What Is A Benchmark On A Topographic Map

A benchmark is a marker that was placed in the ground when the surveyors were out making the map. Benchmarks are an important feature you can find on topographic maps. A single point of reference called a benchmark is used as a basis for the vertical data collection.

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Benchmarks are an important feature you can find on topographic maps.

What is a benchmark on a topographic map. One more thing to keep in mind is that a benchmark that shows on a topo map may not be in the ngs database which is used here. A benchmark is a marker that was placed in the ground when the surveyors were out making the map. In order to create a contour map or a topographic map the data and information obtained by the surveyor must be not only horizontally accurate but also vertically accurate. A benchmark is a marker that was placed in the ground when the surveyors were out making the map.

A fundamental benchmark is a point with a precisely known relationship to the vertical datum of the area typically mean sea level. I ve also seen instances where a triangle does not have the bm next to it but there is a triangulation station set there. The benchmark on the map corresponds to a metal plate placed in the real world environment which is also called a benchmark. A surveyor could place a surveying instrument on a tripod above that benchmark hang a plumb bob from the instrument to hang.

Benchmarks are an important feature you can find on topographic maps. The position and height of each benchmark is shown on large scale maps. This is a point where cartographers have precisely calculated. In surveying a bench mark two words is a post or other permanent mark established at a known elevation that is used as the basis for measuring the elevation of other topographical points.

A benchmark is just a point on the map so that you can see where on the map you are. A benchmark is a point of reference by which something can be measured. If you go looking in this park in lansdale you should be able to find a concrete marker in the ground with a circular brass disk about 3 inches across stuck in it right where the map shows the little x. As mentioned before the letters bm mean benchmark which means that a disk was set at the location of the x vertical benchmark station or at the location of the triangle triangulation station.

If it isn t in the database then there is not much that can be done other than write the usgs or whichever agency placed the benchmark if you are so inclined.