Circle Probe
The Circle Probe module provides a way to extract out a circle from a given image assuming that
the placement of the probe is in the approximate location of the circle. This module is used
in machine vision quality assurance techniques in order to determine if a particular part
meets specific quality assurance levels. For example, if your part requires that an
inner cut hole be of about 12 pixels in radius the Circle Probe module can be used to
extract out that diameter from the current image into a variable array. This variable array
then contains the center and radius of the circle which can then be examined by other
modules or exported to external applications.
Interface
Instructions
1. Current Image - move the probe graphic to the location which you want to probe
for circles. You drag the red square to move the entire probe, the cyan
and purple squares to expand or shrink the minimum and maximum radius, or
the green and blue squares to specify the angular range of the probe.
Likewise, you can move each endpoint individually by changing the coordinates using the
text boxes below in the Parameters area.
2. Options Identify - select how many circles you want to detect. Note that if you
select many circles to be identified you are not guaranteed to get that many
circles depending on the thresholding information below. The "Identify" number
specifies a maximal number of circles to detect.
3. Smooth Edge - to reduce noisy edges select the amount of smoothing that
should be applied to the edge prior to edge detection.
4. Circle Isolation - to avoid multiple circles from being detected together select how
many pixels each circle's center should be isolated from the next detected circle center.
5. Edge Threshold - to eliminate very weak edges from being detected as part of a circle
select an appropriate
edge threshold (0-255) that will remove edges whose edge intensity is below
the threshold. Note that smoothing the edge will also reduce the edge
intensity and thus the Edge Threshold will need to be adjusted after the
smoothness is specified.
6. Relative Threshold - to only select those edges that are significant
you can specify the relative threshold (0-100) that will remove
successive edges that are the relative threshold percent less than the
previous edge. For example, consider the highest 3 edge values as 130,
120 and 40. If the relative threshold is 50% then the last edge 40 would
be eliminated since 40 is less than 50% of 120. As 120 is 92% of 130
it is not eliminated (unless the threshold where set at 95%).
7. Show Circles - to visually see which edges are detected (in the main RoboRealm interface)
select the
appropriate Color and Thickness of the circle that will indicate where
in the image the edges have been detected.
Example
| Detected circle using above probe |
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Variables
PROBED_CIRCLES - an array consisting of the X, Y, and Radius
of each detected circle.
PROBED_CIRCLES_COUNT - the number of detected circles.
PROBED_CIRCLES_POINTS - an array consisting of the X, Y coordinates of
each detected edge point that was used to calculate the circles.
See Also
Origin Probe
Edge Probe
Line Probe
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