Projecting a structured light pattern onto a surface and detecting and responding to interactions with the same

An apparatus comprising:

• a first projector operable to project a structured light pattern onto a projection surface, the structured light pattern being composed of light of a particular wavelength;
• an image sensor operable to acquire images based on light of the particular wavelength reflected from a vicinity of the projection surface;
• and
• one or more processors operable collectively to:
• (a) identify regions of an acquired image that correspond to a feature that is within a specified distance of the projection surface by identifying regions of the acquired image for which intensity data differs relative to other regions of the acquired image and which fit a specified homographic relationship with respect to corresponding regions of a reference image, and generate a binary image in which regions of the acquired image that are determined to correspond to the feature within the specified distance of the projection surface are assigned a first value, and regions of the acquired image that are determined not to correspond to the feature within the specified distance of the projection surface are assigned a second different value;
• (b) use the binary image to determine that the feature is a particular type of object;
• (c) repeat (a) and (b) one or more times for at least one other acquired image;
• (d) perform frame-to-frame tracking to determine a path of movement of the object;
• and
• (e) determine that the object's path of movement represents a specified type of gesture.