No Kinect for External Environments: Why?

Here's why Skeletal Tracking Algorithms used by Kinect does work so well in the external environments:

Kinect sensor isn't suited for outside/external environments. It is based off skeletal tracking. Now here's how skeletal tracking works: 

For the depth image we:
1) Thresholding on the depth image to extract the foreground from the image.
2) Noise is removed using morphological operations of erosion and dilation.
3) Further small blob removal is done to get a clean foregound segmented image.
4) This helps us focus on only the subject in the image and calculate the Extended Distance Transform.

For the RGB image we:
1) Face and upper body detection.
2) Skin Segmentation.
3) Arm Fitting

For the face and upper body detection, we use hear features in the viola-jones face detection algorithm. The hear features used are edge detectors, line features and centre surround features.

Problems in the external environment are:
1) Skeletal tracking doesn't work for non-humans.
2) Gestures/Human/environment movements cannot be tracked as easily using skeletal tracking when the perspective view is different or rather say sideways etc. A problem of the extended distance transform used.
3) Its far more difficult to morphologically clean up an image in the wide variety of external environments we can think of.

Ref: http://home.iitk.ac.in/~akar/cs397/Skeletal%20Tracking%20Using%20Microsoft%20Kinect.pdf