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SAD69 coordinate system is the abbreviation of South American Datum 1969, which is a geodetic reference system widely used in South America. It is based on the Krasovsky ellipsoid and established through the astronomical geodetic network data of Brazil, Argentina and other countries. It is mainly used for topographic mapping and geographic information applications in South American countries. This coordinate system has local deformation due to regional gravity field differences and is gradually being replaced by more accurate modern datums such as SIRGAS2000.

Korea 2000 coordinate system is the national plane coordinate system adopted by Korea in 2002. It is based on ITRF97 framework and GRS80 ellipsoid and adopts transverse Mercator projection (central meridian 127°E). It replaced the old Tokyo coordinate system and is compatible with global satellite positioning systems (such as GPS). It has higher accuracy and is widely used in Korea's land surveying and engineering construction.

DGN95 (Datum Geodesi Nasional 1995) is a geographic coordinate reference system officially adopted by the Indonesian government in 1995 and is used as the surveying and geographic information infrastructure throughout Indonesia. Its EPSG code is designated as 4755 and was designed to suit Indonesia's geographic characteristics and geodetic requirements. DGN95 is based on the international geodetic standard ITRF1992 (International Terrestrial Reference Frame 1992) and is the national standard to ensure uniformity in surveying and highly accurate location information.

NZGD2000 (New Zealand Geodetic Datum 2000) is the New Zealand 2000 geodetic datum, which is the current national geodetic coordinate system of New Zealand. It is used to define the reference framework of the country's geospatial data and plays an important role in surveying and mapping, geographic information, engineering and other fields.

A Compound CRS achieves unified representation of multi-dimensional spatial data by combining multiple coordinate reference systems (CRS). For example, it integrates a planar coordinate system (e.g., EPSG:7661) with an elevation system (e.g., EPSG:3855) to form a complete "planar + elevation" spatial description. Its core features include ensuring consistency between horizontal and vertical coordinate systems through associated parameters (such as ellipsoids and datums), making it suitable for fields requiring simultaneous expression of planar positions and elevations, such as terrain modeling and 3D GIS analysis. Technically, a Compound CRS typically comprises a horizontal CRS and a vertical CRS, unified through nested or associated parameters.

UTM Zone (Universal Transverse Mercator Coordinate System) is a coordinate system that converts latitude and longitude coordinates on the Earth's surface into a planar Cartesian coordinate system. It is widely used in map creation, engineering surveying, and military applications. Its core principle involves reducing distortion through zonal projection and achieving high-precision positioning through standardized coordinate representation.

Albers equal-area conic projection is an equal-area conic projection that utilizes two standard parallels. Compared to projections with only one standard parallel, this approach helps reduce distortion to some extent. It is best suited for mapping large continental areas extending predominantly in an east-west direction in the mid-latitudes and is commonly used for maps of the contiguous United States, Europe, and Australia.

Robinson projection is a widely used map projection method developed since the 1960s, designed to represent the entire world on a single map. It seeks a practical compromise for displaying the whole Earth on a flat surface. Introduced in 1963 by Dr. Arthur H. Robinson, this projection features straight latitude lines and evenly spaced meridians, classifying it as a pseudocylindrical projection. While the central meridian is straight, all other meridians are curved. Robinson defined this projection by constructing a lookup table of Cartesian coordinates through specific interpolation of latitudes and longitudes, rather than using mathematical formulas.

**Amersfoort (EPSG:4289) **is a widely used geographic coordinate system in the Netherlands, using Bessel 1841 as the base ellipsoid, with the geodetic base point at Amersfoort. This coordinate system has long played an important role in land surveying, mapping, and infrastructure development in the Netherlands. EPSG:4289 uses geographic coordinates (latitude and longitude), making it suitable for expressing wide-area location information on the Earth’s surface.

JGD2000 is the national surveying system of Japan officially adopted by the Geospatial Information Authority of Japan in April 2002, replacing the previous “Tokyo Datum”. The main purpose of its introduction is to enhance the coordination with the global GPS coordinate system. JGD2000 is based on the geocentric coordinate system (ITRF: International Terrestrial Reference Frame) with the center of the earth as the origin, thus achieving higher-precision measurement and GIS analysis capabilities.