This is very similar to the way a clinometer is used. It is essentially a device that includes a laser-rangefinder, clinometer, and a compass. It requires the use of a laser rangefinder and clinometer. The compass is also available with a built-in clinometer as the Omnislope LED. This, with its sight mount that again included a sight clinometer, replaced the No 3. Horizon altitudes can be measured with a theodolite or a clinometer. The angle to the top is measured with the clinometer. In forestry, tree height measurement can be done with a clinometer using standardized methods. The instruments needed include a laser rangefinder or a tape measure and a clinometer. He began using an optical rangefinder and Suunto clinometer circa 1993-94 using the sine method. The angle to the top of the tree is measured with the clinometer. Geologists, foresters, surveyors, and archaeologists use this handheld compass and clinometer.