Answered by:
About these two variables in SkeletonFrame: SkeletonFrame.FloorClipPlane and .NormalToGravity
Question

Answers

Are you sure that the Y value of FloorClipPlane is positive? I'd expect it to be negative, pointing downwards. The X,Y,Z values should be the unit vector pointing in the direction of the floor from the kinect camera (at position {0,0,0}), and the W value should be the distance, in meters, from the Kinect camera to the floor, along the unit vector specified as {X,Y,Z}.
So, X,Y,Z value should already be normalized to unit length. Consider W value separate from normalized floor direction vector.
Eddy
I'm here to help Marked as answer by Eddy EscardoRaffo [MSFT] Monday, October 10, 2011 7:39 PM
All replies

NormalToGravity is not actually supported in the Beta 1 Refresh release. FloorClipPlane should be initialized, however, as long as Kinect device can see enough of the floor to give a value for this with high confidence. Can you send a sample image of what your depth frame looks like so we can get a better idea of your setup?
Thanks!
Eddy
I'm here to help 

Hmmm, I would definitely expect FloorClipPlane to be initialized in your application, with W value giving you distance to floor (in meters), whenever one or more SkeletonData object has its TrackingState field initialized to SkeletonTrackingState.Tracked. Can you share some of your code where you try to use SkeletonFrame.FloorClipPlane?
About left side of depth image being all zeros, it is a known issue that you should work around if it's causing you problems.
Eddy
I'm here to help 
Hi Eddy,
I'm currently not using the values in FloorClipPlane yet, would you please explain the meanning of these values, plz?
For example, what I get for the frame above is : W X Y Z = 1.743904 0.006349928 0.9304801 0.3662871;
Thank you!
Chenyang
Chenyang 

Are you sure that the Y value of FloorClipPlane is positive? I'd expect it to be negative, pointing downwards. The X,Y,Z values should be the unit vector pointing in the direction of the floor from the kinect camera (at position {0,0,0}), and the W value should be the distance, in meters, from the Kinect camera to the floor, along the unit vector specified as {X,Y,Z}.
So, X,Y,Z value should already be normalized to unit length. Consider W value separate from normalized floor direction vector.
Eddy
I'm here to help Marked as answer by Eddy EscardoRaffo [MSFT] Monday, October 10, 2011 7:39 PM

