Filtering line segments by length and magnitude does not seem to do much?

OpenMV Boards
1

I have a H7, and added the following code to the bottom of the “find_line_segments” sample:

if l.magnitude() > 100: img.draw_line(l.line(), color = (0, 0, 255))
if l.length() <= 35: img.draw_line(l.line(), color = (0, 255, 0))

It runs, but regardless of a change in the magnitude, or length values, the green and blue lines drawn to screen barely change, and I barely get one or two. I would have thought changing magnitude to >1 would produce many blue lines?

Thanks in advance

2

You should print() the magnitude and length values.

3

Thank you for the input. I have the H7 camera pointed at an analogue clock youtube video. I am trying to isolate the three hands with this code:

for l in img.find_line_segments(merge_distance = 5, max_theta_diff = 15) :
if l.length() > 15 and l.magnitude() > 7: img.draw_line(l.line(), color = (0, 0, 255))
print(l)

I am still not able to isolate the hands. I was thinking my next attempt would filter by endpoints, given that all the hands have the same origin? Any suggestions are much appreciated. I should probably try different camera settings?

regards,

Bob Callaghan

4

Yes, basically… you’re going to have to do things like this. This isn’t really that complex. If you’re good with lists and math in python the solution will emerge.

5

I hate to ask, but where on my frame buffer is x0, y0? or point to a reference would be good. The documentation I looked at didn’t specify this?

6

Top left. Standard for images.