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angle estimation accuracy in C++ cv::phase

asked 2013-04-09 09:57:05 -0500

uvts_cvs gravatar image

In phase documentation is stated:

The angle estimation accuracy is about 0.3 degrees.

Can you explain how that number is computed?

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answered 2013-04-09 12:21:57 -0500

It means that when computing the phase between two vectors, there is basically the result + or - 0.3 degrees. It says about because probably a large number of data was processed using the function and then an average was taken between this and the actual result it should be.

These deviations are due to precision of elements that are stored and rounding errors inside the mentioned function.

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Is there any theoretic background? Or is it just a brute force comparison?

uvts_cvs gravatar imageuvts_cvs ( 2013-04-10 12:32:23 -0500 )edit

I am guessing that they use a float percision, which means that a degrees in radian (which is done internally) is rounded. Small differences however when rounding vector dimensions could lead to a change in degrees when using sine and cosine functionality to calculate the angle. This is basic math, that sine and cosine do have rounding errors if you want processing to be fast enough.

StevenPuttemans gravatar imageStevenPuttemans ( 2013-04-10 13:25:31 -0500 )edit
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Asked: 2013-04-09 09:57:05 -0500

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Last updated: Apr 09 '13