US 9,811,721 B2
Three-dimensional hand tracking using depth sequences
Feng Tang, Cupertino, CA (US); Ang Li, Cupertino, CA (US); and Xiaojin Shi, Cupertino, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on May 7, 2015, as Appl. No. 14/706,649.
Claims priority of provisional application 62/037,923, filed on Aug. 15, 2014.
Prior Publication US 2016/0048726 A1, Feb. 18, 2016
Int. Cl. G06K 9/00 (2006.01); H04N 13/02 (2006.01); G06K 9/46 (2006.01); G06F 3/01 (2006.01); G06F 3/03 (2006.01); G06F 3/042 (2006.01); G06T 7/246 (2017.01); G06T 7/254 (2017.01); H04N 13/00 (2006.01)
CPC G06K 9/00355 (2013.01) [G06F 3/017 (2013.01); G06F 3/0304 (2013.01); G06F 3/0425 (2013.01); G06K 9/4609 (2013.01); G06T 7/246 (2017.01); G06T 7/254 (2017.01); H04N 13/0207 (2013.01); H04N 13/0271 (2013.01); G06T 2200/04 (2013.01); G06T 2207/30196 (2013.01); H04N 2013/0085 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An apparatus, comprising:
a depth-sensing camera;
a memory having, stored therein, computer program code; and
one or more processing units operatively coupled to the memory and configured to execute instructions in the computer program code that cause the one or more processing units to:
receive a depth map of a scene containing one or more human hands from the depth-sensing camera, the depth map comprising a matrix of pixels, each pixel having a depth value;
extract, from the depth map, features based on the depth values of the pixels in a plurality of patches distributed in respective positions over the one or more human hands, wherein the depth values of the pixels are normalized, such that the features are background-invariant;
match the extracted features to previously-stored features;
estimate a position of at least one of the one or more human hands based, at least in part, on stored information associated with the matched features; and
track the position of the at least one of the one or more human hands,
wherein the instructions to track comprise instructions to track bi-directionally along a z-axis of the scene.