Patent ID: 7813887

Claim:
A location measurement system, comprising: a GPS receiver configured for attachment to a person and for determining earth location of the person; at least one of a display and an audio feedback that is attachable to the person; memory storing map data wherein the map data includes 3-D topographical information; and a processor configured to process the earth location and the map data to instruct display of a person's current location with a map on the display, detect contact with ground based upon movement of the person over the ground, determine vertical drop of the person based upon the movement of the person over the ground during at least one time interval in which lack of contact with the ground is detected followed by subsequent detection of contact with the ground; and compare the vertical drop of the person to a vertical drop determined for another person; wherein the comparison of the vertical drop of the person to the vertical drop determined for another person is configured for output to the at least one of the display and the audio feedback.