Each position has two values that reference it to that central location. Projected coordinate systems a map projection is the systematic transformation of locations on the earth latitudelongitude to planar coordinates the basis for this transformation is the geographic coordinate system which references a datum map projections are designed for specific purposes. Hence, these are also called as map projection systems. Universal transverse mercator utm coordinate system is a standard set of map projections with a central meridian for each sixdegree wide utm zone.
A projected coordinate reference system is always depends on the geographic coordinate system. The difference is that wgs 84 is a geographic coordinate system, and utm is a projected coordinate system. Geographic coordinate systems, datums, spheroids, prime meridians, and angular units of measure current as of arcgis version 9. The universal transverse mercator utm coordinate syatem is commonly used in gis because it has been included since the late 1950s on most usgs topographic maps. The first layer added to an empty data frame sets the coordinate system for the data frame, but you can change it if necessary. If the first layer does not have a coordinate system. What are 2 types of coordinate reference systems in gis. Project a shapefile by using a predefined coordinate system.
Projections and coordinate system linkedin slideshare. Coordinate systems, map projections, and geographic datum. If you know the epsg code, the identifier, or the name for a coordinate reference system, you can use the search feature to find it. Projected coordinate system makes use of 2dimensional or flat plane surface representing earth surface objects. The polar coordinate system is extended into three dimensions with two different coordinate systems, the cylindrical and spherical coordinate systems. Coordinate reference system selector this dialog helps you assign a coordinate reference system to a project or a layer, provided a set of projection databases. Spcs was established to support surveying, engineering, and mapping activities in the united states and its territories. Arcmap will automatically set the data frames projection to be the same as that of the data. Heres the recipe for a projected coordinate system. A datum is a mathematicallydefined reference surface used to represent the size and shape of the earth. Note that the use of a projection defines a cartesian coordinate system and hence cre ates grid north, a third version of the north ern direction. Nov 14, 2019 to select a map projection, determine which of the properties is the most important for the project, and select the coordinate system or map projection that best preserves that property.
Specify a coordinate systemproperties of maps arcgis pro. A projected coordinate system is defined on a flat, twodimensional surface. A projection is a formula used to convert longlat coordinates into a flat coordinate system that you can use on paper or a computer screen. Choose properties at the bottom of the pop up menu. Its great creating maps, analyzing data for land use studies and other reports, and preparing data for use in an application or database. Some numerical values have been rounded for display. If required, you can change the coordinate system you assigned. The interest of a particular projection for a given usage depends upon the mathematical properties of the. A projected coordinate system based on a map projection such as transverse mercator, albers equal area, or robinson, all of which along with numerous other map projection models provide various mechanisms to project maps of the earths spherical surface onto a. But the gis software does need to convert your data to the same coordinate system behind the scenes. History, policy, and future directions 1 executive summary the state plane coordinate system spcs is a system of conformal map projections created by the national geodetic survey ngs. Heres the coordinates in dms of a control point in redlands, california, on the north american datum of 1983 nad 1983 or nad83. Click geolocation tab location panel edit location dropdown from map. The extent values for an area of use are in decimal degrees based on wgs 1984.
Tntmips pro is a professional system for fully integrated gis, image analysis, cad. Understanding difference between coordinate system and. A coordinate system is also used as a reference system to represent locations of geographic features, observation points, gps global positioning system points, and imagery within this framework. To select a map projection, determine which of the properties is the most important for the project, and select the coordinate system or map projection that best preserves that property. Geographic coordinate systems are based on a spheroid and utilize angular units degrees. To change the gis coordinate system autocad autodesk. Working with map projections and coordinate systems in. State plane coordinate system spcsstate plane coordinate system spcs beggppjan in 1930s for public works projects states divided into 1 or more zones total for us fivezonesfortexasfive zones for texas different projections used.
The gcs tells your data where to draw on the earth, and the projection tells the map how to distort the earth onto a flat surface. The map of massachusetts in unprojected decimal degrees of longitude and latitude note the proportion of the lines and the circle. Map projections and coordinate systems the university of maine. If projection does not document the datum, it may be irreversible. Most gis packages create metadata files that establish. If the first layer does not have a coordinate system, arcmap will set the coordinate system to unknown. Area of use values are in decimal degrees based upon wgs. Although the projection procedure inevitably introduces system.
It is usually defined by a map projection, a spheroid of reference, a datum, one or more standard parallels, a central meridian, and possible shifts in the x and y. Map projections and coordinate systems gis courses. You can choose coordinate reference system parameters in tntmips when you establish georeference control for your project materials, when you import georeferenced data, or when. This is different from defining a projection for data. A coordinate system, datum, and map projection are all components of. Coordinate systems enable geographic datasets to use common locations for integration. Universal transverse mercator utm coordinate system cylindrical conformal true scale along central meridian, which points at geographic north, or along two lines equidistant from the central meridian which do not point at geographic north. Identifying the coordinate system typegeographic or projected. Together, these two concepts form the basis for a coordinate system. The ncrs was originally intended to be one map projectioncoordinate system for the entire city. 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. The output dataset or feature class field should be statesproject. Unlike a geographic coordinate system, a projected coordinate system has constant lengths, angles, and areas across the two dimensions.
The employed plane coordinate system is either projected or geographic. Qgis starts each new project using the global default projection. A projected coordinate system is always based on a geographic coordinate system that is based on a sphere or spheroid. Polar coordinates are twodimensional and thus they can be used only where point positions lie on a single twodimensional plane. The decision as to which map projection and coordinate reference system to use. A projected coordinate system is based on a geographic coordinate system and a map projection. The longitude value differs by about three seconds. Project the globe onto a 2d surface there are lots of ways to do each step, resulting in lots of coordinate reference systems. A horizontal datum is defined by an ellipsoid, and its fixation with respect to the surface of the earth. A coordinate system is a reference system used to measure horizontal and vertical distances on a planimetric map. And to be displayed on the same map, your data doesnt need to be stored in the same coordinate system.
