Halcon line detection

1. Halcon's most commonly used straight line detection operator, add_metrology_object_line_measure, uses the Halcon packaged model to detect not only straight lines, but also circles, ellipses, rectangles, etc. The rest of the linear detection operators are introduced below, which need to cooperate with
skeleton (SelectedRegions, Skeleton)
gen_contours_skeleton_xld (Skeleton, Contours, 5, 'filter')
fit_line_contour_xld (Contours, 'tukey', -1, 0, 5, 2, RowBegin, ColBegin, RowEnd, ColEnd, Nr, Nc, Dist) gen_region_line (RegionLines, RowBegin, ColBegin, RowEnd, ColEnd) and other operators fit straight
lines
.
2. The operator is as follows

1. bandpass_image

Function: Extract edges using a bandpass filter.

2. lines_color

Function: Detect color lines and their width.

3. lines_facet

Function: Use surface model to detect lines.

4. lines_gauss

Function: Detect lines and their width.
3. Case explanation
3.1 bandpass_image

dev_close_window ()
dev_open_window (0, 0, 512, 512, ‘black’, WindowHandle)
dev_set_draw (‘margin’)
read_image (Image, ‘C:/Users/Dell/Desktop/2022_11_28_15_44_14_0588_id_36429.bmp’)
median_rect (Image, ImageMedian, 9, 9)
bandpass_image (ImageMedian, ImageBandpass, ‘lines’)
threshold (ImageBandpass, Regions, 21, 255)
connection (Regions, ConnectedRegions)
select_shape (ConnectedRegions, SelectedRegions, ‘area’, ‘and’, 536.53, 1000)
skeleton (SelectedRegions, Skeleton)
gen_contours_skeleton_xld (Skeleton, Contours, 5, ‘filter’)
fit_line_contour_xld (Contours, ‘tukey’, -1, 0, 5, 2, RowBegin, ColBegin, RowEnd, ColEnd, Nr, Nc, Dist)
gen_region_line (RegionLines, RowBegin, ColBegin, RowEnd, ColEnd)
original image

bandpass_image result image

fitting straight line

3.2 lines_color

read_image (Image, 'cable' + J)
dev_display (Image)
disp_message (WindowHandle, 'Color image', 'window', 12, 12, 'black', 'true')
disp_continue_message (WindowHandle, 'black', 'true')
stop ()
lines_color (Image, Lines, 3.5, 0, 12, 'true', 'false')
select_contours_xld (Lines, LongLines, 'contour_length', 450, 100000, 0, 0)
原图

Result Figure

3.3 lines_facet
read_image (Bk45, 'bk45')
dev_set_colored (6)
lines_facet (Bk45, Lines, 5, 3, 5, 'light')
original image

result Figure

3.4 lines_gauss
dev_update_off ()
dev_close_window ()
dev_close_window ()
*

• Read an aerial image
  read_image (Image, ‘mreut4_3’)
  dev_open_window_fit_image (Image, 0, 0, -1, -1, WindowHandle1)
  set_display_font (WindowHandle1, 16, ‘mono’, ‘true’, ‘false’)
  dev_display (Image)
  disp_message (WindowHandle1, ‘Extract the roads from an aerial image’, ‘window’, 12, 12, ‘black’, ‘true’)
  disp_continue_message (WindowHandle1, ‘black’, ‘true’)
  stop ()
• Segment the image and reduce the domain
  threshold (Image, Region, 160, 255)
  reduce_domain (Image, Region, ImageReduced)
• Detect the lines that represent the road centers
  MaxLineWidth := 5
  Contrast := 70
  calculate_lines_gauss_parameters (MaxLineWidth, Contrast, Sigma, Low, High)
  lines_gauss (ImageReduced, RoadCenters, Sigma, Low, High, ‘light’, ‘true’, ‘bar-shaped’, ‘true’)

original image

result graph