Projection And Coordinate System In Gis Pdf

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A geographic coordinate system GCS defines locations on the earth using a three-dimensional spherical surface [1] , it is a reference system that uses latitude and longitude to identify locations on a spheroid or sphere. A datum , prime meridian , and angular unit are parts of a GCS [2].

GIS data differs from other data types, primarily because it contains geographic coordinates describing the location of the data on the earth. Registration Policy.

Each polygon would represent an area such as a field, water body or building boundary. For example, your area of interest may be a school campus and all of the buildings, parking lots, sports fields and bike lanes that fall within that area. This information can typically be mapped. These help provide references and added background information to your GeoPortal search and results.

Introduction to Coordinate Systems and Projections

You are viewing an old version of this page. View the current version. Compare with Current View Page History. If you find these tutorials useful and would like to link to them from your own pages,please contact the Drew Spatial Data Center Director, Dr. Catherine Riihimaki via email. You are invited to leave comments or ask questions in any of the Comment areas of each tutorial page. In order for multiple map layers to work properly together, they must all use the same Coordinate System.

The magic of geographic information systems is that they bring together and associate representations from diverse sources and infer relationships based on spatial references. This ability depends on our data sources using well defined coordinate referencing systems. This is not to say that the coordinate systems need to be the same for each data source, only that the relationship between the coordinate references with some shared conception of the surface of the earth needs to be well described. Indeed, there are thousands of perfectly legitimate coordinate systems in active use. The notion of spatial referenicing systems is one of the most fundamental and interesting ideas that all users of GIS should understand. This document provides an overview of the basic ideas.

Geographic Information Systems and Geomatics

Map projections try to portray the surface of the earth or a portion of the earth on a flat piece of paper or computer screen. A coordinate reference system CRS then defines, with the help of coordinates, how the two-dimensional, projected map in your GIS is related to real places on the earth. The decision as to which map projection and coordinate reference system to use, depends on the regional extent of the area you want to work in, on the analysis you want to do and often on the availability of data. There is, however, a problem with this approach. They are also only convenient to use at extremely small scales e. Most of the thematic map data commonly used in GIS applications are of considerably larger scale.

It also allows the user to define custom coordinate reference systems and supports on-the-fly OTF projection of vector and raster layers. All of these features allow the user to display layers with different CRSs and have them overlay properly. Normally, you do not need to manipulate the database directly. In fact, doing so may cause projection support to fail. Custom CRSs are stored in a user database. See section Custom Coordinate Reference System for information on managing your custom coordinate reference systems. In order to use OTF projection, either your data must contain information about its coordinate reference system or you will need to define a global, layer or project-wide CRS.

Enroll now! Learn more. On the previous page, you explored the basic concept of a coordinate reference system. You looked at two different types of Coordinate Reference Systems:. As you discussed in the previous lesson, each CRS is optimized to best represent the:. Some CRSs are optimized for shape, some are optimized for distance and some are optimized for area. Geographic coordinate systems which are often but not always in decimal degree units are often optimal when you need to locate places on the Earth.

Introduction to Coordinate Systems and Projections

It only takes a minute to sign up. Can somebody please explain what is the difference between the Coordinate system WGS 84 for example and a Projection Universal Transverse Mercator for example? Both examples are coordinate systems. Geographic coordinate systems are based on a spheroid and utilize angular units degrees.

Handbook of Satellite Applications pp Cite as. The role of spatial data for decision making has increased the need for geographic information systems. This chapter starts by briefly describing the theory of geographic information systems.

Map Projections and Coordinate Systems

The shape of the earth is roughly spherical wheres as maps are two dimensional. Map projection is a set of techniques designed to depict with reasonable accuracy the spherical earth in a two-dimensional i. Map projection types are created by an imaginary source of light projected inside the earth. Common Map Projections.

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A Brief History and Theory of Latitude and Longitude

Все происходящее напомнило ему нечеткую фотографию. Мысли его то и дело возвращались к Сьюзан: он надеялся, что она уже прослушала его голос на автоответчике. Чуть впереди, у остановки, притормозил городской автобус. Беккер поднял. Дверцы автобуса открылись, но из него никто не вышел. Дизельный двигатель взревел, набирая обороты, и в тот момент, когда автобус уже готов был тронуться, из соседнего бара выскочили трое молодых людей.

2 Response
  1. Brenda M.

    ArcGIS and ArcGIS Pro Projected Coordinate System Tables. Note: Values may be rounded for display. Area of use values are in decimal degrees.

  2. Esopo D.

    Commonly Used Map Projections Working with Coordinate Systems in GIS Task 1: Project a Feature Class from a Geographic to a Projected.

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