1. A system comprising: a depth camera system to project a signal onto an environment and capture an image of the environment and a reflected signal; one or more processors communicatively coupled to the depth camera system; and memory having computer-executable instructions stored thereupon which, when executed by the one or more processors, cause the one or more processors to perform operations comprising: obtaining, from the depth camera system, an image of the environment and photons of the reflected signal; identifying one or more ambiguous pixels of the image, the one or more ambiguous pixels comprising pixels having a photon count of the photons of the reflected signal that is less than a threshold number of photons required to determine depth; analyzing a model of the environment that represents depth and reflectivity values of pixels of previously obtained images of the environment to identify an expected depth and reflectivity values for the one or more ambiguous pixels; comparing the expected depth and reflectivity values of the one or more ambiguous pixels with calibrated values; and based at least in part on the comparing the expected depth and reflectivity values of the one or more ambiguous pixels with the calibrated values, classifying the one or more ambiguous pixels as either dark pixels or far pixels.