A computer-implemented technique can process overhead images of users in a line at a venue to obtain a user wait time for the line. The processing can include (a) identifying a user of the group of users that is second in the line to obtain a target user, (b) detecting when the target user becomes first in the line to obtain a start time, (c) after the target user becomes first in the line, detecting when the target user leaves the line to obtain an end time, (d) determining a period from the start time to the end time, and (e) calculating the user wait time by calculating a product of (i) the determined period and (ii) a quantity of the group of users in the line after the target user leaves the line. The calculated user wait time can then be output.