false means that detector computes orientation of each feature. true means that the orientation is not computed (which is much, much faster). For example, if you match images from a stereo pair, or do image stitching, the matched features likely have very similar angles, and you can speed up feature extraction by setting upright=true.

public bool Upright { get; set; }

Public Property Upright As Boolean
	Get
	Set

public:
property bool Upright {
	bool get ();
	void set (bool value);
}

member Upright : bool with get, set