Polar coordinate system gis wiki the gis encyclopedia. Within arcgis, every dataset has a coordinate system which is used to integrate it. Get up and running with arcgis, a true geographic information system gis that allows you to dig into highly accurate geospatial data in a way other mapping applications cant compete with. The transverse mercator map projection is an adaptation of the standard mercator projection which flips the cylinder 90 degrees transverse. A coordinate reference system crs then defines, with the help of coordinates, how the twodimensional, projected map in your gis is related to real places on the earth. An introduction to projections arcgis basics coursera. Utm grid zones map of the world overlayed with utm grids. Although gis features are a model of realworld features existing on an oval surface, their positional references, i. Choosing the right data frame coordinate systems in arcgis mike pesses, antelope valley college the data frame of an arcgis mapping project can use any predefined or custom coordinate system to display data in an attractive way. It is normally used in preparing maps and making linear measurements.
The universal transverse mercator system is a specialized application of the transverse mercator projection. Under the spatial reference section, scroll down and notice that both a geographic coordinate system and a projection are listed, which indicates that the coordinate system of this feature class has already been defined. Dec 03, 2011 this application reprojects the coordinates of a point from one system to another. A geographic coordinate system is a coordinate system that enables every location on earth to be specified by a set of numbers, letters or symbols. How universal transverse mercator utm works gis geography. Under related information below, click the link titled projections table 2009 to access. I have a screenshot of the projection files that show what we are projecting from and to. Note that the geographic coordinate system is gcs north american 1983. Working with map projections and coordinate systems in arcgis. May 02, 2011 working with map projections and coordinate systems in arcgis mahmoud abdelrahman. A tutorial on map projections and geographic coordinate systems. Follow these steps to figure out what geographic coordinate system and. This default can be changed via the select crs button in the first section, which is used to define the default coordinate reference system for new projects, as shown. Jan 05, 2019 projected coordinate system makes use of 2dimensional or flat plane surface representing earth surface objects.
Its usually done from a geographic coordinate system, which in turn uses a datum as its base definition. A coordinate system is a reference system used to represent the locations of geographic features, imagery, and observations, such as global positioning system gps locations, within a common geographic framework. In the data source section, there should be a label that says geographic coordinate system or projected coordinate system. Heres the same point on the north american datum of 1927 nad 1927 or nad27. Right click on the title of your map layer in the table of contents of arcmap. Introduction to coordinate systems and projections gis. Introduction to coordinate systems and projections gisdata. It is sometimes referred as gausskruger coordinate system in other countries. The other is when data are encoded for the purposes of spatial analysis or overlaying with other data. Gis data sets will have a defined geographic coordinate system, but may not have a defined projection.
Projected coordinate system continental north america usa contiguous lambert conformal conic. Select a suitable map projection or coordinate system. Geographic information system proandroid pdf gis softwares. Geol 3050 gis for geologists exercise 5 exercise 5. Working with map projections and coordinate systems in arcgis mahmoud abdelrahman. Coordinate systems, projections, and transformations. A coordinate system, datum, and map projection are all components of the coordinate reference system for a spatial object. A projection is the means by which you display the coordinate system and your data on a flat surface, such as a piece of paper or a digital screen. Projected coordinate systems are based on a plane the spheroid projected onto a 2d surface and utilize linear units feet, meters, etc.
Other measurement system properties such as a spheroid of reference, a datum, and projection parameters like one or more standard parallels, a central meridian, and possible shifts in the x and ydirections. In one gis project or database, all layers should have the same coordinate system we need to do conversions arctoolbox has full functions to do this conversion of projection, datum, coordinate system 44 45. The circle gives the impression that worcester is approximately the same distance from boston as new hampshire, and that the state is nearly five times longer, east to west, as it is northtosouth. The coordinates are often chosen such that one of the numbers represents a vertical position and two or three of the numbers represent a horizontal position. There are two situations in which a person may need to declare a geographic coordinate system and or a projection. Follow these steps to figure out what geographic coordinate system and projection a dataset or layer is using. Area of use values are in decimal degrees based upon wgs 1984. Project a feature class from a geographic to a projected coordinate system task 2. The following are two common types of coordinate systems used in a geographic information system gis a global or spherical coordinate system such as. The definition of the map projection for projected coordinate systems. The map projection contains the mathematical calculations that convert the geodetic locations to the planar system. The signs of x,y coordinates in a projected coordinate system. Reproject wgs 1984 to utm nad 1983 zone 17 with geographic transformation basics duration.
This pdf file lists map projections supported in arcgis desktop version 10. When you assign a geographic location to a drawing file, you also assign gis coordinate system to it. A coordinate system is a reference system used to represent the locations of geographic features, imagery, and observations, such as global positioning system gps locations, within a. Mathematical calculations are used to convert the coordinate system used on the curved surface of earth to one for a flat surface. Gis data is created in one of two types of coordinate systems. Arcmap changing or transforming a coordinate system for.
It is recommended and required on any survey performed for the city to include a coordinate definition statement with the basis of bearings whenever coordinates are shown. Lecture 2 map projections and gis coordinate systems. Nevada coordinate reference system ncrs overview general information. A projected coordinate system is a planar system that uses twodimensional coordinates and linear distance measurements as units. Universal transverse mercator utm coordinate system.
463 768 1064 271 114 247 1379 259 79 1206 939 802 414 382 1307 88 674 269 1347 281 579 328 416 1555 900 1158 1307 914 881 390 904 781 1376 984