1. Apparatus for verifying the presence of a particular human individual at a given location at a given time by assessing both a visible identifying feature of said human individual and a representation of a code supplied to said individual, said apparatus comprising, in combination: (a) a computer database in which are stored at least one image of said visible identifying feature and other identification data of at least one registered human individual (“RHI”); (b) a first processor coupled to the database for (1) accessing selected information from the database, (2) generating and storing a first representation of a code, and (3) producing a code signal specifying said first representation; (c) a display device, for displaying said first representation of said code in response to said code signal received from said first processor; and (d) at least one first camera arranged to view both (1) an identifying feature of a putative human individual (“PHI”) located in proximity to said display device, and (2) said display device displaying said first representation of said code, for generating a composite image containing both said identifying feature of said PHI and said first representation of said code, for transmission to said first processor; wherein said first processor is further operative to: (i) receive said composite image and generate both (a) a second representation of said code, and (b) a representation of said identifying feature of said PHI, each from the received composite image; (ii) compare information contained in said stored first representation of said code with information contained in said generated second representation of said code; (iii) compare information contained in said stored RHI identifying feature with information contained in said representation of said identifying feature of said PHI; and (iv) indicate a verification that said PHI is the same individual as said RBI and that said PHI is located at the location of said display device, if both said (a) code comparison and (b) said identifying feature comparison each indicate respective substantially similar information.