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Technical

Coordinate System

A mathematical reference frame for geographic positions. Turkish cadastral records use UTM and WGS84.

A coordinate system is the mathematical framework that numerically identifies a point's geographical position. In Türkiye's mapping and cadastre practice, two main systems are used: geographic coordinates (latitude-longitude in degrees) and projected coordinates (x-y in metres).

Geographic coordinates give angular position on a spheroidal reference ellipsoid; WGS84 (GPS standard) and ITRF96 (Turkey's National Geodetic Network) are the common reference ellipsoids. Projected coordinates flatten Earth onto a plane, enabling distance and area calculations. Türkiye uses the UTM (Universal Transverse Mercator) projection in 6° zones (35, 36, 37, 38) and Gauss-Krüger in 3° zones.

The cadastre and land registry system stores all parcels in the national reference framework defined by TKGM (typically ITRF96 + UTM). Digital maps and GIS applications exchange data with an SRID (Spatial Reference ID) code (e.g. EPSG:4326 for WGS84 geographic, EPSG:32636 for UTM Zone 36N).

Choosing the wrong coordinate system leads to serious location errors: WGS84 and ED50 for Türkiye can differ by 200-300 m. Platforms like Drozero always store input/output data in WGS84 (EPSG:4326) and perform transformations on demand.

Examples

  • 1.Taksim Square, İstanbul: WGS84 geographic (41.0369°N, 28.9857°E); in UTM Zone 35N projection (410,893 E, 4,545,012 N).
  • 2.A surveying engineer measures in 3° Gauss-Krüger on the ITRF96 datum for a parcel survey; transforms to UTM Zone 36N when uploading to the cadastre system.
  • 3.A drone ortophoto is saved in WGS84/UTM 36N (EPSG:32636) projection and automatically converts to ITRF96 in GIS.

Frequently Asked Questions

What's the difference between WGS84 and ITRF96?expand_more
WGS84 is the US-developed global reference system for GPS; ITRF96 is the 1996 epoch of the international terrestrial reference frame used by Türkiye. Geographic differences are sub-metre; interchangeable for most applications. However, TKGM prefers ITRF96 for cadastral measurements.
How is a UTM Zone chosen?expand_more
Türkiye spans 4 UTM zones: **Zone 35** (26°-32° E, Western Thrace + Aegean coast), **Zone 36** (32°-36° E, Marmara + Central Anatolia), **Zone 37** (36°-40° E, Eastern Anatolia + Mediterranean), **Zone 38** (40°-44° E, GAP region). For parcels on zone boundaries, TKGM uses the local authority's chosen zone; zone information is in map metadata.
What's an EPSG code?expand_more
EPSG (European Petroleum Survey Group) is the world standard numerical identifier for coordinate systems. Examples: EPSG:4326 (WGS84 lat-lon), EPSG:32636 (WGS84 UTM Zone 36N), EPSG:5254 (ITRF96 3° Gauss-Krüger at 33° meridian). GIS and GPS software perform transformations by EPSG codes.
What system does my GPS coordinate use?expand_more
Modern smartphones and GPS devices return **WGS84 geographic coordinates** (lat-lon in decimal degrees) by default. If your device shows UTM or another system, switch to WGS84/lat-lon in settings. For cadastre comparison, seek a platform that delivers coordinates in EPSG:4326 (WGS84).

Related Terms

WGS84 (World Geodetic System 1984)UTM (Universal Transverse Mercator)GIS (Geographic Information System)Orthophoto

Sources

  • • Large-Scale Map and Map Information Production Regulation (BÖHHBÜY)
  • • TKGM National CORS Network (TUSAGA-Aktif) coordinate standards
  • • EPSG Geodetic Parameter Registry (epsg.org)

Try the FAR/GCR calculator

Calculate total floor area, storey count and estimated unit count in seconds from parcel m² and zoning values.

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Last updated: 2026-04-24