Abstract: A system and method for estimating the range to a target is based on logging images and related information as a vehicle is moving. When the vehicle is at a first observation point and an event of interest occurs at a target location, the log can be accessed to provide an image and related information of the target from a time in the past. This logged information provides a prior observation point, or in other words a second observation point, to use for triangulation, eliminating the need and time required to move the vehicle and acquire a second observation point. Using the current information from the first observation point, and the logged information of a prior observation point, triangulation can be used to estimate the range from the current observation point to the target.