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The OpenMV Cam can now infinite lines and line segments from those infinite lines. find_lines has been updated to allow all this to work.
56 lines
2.5 KiB
Python
56 lines
2.5 KiB
Python
# Find Line Segments Example
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#
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# This example shows off how to find line segments in the image. For each line object
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# found in the image a line object is returned which includes the line's rotation.
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# Note: Line detection is done by using the Hough Transform:
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# http://en.wikipedia.org/wiki/Hough_transform
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# Please read about it above for more information on what `theta` and `rho` are.
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enable_lens_corr = True # turn on for straighter lines...
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import sensor, image, time
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sensor.reset()
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sensor.set_pixformat(sensor.RGB565) # grayscale is faster
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sensor.set_framesize(sensor.QQVGA)
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sensor.skip_frames(30)
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clock = time.clock()
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# All lines also have `x1()`, `y1()`, `x2()`, and `y2()` methods to get their end-points
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# and a `line()` method to get all the above as one 4 value tuple for `draw_line()`.
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while(True):
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clock.tick()
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img = sensor.snapshot()
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if enable_lens_corr: img.lens_corr(1.8) # for 2.8mm lens...
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# `threshold` controls how many lines in the image are found. Only lines with
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# edge difference magnitude sums greater than `threshold` are detected...
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# More about `threshold` - each pixel in the image contributes a magnitude value
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# to a line. The sum of all contributions is the magintude for that line. Then
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# when lines are merged their magnitudes are added togheter. Note that `threshold`
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# filters out lines with low magnitudes before merging. To see the magnitude of
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# un-merged lines set `theta_margin` and `rho_margin` to 0...
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# `theta_margin` and `rho_margin` control merging similar lines. If two lines
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# theta and rho value differences are less than the margins then they are merged.
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# Setting both the above to zero will greatly increase segment detection at the
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# cost of a lot of FPS. This is because when less lines are merged more pixels
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# are tested... which takes longer but covers more possibilities...
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# `segment_threshold` controls line segment extraction. It's a threshold on the
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# magnitude response per pixel under an infinite line. Pixels with a magnitude
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# above threshold are added to the line segment.
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# `find_line_segments` merges detected lines that are no more than 5 pixels apart
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# and no more than 15 degrees different to create nice continous line segments.
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for l in img.find_line_segments(threshold = 1000, theta_margin = 15, rho_margin = 15, segment_threshold = 100):
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img.draw_line(l.line(), color = (255, 0, 0))
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# print(l)
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print("FPS %f" % clock.fps())
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