1. A method of estimating height and tilt angle of a camera system having a 2-dimensional array of image sensors and a plurality of IR illuminators in fixed locations relative to the array of image sensors, comprising: at a computing device having one or more processors, and memory storing one or more programs configured for execution by the one or more processors: identifying a plurality of distinct subsets of the IR illuminators; partitioning the image sensors into a plurality of pixels; for each of the plurality of distinct subsets of the IR illuminators, receiving a captured IR image of a scene taken by the array of image sensors while the respective subset of the IR illuminators are emitting IR light and the IR illuminators not in the respective subset are not emitting IR light; using at least one of the captured IR images to identify a floor region corresponding to a floor in the scene; forming a vector including pixels from the captured IR images in the identified floor region; and estimating a camera height and camera tilt angle relative to the floor by comparing the vector to a dictionary, wherein the dictionary includes entries that correspond to the camera system having a plurality of heights and tilt angles.