OpenCV KeyPoint: information about angle and octave

Question

I want to know more about KeyPoints, so can anyone told me what are

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KeyPoint::angle

In OpenCV docs was mentioned that angle is computed orientation of the

Answer 1

This may help with regards to the octave:

http://en.wikipedia.org/wiki/Gaussian_pyramid

Basically, the image is blurred to varying degrees. The degree at which the feature is found is the 'octave' level of that feature.