Introduction
When you need to accurately enter coordinates in a GIS, the first step is to uniquely define all coordinates on Earth. This means you need a reference frame for your latitude and longitude coordinates. Because the Earth is curved and in GIS we deal with flat map projections we need to accommodate both the curved and flat views of the world. Surveyors have accurately defined locations on Earth. We begin modelling the Earth with an ellipsoid. To be clear, this is different than a geoid which is a measure of mean sea level. Over time, the ellipsoid has been estimated to the best of our ability through a massive collection of surface measurements.
When you combine
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It was in the year 1980 when the need for world geodetic system was recognised by the so called the geodetic community, also within the US Department of Defense.
The earliest used geodetic system no longer provide sufficient data, information, geographic coverage, or product accuracy for all the-current and anticipated applications. The means for producing a new WGS84 were available in the form of improved data, increased data coverage, new data types and improved techniques.
The new world geodetic system called WGS84 is an acronym for World Geodetic System 1984. It is a standard for various activities related to mapping for an example: Navigation, Cartography and Geodesy. The World Geodetic System 1984 (WGS84) is the datum used by the Global Positioning System (GPS).
Within the World Geodetic System (WGS), there are several datums that have been in use throughout the years. These are WGS 60, 70, 72, and 84. The WGS84 is currently one in use for this system. In addition, it is one of the most widely used datums around the
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WGS84 coordinates system are geographically positioned with respect to center of the earth. Such a system is called ECEF (Earth-centered, Earth fixed). The WGS84 coordinate is a three-dimensional, right-handed, Cartesian coordinate point at the center of mass of an ellipsoid, which approximate the total mass of the earth. Figure 2.1 and 2.2 below shows the geographically positioned coordinate with respect to the center (ECEF). And figure 2.3 shows what it is meant by right-handed Cartesian
Until the 1950s, Atlases were mostly comprised of maps that simply show space and place. However in 1953, the World Geo-Graphic Atlas, published by Walter Paepcke’s Container Corporation of America (CCA) with Herbert Bayer, changed people’s notion of what maps look like and what information they contain. Bayer believed, that maps were “a record of time and perhaps even a tool of prognostication.” By the use of Isotypes (International System of Typographic Picture Education), Bayer created an atlas that is universal, therefore allowed viewers to understand complex data more clearly and easily.
The invention of the GPS started with Dr. Ivan Getting leaving his position at Raytheon Company, and armed with the knowledge of what was at the time the most advanced navigational technology in the world, they began developing the Global Positioning System. He, Roger L. Easton, and Bradford Parkison began in the 60’s with a constellation of 24 satellites (placed in six orbital planes) orbiting the earth at a very high altitude (about
Dava Sobel’s novel, Longitude: The True Story Of A Lone Genius Who Solved The Greatest Scientific Problem Of His Time is a history of the scientific battle to obtain a method of finding the exact longitude of a specific location. Knowing the longitude of a location may seem unimportant, but in fact it is vital. To fully understand the work that went into this effort, first, one must understand the basic principles for determining location on Earth.
Abstract: This paper focuses on modeling the errors which normally degrade the accuracy of Global Poisoning System (GPS). The performance of the GPS is mainly affected by ionospheric errors. SiRF Star III single frequency receiver is used for collecting and projecting datum in World Geodetic System 1984 (WGS-84) co-ordinate form. To project the ellipsoidal model onto a map model, datum conversion from WGS-84 to Universal Transverse Mercator (UTM) form is needed. The conversion introduces errors in the datum. The variation in the errors can be observed from day to night, area to area and also due to the seasonal changes. The datum is collected from Ameerpet region of Hyderabad, which is a heavily populated area with heavy traffic and tall buildings. The variation in the datum has been observed from afternoon to evening.
The document is in the form of a map which would categorize it as spatial. While it is not a map that could be used to find a specific location, it does follow some of the characteristics of what is expected of a map. It is based on
You need to understand and be able to construct geometric figures by using a compass and a straightedge. Both the compass and the straightedge were used before when the computers were invented. The first person to use a compass and straightedge was Euclid, “the father of geometry”. Drafting with both of these tools were the foundation of all geometric constructions.
