14. An electronic device comprising: a memory; a depth sensor; one or more processors, communicatively coupled to the memory, wherein the memory stores instructions to cause the one or more processors to: acquire a depth image of a scene in a vicinity of the electronic device using the depth sensor, the depth image having a first plurality of pixels, each pixel having a value indicative of a distance; store the depth image in the memory; develop a scene geometry based upon the depth image; determine that a user is engaging the electronic device; identify a human hand in a region of space based on the first plurality of values; identify a three-dimensional region about the human hand, wherein the three-dimensional region includes at least some of the first plurality of pixels; partition the three-dimensional region about the human hand into a second plurality of sub-regions, each sub-region having a corresponding value and size, wherein the value of a particular sub-region comprises a number of human hand pixels within the particular sub-region, wherein the sizes of the sub-regions are configured so that the number of human hand pixels within each sub-region is approximately equal, and wherein the sizes of the sub-regions are non-uniform; generate a feature vector for the human hand based on the values of the second plurality of sub-regions; apply the feature vector to a classifier; determine that the human hand is making an identified gesture based on output from the classifier; and cause an action to be taken by the electronic device, based, at least in part, upon the identified gesture and the scene geometry.
14. An electronic device comprising: a memory; a depth sensor; one or more processors, communicatively coupled to the memory, wherein the memory stores instructions to cause the one or more processors to: acquire a depth image of a scene in a vicinity of the electronic device using the depth sensor, the depth image having a first plurality of pixels, each pixel having a value indicative of a distance; store the depth image in the memory; develop a scene geometry based upon the depth image; determine that a user is engaging the electronic device; identify a human hand in a region of space based on the first plurality of values; identify a three-dimensional region about the human hand, wherein the three-dimensional region includes at least some of the first plurality of pixels; partition the three-dimensional region about the human hand into a second plurality of sub-regions, each sub-region having a corresponding value and size, wherein the value of a particular sub-region comprises a number of human hand pixels within the particular sub-region, wherein the sizes of the sub-regions are configured so that the number of human hand pixels within each sub-region is approximately equal, and wherein the sizes of the sub-regions are non-uniform; generate a feature vector for the human hand based on the values of the second plurality of sub-regions; apply the feature vector to a classifier; determine that the human hand is making an identified gesture based on output from the classifier; and cause an action to be taken by the electronic device, based, at least in part, upon the identified gesture and the scene geometry. 16. The electronic device of claim 14 , wherein the instructions further cause the one or more processors to monitor and analyze body or limb activity of a second user.