Methods and systems for automatically determining the height of an object observed by a camera are described. The multi-media identity can be a digital identifier defining multi-media authentication data and security privileges for the entity. The optical link includes a number of optical channels. The activity monitor records and allows for the analysis of the recorded data to determine is there is a likelihood of substance abuse. A vehicle damper may include one or more variable orifice area low velocity valves in combination with other valves of conventional construction.