abs(deg(Phi))>45)
        Phi:=rad(deg(Phi)-90*(Phi/abs(Phi)))
        Tmp:=Length1
        Length1:=Length2
        Length2:=Tmp
    endif
    tuple_sin (Phi, Sin)
    tuple_cos (Phi, Cos)
    *左上角
    TopLeft_X := -Length1*Cos - Length2*Sin
    TopLeft_Y := -Length1*Sin + Length2*Cos
    TopLeft_Row := Row2 - TopLeft_Y 
    TopLeft_Col := Column2 + TopLeft_X 
    gen_cross_contour_xld (Cross1, TopLeft_Row, TopLeft_Col, 30, 0.785398)
    *右上角
    TopRight_X := Length1*Cos - Length2*Sin
    TopRight_Y := Length1*Sin + Length2*Cos
    TopRight_Row := Row2 - TopRight_Y 
    TopRight_Col := Column2 + TopRight_X 
    gen_cross_contour_xld (Cross2, TopRight_Row, TopRight_Col, 30, 0.785398)
    *右下角
    LowerRight_X := Length1*Cos + Length2*Sin
    LowerRight_Y := Length1*Sin - Length2*Cos
    LowerRight_Row := Row2 - LowerRight_Y 
    LowerRight_Col := Column2 + LowerRight_X 
    gen_cross_contour_xld (Cross3, LowerRight_Row, LowerRight_Col, 30, 0.785398)
    *左下角
    LowerLeft_X := -Length1*Cos + Length2*Sin
    LowerLeft_Y := -Length1*Sin - Length2*Cos
    LowerLeft_Row := Row2 - LowerLeft_Y 
    LowerLeft_Col := Column2 + LowerLeft_X 
    gen_cross_contour_xld (Cross4, LowerLeft_Row, LowerLeft_Col, 30, 0.785398)
    *查看夹角效果   
    *dev_set_color ('blue')
    *gen_region_line (RegionLine1, Row, Column, TopRight_Row, TopRight_Col)
    *gen_region_line (RegionLine2, Row, Column, LowerRight_Row, LowerRight_Col)
   
    *得到四个顶点坐标后，取左（右）上左（右）下点，分别与大圆的圆心连线，求线线夹角
    angle_ll (Row, Column, TopRight_Row, TopRight_Col, Row, Column, LowerRight_Row, LowerRight_Col, Angle)
    tuple_deg (Angle, Deg)
   
    *极坐标变换
    polar_trans_image_ext (ImageReduced, PolarTransImage, Row, Column, rad(Deg), rad(360+Deg), Radius, Radius1, Width, Height, 'nearest_neighbor')
    *
    mirror_image (PolarTransImage, ImageMirror1, 'column')
    *下一步：OCR字符识别
   

最终效果如下图：

 下面附上另外3张图片，感兴趣的可以测试一下