How to get the saved feature point

[ptzu]

Hi,
I try to get the feature point with the cv::keypoint format:
_pt x & y coordinates of the keypoint
_size keypoint diameter
_angle keypoint orientation
_response keypoint detector response on the keypoint (that is, strength of the keypoint)
_octave pyramid octave in which the keypoint has been detected
_class_id object id

I'm not clear with the bundler_sfm output file.
How should I get them?