1. A system for estimating a distance to an object, the system comprising: an imaging system; a sensor array, wherein the sensor array is disposed to receive one or more images of the object through the imaging system; a one or more masks disposed within the imaging system in front of the sensor array, the one or more masks being configured to encode one or more three-dimensional responses of the imaging system for calculating a point spread function that evolves as a function of a position of the object.