  Scanning photocurrent maps of gapless materials, such as graphene, often
exhibit complex patterns of hot spots positioned far from current-collecting
contacts. We develop a general framework that helps to explain the unusual
features of the observed patterns, such as the directional effect and the
global character of photoresponse. We show that such a response is captured by
a simple Shockley-Ramo-type approach. We examine specific examples and show
that the photoresponse patterns can serve as a powerful tool to extract
information about symmetry breaking, inhomogeneity, chirality, and other local
characteristics of the system.
