Xian80 to CGCS2000 Converter
About Xian80 Coordinate System
Xi'an 80 (Xian1980, Chinese Geodetic Datum 1980) is a Chinese national geodetic datum established in the 1980s. It uses the IAG75 ellipsoid (a=6378140m, 1/f=298.257) and employs a 7-parameter Helmert transformation from WGS84. It is widely used in Chinese surveying and mapping alongside BJ54 and CGCS2000.
Xi'an 80 was established in the 1980s as China's second national geodetic datum, replacing the earlier BJ54 system. It improved accuracy by using the IAG75 ellipsoid and a more precise geoid model, providing a unified reference for national mapping and infrastructure projects.
Xi'an 80 is widely used in Chinese surveying, mapping, and GIS applications, particularly in legacy data and regional projects. While CGCS2000 is the modern standard, large volumes of spatial data remain in Xi'an 80 and conversion between these systems is commonly required.
Xi'an 80 is an official Chinese national geodetic datum, used extensively in legacy surveying, mapping, and infrastructure data.
Xi'an 80 uses the IAG75 ellipsoid (a=6378140m, 1/f=298.257), the same as the IUGG 1975/IAU 1976 recommended values.
About CGCS2000 Coordinate System
CGCS2000 (China Geodetic Coordinate System 2000) is China's official national geodetic coordinate system, replacing Beijing 1954 and Xian 1980 systems. It is aligned with ITRF97.
CGCS2000 was officially adopted by the State Council of China in 2008 as the national standard.
CGCS2000 is mandatory for all official surveying, mapping, and GIS projects in China. It is used by government agencies, land management, urban planning, and infrastructure development.
CGCS2000 is aligned with the International Terrestrial Reference Frame 1997 (ITRF97) at epoch 2000.0.
CGCS2000 and WGS84 are essentially identical for most practical applications, with differences typically less than 1 meter.
CGCS2000 is supported by a nationwide network of continuously operating reference stations (CORS) across China.
⚙️ 7-Parameter Helmert Transformation Guide
The 7-parameter Helmert transformation (also known as the time-tested similarity transformation / 3D conformal transformation) is the standard geodetic method for converting coordinates between two different datums. It applies three translations (dx, dy, dz), three rotations (rx, ry, rz), and one scale factor (s) to transform coordinates from one reference frame to another. This method preserves shapes (conformal) while shifting and rotating the entire coordinate system in 3D space.
Xian80 uses a different ellipsoid and reference frame than CGCS2000. To bridge this difference, a 7-parameter transformation is required. Unlike simpler methods such as geocentric translation (3-parameter) or Molodensky transformation, the 7-parameter Helmert provides the highest accuracy by accounting for all spatial differences between the two datums, including axis rotations and scale variations. The parameters must be sourced from local surveying authorities or geodetic organizations.
Translation Parameters
dx, dy, dz (meters) - shifts along X, Y, Z axes of the Earth-centered reference frame
Rotation Parameters
rx, ry, rz (radians) - rotations around each axis to align datum orientations
Scale Parameter
s (ppm) - scale factor adjusting for size differences between ellipsoids
# Example parameters for Xian80 to WGS84 # These are REGIONAL approximations — use official values for precise work. dx = 0 # X-axis shift (meters) dy = 0 # Y-axis shift (meters) dz = 0 # Z-axis shift (meters) rx = 0 # X-axis rotation (arcseconds) ry = 0 # Y-axis rotation (arcseconds) rz = 0 # Z-axis rotation (arcseconds) s = 0 # Scale factor (ppm) # 💡 For Xian80 → CGCS2000, enter the 7 parameters # provided by your national surveying authority for the most accurate results.
⚠️ Important: 7-parameter values are region-dependent. Using parameters from a different region than your coordinate data will result in increased positional errors. Always obtain official parameters from your local surveying authority (e.g., NGII for Korea, Geoscience Australia, Ordnance Survey for UK, etc.).
Xian80 to CGCS2000 Conversion Guide
// Xian80 → CGCS2000 (via WGS84 intermediate)
// Most non-WGS84 conversions use a two-step process:
// Step 1: Xian80 → WGS84 (using reverse transformation)
// Step 2: WGS84 → CGCS2000 (using forward transformation)
// This ensures maximum accuracy by routing through
// the well-defined global WGS84 reference system
// rather than attempting a direct transformationXian80 to CGCS2000 is performed via a two-step transformation through WGS84 as an intermediate reference system, ensuring maximum accuracy.
- Enter your Xian80 coordinates in the input field (latitude, longitude, one pair per line)
- Click the Convert button to transform coordinates from Xian80 to CGCS2000
- Review the converted CGCS2000 coordinates in the output field
- Copy the results or save them as an XLSX file for further use
- Ensure coordinates are within valid ranges before conversion
- For batch conversions, enter one coordinate pair per line
- Verify a sample of converted coordinates on your target platform
- All conversions are performed client-side for complete data privacy