The MCvSURFPoint type exposes the following members.
Orientation of the feature: 0..360 degrees
Value of the hessian (can be used to approximately estimate the feature strengths; see also params.hessianThreshold.
-1, 0 or +1. sign of the laplacian at the point. can be used to speedup feature comparison (normally features with laplacians of different signs can not match)
Position of the feature within the image
Size of the feature