What Is Survey North?
север изыскания is the reference point used on surveys to indicate the true north of the land. This is important because if you know the true north of the area, it will be much easier to navigate from one location to another.
Surveys of any complexity can be based on either the magnetic or true north reference system, and a number of other methods may be used. However, when the two systems are not in agreement, a geodetic survey can be performed that uses a more precise map of the earth to determine the exact position of permanent points on the ground.
Whether a map indicates true north or magnetic nadir depends on the original surveyor and how they determined true north. Typically, a compass is used to make this determination. This is a more accurate reading than the one a consumer would use, but it is still inaccurate by as little as a few degrees.
If a map shows true north, it can also be determined by observing the declination, which is the change in direction of the compass needle from its normal point. This declination error can be measured in degrees, and the value can vary from several to ten degrees.
In the public land surveying system, a parcel is generally identified by its section, township, and range. This information is then recorded in the National Geodetic Survey Data Explorer.
A survey plat or survey map is a sheet of paper that outlines the boundaries of the land. These documents show the property's actual location, and often have symbols that indicate where pins from prior surveys were placed (existing pin), monuments, easements and other information.
It is possible to read a survey plat in reverse, which can be useful for finding corners. For example, a line showing that it travels N 15deg 30' 45' E can be described as traveling S 15deg 30' 45' W if you are facing West while following the survey.
Benchmarks are a key component of the NGS database, with more than 240,000 stations gathered over the last two centuries across the country. These benchmarks are marked with their latitude and longitude, along with a six-character alphanumeric code, indicating where they are located.
The National Geodetic Survey Data Explorer shows a listing of each benchmark that is maintained by NGS, with its latitude and longitude. These benchmarks are found in both the US and Canada, and many have scaled positions from maps.
In addition, there are a large number of historical survey benchmarks that have been hunted by geocachers, and the resulting data is stored in a special database for the public to view. These historical markers provide a unique way to explore and learn more about the history of the area that you live in.
As an important part of their work, geodesists have honed mathematical models of the earth that form a primary spatial reference system. This spatial system allows them to accurately map and demarcate land, and complete other geomatics tasks. Using these models and other tools, they make measurements that are critical to the world we live in.