Surveyors take measurements of land to determine boundaries for property and other purposes. The data they provide is used for construction and engineering projects. They research land records, survey records, and land titles to pinpoint the exact boundary lines of real estate and other properties. Surveyors determine the precise location of roads and the needed depths of building foundations using tools such as GPS or tripod infrared reflectors and knowledge of geometry, physics, and engineering to measure the land. They establish land and water boundaries for deeds, leases, and other legal documents, and testify in court regarding survey work when necessary.