Nirengi

Nirengi is a classical positioning method used in cartography, geodesy, and engineering sciences to represent an area through measurements. In this method, a specific number of fixed points are established on the terrain, and these points are connected in a network structure based on the geometric principle of triangulation. The relative positions and angles of these fixed points, known as nirengi points, allow unknown distances to be calculated. Theoretically, this technique enables the determination of other points through trigonometric calculations, starting from a triangle with one known side and the angles at its endpoints. Thus, high-accuracy results can be obtained without the need for direct distance measurements over large areas.

Nirengi networks are established on fixed reference points called nirengi points. These points are typically visible on the terrain and represented by permanent structures such as concrete blocks, stone pillars, towers, or minarets of churches or mosques. Each nirengi point is precisely located within a specific coordinate system, usually in the horizontal plane. The linear distances and angular measurements between these points allow the positions of all other points in the network to be calculated. The nirengi network is the drawing that shows these points on a map. The network diagram indicates how the triangles are formed, how the points are interconnected, and the overall configuration of the network. A nirengi network generally consists of a primary network and subordinate networks that densify it. For the triangulation process to be reliable, the network must have a robust geometric structure and minimize error propagation.

The nirengi method gained widespread use with the development of modern cartographic techniques in the 18th century and was adopted by states during the 19th and 20th centuries as the foundation of national mapping systems. This technique was regarded as the most reliable method for land surveying before the advent of satellite systems. In Türkiye, this method was also used for many years to establish fundamental horizontal control networks.

From the 1970s onward, various efforts were initiated in Türkiye to enhance the precision of nirengi networks. These included coordinate validation through astronomical observations, determination of side lengths using electronic measuring devices, and network re-adjustment studies. In particular, micro-geodetic networks were established to monitor post-earthquake deformations, extending the use of nirengi points beyond cartography to earth sciences. With the development of Doppler systems in the 1980s and beyond, the integration of GPS technology into geodesy, and the widespread adoption of global coordinate systems, classical nirengi methods were gradually replaced by more modern techniques. However, the nirengi networks established from the past to the present continue to serve as foundational data sources that underpin these new technologies.

Nirengi serves as a reference positioning tool in many technical disciplines:

• Cartography and cadastre: accurate and reliable determination of coordinates of locations on the terrain,
• Civil engineering projects: position control, especially in large-scale infrastructure projects,
• Maritime navigation: direction determination using coastal nirengi points as references,
• Geology and earthquake engineering: monitoring crustal movements and deformation analysis.

Even with the widespread adoption of GPS and satellite technologies, nirengi points are still used in many areas for calibrating and comparing local measurement systems.

Modern technological advances, particularly the proliferation of GNSS (Global Navigation Satellite Systems)-based measurement systems, have reduced the direct field use of classical nirengi methods. However, fixed reference points are still required to calibrate and control these systems. Therefore, existing nirengi networks continue to play a vital role as validation and support infrastructure for GPS/RTK and similar systems. Moreover, in some rural areas where satellite signals are insufficient or in engineering projects requiring high precision, classical methods based on fixed nirengi points are still preferred.