yeah, they're digitised renderings of the surfaces facing the virtual camera. the surfaces represent the computer's calculations of the relative locations of virtual 3D objects in a virtual 3D space, and the appearance is altered by calculations involving virtual lights, texture maps, reflection maps, shadow maps, etc. as it stands now, art snobs often say they're not art, since they're entirely computer-generated, but 100 years from now they'll probably be recognised as art, as they currently require at least some minimal amount of human intervention to create digital images. that won't be the case in the future, when similar renderings will be an wholly automatic machine process, with absolutely no human involvement required.