View Full Version : What does this I/O Message means?
magical hands
01-02-2006, 15:55
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all of a sudden I lost patience ang got mad. So i thought that the default colour values are not working therefore i chose to calibrate it and use my own colour values.
Red: min 56, max 106
Green: min 215, max 255
Blue: min 201, max 251
Than i brought the lights close in front of cam and i see the below message:
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Pan angle (Degrees) = -20
Titl angle (Degrees) = 5
Pan error (Pixels) = 43
Tilt error (Pixels) = 82
Blob Size = 1
Confidence = 14
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What does this message means and what should my next step be?
What does this message means and what should my next step be?
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The camera is looking for the green target but hasn't found it yet
The Block of text reports the following information:
1. Pan Angle (degrees):
• The position of the Pan Servo relative to center (127) represented in
degrees.
2. Tilt Angle (degrees):
• The position of the Tilt Servo relative to center (127) represented in
degrees.
3. Pan Error (Pixels):
• How far off (in Pixels) from the vertical center of the color blob the sensor
is aimed.
4. Tilt Error (Pixels):
• How far off (in Pixels) from the horizontal center of the color blob the
sensor is aimed.
5. Blob Size (Pixels):
• The size of the color blob (in Pixels) reported from the Sensor.
6. Confidence:
• The (# of pixels being tracked / area of the bounded rectangle)*256 and
capped at 255.
...Find all this and more at http://kevin.org/frc/CMUcam2_workbook.pdf
The first thing that would concern me is how high your error numbers are and how small your blob size is. If you haven't modified the code, it should move to where the target is once it aquires it and the error size should go down to something within the defined acceptable error. I don't remember what the default values are off the top of my head, something on the order of 5 pixels or so. If it doesn't home in on the center of the target, check the code in tracking.c.
How far away from the target are you?
Also, I don't think that you should need to change the color values from the default ones that Kevin gave you. They seem to work all right in most cases and most light. We've tried it in varying conditions, from all the lights off, to sunlight, and there was very little variation in tracking conditions (bright natural light seemed the worst).
Keith Watson
10-02-2006, 21:33
6. Confidence:
• The (# of pixels being tracked / area of the bounded rectangle)*256 and
capped at 255.I searched that document and the forums. Which "bounded rectangle"? The target blob? The camera sensor?
Andrew Blair
10-02-2006, 21:37
I searched that document and the forums. Which "bounded rectangle"? The target blob? The camera sensor?
This is the smallest rectangle that will fit around the color blob. By dividing the area by the # od pixels contained, you can find the pixel density, or "confidence" of the track.
Keith Watson
10-02-2006, 22:36
Thanks.
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