1. An apparatus comprising: a communication interface configured to receive an image from an image source; a positioning module configured to control one or more navigation sensors to capture a first plurality of navigational measurements, and determine a position of the apparatus relative to a reference point based at least in part on the first plurality of navigational measurements; an image capture module configured to control one or more optical imaging sensors to capture a first plurality of surface images of a first medium adjacent to the apparatus; and a print module configured to cause a printing substance to be deposited on the first medium based at least in part on (i) the image received by the communication interface, (ii) the determined position of the apparatus, and (iii) a determination that a drop volume of the printing substance, previously deposited at the determined position, is less than a total drop volume for the determined position.