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Circle center detection and measurement
Anonymous
10 years
Hi,

I have tried to use roborealm to detect and measure accurately circle center. However, when I use the program to detect and measure the circle in the picture below, it supplies me a circle with a clear offset. What can I do to prevent this?
program.robo
Anonymous 10 years
including the picture in the tread
Anonymous 10 years
Michel,

Your robofile was blank ... but we got the image and noticed a problem when using a large image and the circle detector. It was geared towards 320x240. We made a change to better adapt to larger images and have uploaded a new version 1.7.22.4 that should give you a better estimate. Included are the resulting image we get and the robofile used to generate that image using the latest version.


program.robo
Anonymous 10 years
Thanks for the program. What is the accuracy of the center measurement?
Anonymous 10 years
That's a difficult question to answer as it will depend on what you need. The algorithm will return a X,Y pixel as the center and an integer as the radius. Thus the precision is limited to integer numbers. The circle will wiggle during video processing based on this integer limitation so the accuracy will also be +-1 a pixel. This assumes that the lighting, camera, temperature, etc all stay the same as these many factors can cause the image to change slightly. Even a slight change may cause the edge processing to favor one pixel over another and thus change the circle dimensions slightly.

What kind of accuracy are you looking for?

STeven.
Anonymous 10 years
The cricle recognition is used for alignment. I agree that the quality of the image plays a large role in the acheivable accuracy. So if the algoritm stays within +/- 2 pixel I still consider it quite good.

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