Qatar National Grid (QND95)

surveyingQND95 is a two dimensional coordinate reference system that is the standard for geographic mapping in Qatar.  QND95 is intended for onshore activities only. QND95 provides up-to-date specs to calibrate surveying tools, GPS devices, GIS tools, and analysis activity.  The coordinate reference system facilitates standardization and consistency across activities. 

QND95 Coordinates – Eastings and Northings

XY coordinates from a GPS device configured for QND95 are specified using Eastings and Northings, not longitude and latitude.  This is typical of coordinate reference systems that use the Universal Transverse Mercator (UTM) map projection.  An example of GPS coordinates calibrated for QND95 appear below:

The UTM map projection is the most widely used coordinate system for world mapping. All versions have the same basic characteristics and formulas. Differences in UTM maps, such as QND95, arise from variations in the coordinate transformation parameters, namely:

  • The latitude of the origin,
  • The longitude of the origin (central meridian),
  • The scale factor at the origin (on the central meridian), 
  • The values of False Easting and False Northing, and
  • The width of standardized longitudinal zones

Different territories set these parameters differently.  Parameters can be specified in the R programming language using the following syntax or string:

QND95 Parameter Values

The following table defines the values of the coordinate parameters for QND95 that must be plugged into the above string:

These values can be used to calibrate GPS devices, mapping software, and spatial analysis methods.

Converting QND95 to Standard Longitude/Latitude

Since the QND95 map parameters are unique, many standard conversion programs for UTM Eastings and Northings into lon/lat values do not work.  The following R code converts QND95 coordinates to standard lon/lat values in decimal degrees for the WGS84 map projection.  The code relies on the spatial analysis packages rgdal and sp . Conversions to any coordinate reference systems can be done easily enough by simply changing the CRS string in the spTransform command below.  CRS strings must follow the syntax rules of the PROJ4 map library.

The resulting lon/lat coordinates can be accurately used to create data objects in R or to create custom maps.

 

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