The following is a brief illustration of the principles of GPS. For more information see previous chapter. The Global positioning System (GPS) is a satellite-base navigation system that provides a user with proper equipment access to positioning information. The most commonly used approaches for GPS positioning are the Iterative Least Square (ILS) and the Kalman Filter (EKF) methods. Both of them are based on psuedorange equation:
GPS is a navigational aid that is satellite based. It is made up of a network of 24 satellites in orbit around the world. The first satellite was launched in 1978 and the last was put into orbit in 1994. Every 10 years another satellite is put into orbit because each satellite is made to last that amount of time. The system began as a military application but in the 1980’s the government decided to make it available to everyone, anywhere, anytime. The system finds your position by measuring the time it takes to receive the signal back to the satellite. It then does that with other satellites to triangulate your position in relation to the earth. To calculate a position in 2D the system has to be locked on to at least three satellites, but for a 3D representation you need to be locked on to at least 4 satellites. Once the position is found the GPS can calculate much more info like speed, bearing, track, distance, etc… The GPS system is very accurate; Garmin (a leader in GPS technology) states that their newest receiver is accurate up to an average of 15 meters.
Within Offshore Surveying, GNSS has always been prominent throughout the years. From its initial land based methods of using antenna to the ‘Free-to-Air’ systems used today. Throughout this essay the views in which will be assed are the historical and present day use of GNSS in Offshore Surveying; How GNSS provides the accuracy needed and the limitations it must overcome; What the possible alternatives there could be to GNSS and its advantages and disadvantages faced when using GNSS; The future for GNSS and its development and finally looking at practical real life case studies of GNSS and how it is effectively used within an offshore surveying company. The essay will look at these points individually and separate itself accordingly into five many sections reflecting the points rose previously to give an accurate account of the role GNSS has had, and will play, in Offshore Surveying.
The Global Positioning System consists of three sections, 1.satellites which are orbiting the planet, 2.there are numerous control/monitoring centers here on the ground, and 3. gps receivers which are used by their owners. The satellites send down signals from orbit, which are received by GPS receivers on the ground in the air or on the water, the GPS receiver then converts this information into a location longitude, latitude and altitude along with time.
It remained a problem in geography until the invention of chronometers at the end of the eighteenth century. It must be added that his original topographic list cannot be reconstructed. The long tables with numbers were transmitted to posterity through copies containing many scribal errors, and people have always been adding to or improving the topographic data. This can be viewed as a testimony to the persistent popularity of this influential work.” http://www.newworldencyclopedia.org/entry/Ptolemy Ptolemy in Geometry “Ptolemy was a first-rate geometer and mathematician who devised important new geometrical proofs
The Global Positioning System, more commonly called the GPS is a satellite based system that provides navigation for almost everything from cell phones to automobiles. This wonderful technology is very vital in today’s economy because of its prominence in banking, financial markets, power grids, farming, construction and so much more. It also protects human life by preventing accidents, helping in search and rescue missions and is critical to nearly every facet of military operations. There are three segments that make up the global positioning system: the space segment, the control segment and the user segment. The segment we are familiar with is the user segment. The user segment is what receives GPS signals, determines the distance between a satellite and a receiver and solves the navigation equations, all in order to obtain the coordinates of a specific place. The space segment consists of 31 satellites but there is an availability of at least 24 satellites that are approximately 6 000-12 000 miles above the earth.
Intro During the past centuries numerous scientists have devoted their lives to charting the world’s oceans. Longitude and latitude can provide accurate locations and distances, which proved crucial in numerous scenarios. The objective of this lab was to learn how to read and create charts.
Created in 1569, the defining feature of the Mercator map is it's introduction of a projection system that is still in use today. The Mercator projection was created by Gerardus Mercator for use in nautical navigation, and is characterised by its ability to represent straight courses through rhumb lines.19 This map became the standard for most nautical use, and subsequently the most popular type of world map, even until today. The original version of his map notably distorts the sizes of continents, with North America vastly larger than it should be and Europe being displayed as equal in size to Africa. Although more accurate renderings have been made, this distortion is still present in maps today and is an example of Eurocentric bias, whether conscious or
Geographers plan new communities, decide where new highways should be placed, and establish evacuation plans. Computerized mapping and data analysis is known as Geographic Information Systems (GIS), a new frontier in geography. Spatial data is gathered on a variety of subjects and input onto a computer. GIS users can create an infinite number of maps by requesting portions of the data to plot.