SECTION 4 PARCEL IDENTIFIERS 4.1 LONGITUDE AND LATITUDE

SECTION 4 PARCEL IDENTIFIERS 4.1 LONGITUDE AND LATITUDE Most maps must be drawn in such a way that points and areas can be located accurately on the earth's surface and described objectively. A uniform locational system made exploration and mapping of the earth possible. The most commonly used locational system for large areas is the geographic grid----latitude and longitude. Because the earth rotates, the axis of rotation intersects the spheroidal surface of the earth at two natural reference points, the poles. The equator is an imaginary line halfway between the poles, separating the earth into a northern and a southern hemisphere. Latitude is the distance in degrees of arc measured north and south of the equator. Lines of latitude, called parallels, run east and west and measure distance north and south. The equator is zero degrees latitude, the north pole is ninety degrees north latitude and the south pole is ninety degrees south latitude. There is no natural reference point for the east/west component of the geographic grid, longitude. In 1884, however, an international conference agreed that an imaginary line extending from the North Pole to the South Pole and passing through the Greenwich Observatory (near London) would be the zero degree meridian of longitude, called the prime meridian. Longitude is measured in degrees of arc east and west of the prime meridian. Meridians are north-south imaginary lines extending from pole to pole. The 180 degree meridian is called the International Date Line. 4-1

4.2 STATE PLANE COORDINATE SYSTEM Because the earth's surface is curved and irregular, it was necessary to develop a projection to cover the area that would provide a plane surface for surveyors and property mappers. Such a system had to provide a common datum, an assumed plane, for referencing the horizontal control of all surveys. The United States Coast and Geodetic Survey fulfilled this need by developing a state plan coordinate system for each state. A rectangular grid was created and superimposed on the plane surface and the positions of points in the plane located by means of X and Y coordinates. Two projections are used in the United States for state plane coordinate systems: The Lambert Conformal Conic Projection and the Transverse Mercator Projection. North Carolina uses the Lambert Conformal Conic Projection system. 4.3 PARCEL IDENTIFICATION NUMBER Parcel identification numbers are based upon the North Carolina State Plane Coordinate system. They are composed of an X, or east-west, designation and a Y, or north-south, designation. The location of a single point is thus defined. Although the exact center of a parcel can be determined by computer, the identification point for each parcel is usually the approximate center, or paracentroid, of the parcel. 4-2

The following steps should be followed when assigning a parcel identification number (PIN): After establishing the visual center, centroid, of the parcel read the geographic coordinate values using a manual scale or computerized digitizer. Fourteen digits are necessary - 7 east/west (x axis) and 7 north/south (y axis). "X" coordinate (easting) E 2,715,569 "Y" coordinate (northing) N 0,756,737 The digits in coordinate value are paired by taking each digit separately from the east coordinate and matching it with the corresponding digit of the north 20 77 15 56 57 63 97 EN EN EN EN EN EN EN With the arrangement, the above example of a parcel identifier may be sorted as follows: 20 7715 56 5763 97 Redundant Number of Block Lot or Utilized only to lead number basic map number parcel extend the for any one module number capacity of county* ( 1" =400') system The North Carolina "Parcel Identifier Number" or "PIN" is obtained by recording the middle three sets of numbers (ten digits) and is written with dashes as follows: 7715-56-5763 Condominiums or other cases of diverse ownership on one parcel of land will be further identified by the use of a decimal at the end of the PIN with three (3) digits to the right of the decimal. The record for a condominium unit or units built on the above parcel could be assigned a suffix number to the PIN of.001 through.999. For example, a condominium unit could have the following PIN:7715-56-5763.008. *not redundant in jurisdictions where a million mark is reached. 4-3

The following steps create a parcel identification number (PIN): 1. Establish the visual center, or centroid of the parcel (this calculation is now calculated by the GIS software) 2. Read the geographic coordinate values using a scale. 14 digits are required 7 easting and 7 northing. (Note: 6 digit readings are preceded by 0.) NC State Plane is in feet. X coordinate (EASTING) E 1,025,565 feet east of 0 Y coordinate (NORTHING) N 0,636,735 feet north of 0 3. Taking each digit separately from the east coordinate and matching it with the corresponding digit of the north coordinate, pair the digits by coordinate value. Remember; EAST FIRST! 10 06 23 56 57 63 55 EN EN EN EN EN EN EN 4. With this arrangement, the above example of a parcel identifier may be sorted as follows: 10 0623 56 5763-55 Note: although most tax systems will only store the center 10 digits as the PIN, to have a truly unique PIN across the NC state plane, the lead # or millions makes the PIN unique. This was extremely important for counties who had a million mark grid when this geographic data was stored in a tabular database. This allowed the capability to perform radial (geographic) queries. Geographic Information systems have eliminated this need to store the millions lead numbers. Millions 10 Thousands & 100 Thousands Thousands Hundreds & Tens - MAP - BLOCK - LOT - 10-0623 - 56-5763 - 55 Lead number. Will change when a million mark in reached Number of basic map module (1 =400 ) Block number Lot number, centroid of parcel Ones To extend the capacity of the system i.e.: manufactured homes* 4-4

PARCEL IDENTIFICATION NUMBER WORKSHEET 1. East,, 2. + 3. E,, 1. Read the easting or X coordinate from the top or bottom margin of the map, this reading is taken from the west side of the block of where the pin dot lies. enter the number here, right adjusted, any remaining spaces on the left can be padded with 0 s as place holders. 2. Using your scale measure the distance in feet from the west line of the block over to the pin dot. This reading can be to the nearest 10 th. Enter the result. 3. Add the two measurements together. The result is an easting or X 4. North,, 5. + 6. N,, 4. Now read the northing or Y coordinate from the left or right margin of the map. This reading is taken from the south line of the block that the pin dot is in. Remember to right adjust your reading and pad the left with 0 s. 5. Using your scale measure the distance in feet from the south line of the block up to the pin dot. This reading can be to the nearest 10 th. Enter the result here. 6. Add the two measurements together. The result is a northing or Y 7. E,, 8. X,, 100 10 One Millions Thousands Thousands Hundreds Tens Ones 7. & 8.. Rewrite the East and North measurements here. Remember these are measurements in feet from the point of origin (0,0), for North Carolina the point of origin is in Tennessee! 9. - - - - 9. To make a PIN, the numbers are put together every other one starting with the EAST or X To remember which one comes first, X or Y or East or North, remember they are always in alphabetical order, East (X) first then North (Y). Write the 14 digit PIN here from left to right alternating from top to bottom always starting with the million digit of the east or X - - - - 4-5

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