Worldwide, all GPS measurements are now based on the WGS84 datum. The North American Datum of 1983 (NAD83) and the World Geodetic System of 1984 (WGS84) are examples of these new datums. Using the GRS80 spheroid, new datums were developed both regionally and worldwide. This spheroid and its associated datums define the earth's shape by measuring and triangulating from an outside perspective and use the mass center of the earth as an absolute origin. Instead of defining the earth from surface measurements linked horizontally and related vertically to mean sea level, this new mathematical approximation was derived from a point located out in space. In 1980, a new spheroid, the Geodetic Reference System (GRS80), was developed from satellite measurements. As GPS, a satellite-based location system, matured and became accessible to the public, the need to extend and better define the earth's spheroid and associated datums became more pressing. More than 30 years ago, satellites began acquiring remote imagery. The calculations were done manually, in sections, over many years, and errors vary from station to station. Many NAD27 control points were calculated from observations taken in the 1800s. The spheroid NAD27 uses Clarke 1866 that originates at a surface point at Meades Ranch, Kansas. The North American Datum of 1927 (NAD27) is a classic example of an early, local earth-surface-based datum. The resulting datums were typically limited in extent and were tied to an origin point on the earth's surface. For those outside the field of cartography, map projections were often an issue, but datums, those absolute global frames of reference, were not.Īs mapping expanded globally, cartographers established coordinate reference frameworks that helped standardize mapping activities across wide areas. Typically, local coordinate systems were developed and vertical and horizontal control were derived from a local frame of reference or datum. Field surveying was performed on a local basis using traditional mechanical, optical, and laser equipment. Until recently, a comprehensive knowledge of-or even much interest in-datums was limited to mathematicians, geodesists, and geographers specializing in cartography. As surveying technology improved and data acquisition increased worldwide, the mathematical formulas and the related parameters used to describe the shape of our irregular earth continually improved and were expressed in spheroids such as Everest 1830, Airy 1849, Clarke 1866, Clarke 1880, and Krasovsky 1940. A datum defines the position of the spheroid relative to the center of the earth. Geographic coordinate systems use a spheroid to calculate positions on the earth. Prior to satellite mapping technology, the best approximation of the shape of the earth was the mathematically calculated geoid, which evolved into slightly flattened spheroids or ellipsoids. These are all very real examples caused, in large part, by using data sets lacking a common datum. GPS coordinates acquired by hikers show their position half way up a very steep cliff instead of on the mapped trail below. Fire hydrant points collected with GPS appear located in parking lots or inside buildings instead of out by the curb. The same features in two street centerline themes or coverages may appear offset by many meters or feet. Internal applications, then our B2B based Bizapedia Pro API™ might be the answer for you.When was the last time you thought about what datum the data you were using was in? Perform analysis using data sets created in different datums or even display them together and you won't like the results. If you are looking for something more than a web based search utility and need to automate company and officer searches from within your WHAT'S INCLUDED IN THE ADVANCED SEARCH FORM? Utilize our advanced search form to filter the search results by Company Name, City, State, Postal Code, Filing Jurisdiction, Entity Type, Registered Agent,įile Number, Filing Status, and Business Category. While logged in and authenticated, you will not be asked to solve any complicated Recaptcha V2 challenges. In addition, all pages on Bizapedia will be served to you completely ad freeĪnd you will be granted access to view every profile in its entirety, even if the company chooses to hide the private information on their profile from the general public. Your entire office will be able to use your search subscription.
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