1. A range camera operable to determine distances to and reflectance for features of a scene that the range camera images, the range camera comprising: a light source operable to transmit light to illuminate a scene that the range camera images; a photosensor having a plurality of light sensitive pixels; optics having an optical axis and optical center configured to receive light reflected from the transmitted light by features in the scene and image the reflected light on the plurality of pixels, each of which pixel of the plurality of pixels registers reflected light from a feature of the scene that the optics images on the pixel to provide a registered scene irradiance (RSI) for the feature; a calibration image comprising a registered calibration irradiance (RCI) for each of the plurality of light sensitive pixels that provides a measure of irradiance that the pixel registers responsive to light reflected from light transmitted by the light source by a region of a calibration surface having known shape, reflectance, and location that the range camera images on the pixel; and a controller operable to determine a reflectance for a feature of the scene imaged on a first pixel of the plurality of pixels responsive to the RSI for the feature and an RCI for a region of the calibration surface imaged on a second pixel of the plurality of pixels corresponding to the feature imaged on the first pixel.