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  2. Levelling - Wikipedia

    en.wikipedia.org/wiki/Levelling

    There may be obstructions or large changes of elevation between the endpoints. In these situations, extra setups are needed. Turning is a term used when referring to moving the level to take an elevation shot from a different location. To "turn" the level, one must first take a reading and record the elevation of the point the rod is located on.

  3. Spirit level - Wikipedia

    en.wikipedia.org/wiki/Spirit_level

    A difference implies that the level is inaccurate. ... Precise levelling is supposed to give the difference in elevation between two points one kilometer (0.62 miles ...

  4. Benchmark (surveying) - Wikipedia

    en.wikipedia.org/wiki/Benchmark_(surveying)

    The terms "height" and "elevation" are often used interchangeably, but in many jurisdictions, they have specific meanings; "height" commonly refers to a local or relative difference in the vertical (such as the height of a building), whereas "elevation" refers to the difference from a nominated reference surface (such as sea-level, or a ...

  5. Glossary of levelling terms - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_levelling_terms

    The commonly used datum is mean sea level. [3] Dumpy level – optical instrument used to establish or check points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and to transfer, measure and set heights. Also called a builder's level or leveling instrument.

  6. Surveying - Wikipedia

    en.wikipedia.org/wiki/Surveying

    Differences in height between the measurements are added and subtracted in a series to get the net difference in elevation between the two endpoints. With the Global Positioning System (GPS), elevation can be measured with satellite receivers. Usually, GPS is somewhat less accurate than traditional precise leveling, but may be similar over long ...

  7. Level (optical instrument) - Wikipedia

    en.wikipedia.org/wiki/Level_(optical_instrument)

    It is also known as a surveyor's level, builder's level, dumpy level or the historic "Y" level. It operates on the principle of establishing a visual level relationship between two or more points, for which an inbuilt optical telescope and a highly accurate bubble level are used to achieve the necessary accuracy. Traditionally the instrument ...

  8. Reduced level - Wikipedia

    en.wikipedia.org/wiki/Reduced_level

    It is a vertical distance between survey point and adopted datum surface. [1] Thus, it is considered as the base level which is used as reference to reckon heights or depths of other places or structures in that area, region or country. [2] The word "Reduced" here means "equating" and the word "level" means "elevation".

  9. Topographic prominence - Wikipedia

    en.wikipedia.org/wiki/Topographic_prominence

    A way to visualize prominence is to imagine raising sea level so the parent peak and subject peak are two separate islands. Then lower it until a tiny land bridge forms between the two islands. This land bridge is the key col of the subject peak, and the peak's prominence is its elevation from that key col.