# Lat long Converter

## 1. Coordinate Picker Tools

- AMap Coordinate Picker: https://lbs.amap.com/tools/picker
- Baidu Coordinate Picker: https://api.map.baidu.com/lbsapi/getpoint/
- Tencent Coordinate Picker: https://lbs.qq.com/getPoint/
- Google Maps Coordinate Picker (Right-click): https://www.google.com/maps/

## 2. Supported Map Coordinate System Conversions

- Single coordinate conversion.
- Batch coordinate conversion, up to 100,000 entries.
- UTM to WGS84 or WGS84 to UTM uses 6-degree zones by default, 3-degree zones are not supported.

## 3. Introduction to Five Coordinate Systems

### 3.1 WGS84

WGS84 (World Geodetic System 1984) is the geodetic system and Earth reference framework used by the Global Positioning System (GPS). Developed by the U.S. Department of Defense, it is widely used in navigation, mapping, and Geographic Information Systems (GIS). Here are some key details about the WGS84 coordinate system:

3.1.1 Ellipsoid Parameters: - Semi-major axis (a): 6378137.0 meters - Inverse flattening (1/f): 298.257223563 - Semi-minor axis (b): 6356752.3142 meters 3.1.2 Origin: - The origin is at the Earth's center of mass, at the intersection of the equator and prime meridian. 3.1.3 Coordinate System: - Longitude: Measured east or west from the prime meridian, ranging from -180° to +180°. - Latitude: Measured north or south from the equator, ranging from -90° to +90°. - Elevation: Height relative to the ellipsoid surface.

### 3.2 GCJ02

GCJ-02 (Mars Coordinate System) is a geodetic system developed by the Chinese National Bureau of Surveying and Mapping, used for geospatial data within mainland China. Here are some key details about the GCJ-02 coordinate system:

3.2.1 Ellipsoid Parameters: - GCJ-02 uses the same ellipsoid parameters as WGS84, based on the Earth's ellipsoid model. 3.2.2 Offset Algorithm: - The GCJ-02 system applies encryption and offset processing to the WGS84 coordinates to ensure national geospatial data security. - The offset algorithm is confidential and not publicly disclosed, but various methods exist for conversion in development.

### 3.3 BD09

BD-09 (Baidu Coordinate System) is a geodetic system developed by Baidu, based on GCJ-02 (Mars Coordinate System) with further encryption and offset processing. It is widely used in Baidu Maps, Baidu Navigation, and other Baidu geospatial services. Here are some key details about the BD-09 coordinate system:

3.3.1 BD-09 Coordinate System: - BD-09 is derived from the GCJ-02 coordinate system through additional offset processing. - The system applies encryption algorithms to the original coordinates to protect geospatial data security. 3.3.2 Offset Algorithm: - The specific encryption algorithm of BD-09 is not publicly disclosed, but third-party implementations and reverse engineering results are available.

### 3.4 CGCS2000

CGCS2000 (China Geodetic Coordinate System 2000) is the national geodetic system of China, established by the National Administration of Surveying, Mapping and Geoinformation (NASG). It is widely used in national surveying, GIS, and navigation. Here are some key details about the CGCS2000 coordinate system:

3.4.1 Reference Ellipsoid Parameters: - Semi-major axis (a): 6378137.0 meters - Inverse flattening (1/f): 298.257222101 - Gravitational constant GM: 3.986004418×10^14 m^3s^-2 - Angular velocity ω: 7.292115×10^-5 rad s^-1 3.4.2 Origin: - The origin is at the Earth's center of mass, referenced to the International Terrestrial Reference Frame (ITRF). 3.4.3 Coordinate System: - Longitude: Measured east or west from the prime meridian, ranging from -180° to +180°. - Latitude: Measured north or south from the equator, ranging from -90° to +90°. - Elevation: Height relative to the ellipsoid surface.

### 3.5 UTM（Universal Transverse Mercator）

The UTM (Universal Transverse Mercator) coordinate system is a geographic coordinate system based on the transverse Mercator projection, dividing the Earth's surface into multiple projection zones, each covering 6 degrees of longitude. The UTM coordinate system uses meters to represent geographical locations.

3.5.1 Features of the UTM Coordinate System 3.5.1.1 Partitioning: - The Earth's surface is divided into 60 longitudinal zones, each 6 degrees of longitude wide. - Zone numbers start from 180 degrees west longitude, numbered from 1 to 60. - Each zone is further divided into the northern and southern hemispheres. 3.5.1.2 Coordinate Representation: - Easting: Measured in meters from the central meridian of the zone, with the central meridian's easting usually set to 500,000 meters to avoid negative values. - Northing: Measured in meters from the equator, northwards in the northern hemisphere and southwards in the southern hemisphere, with the equator's northing set to 10,000,000 meters in the southern hemisphere to avoid negative values. 3.5.2 UTM Coordinate Format 3.5.2.1 A typical UTM coordinate consists of the following parts: - Easting: Measured in meters from the central meridian of the zone. - Northing: Measured in meters from the equator. - Zone Number: Represents the range of longitude, from 1 to 60. - Zone Letter: Represents the range of latitude, from C to X (excluding I and O), with each letter zone covering 8 degrees of latitude. 3.5.2.2 Example: For example, here is a UTM coordinate: - Easting: 500,000 meters - Northing: 4,649,776 meters - Zone Number: 33 - Zone Letter: T

## 4. Latitude and Longitude Format Description

### 4.1 DMS (Degrees Minutes Seconds) Format

DMS format represents latitude and longitude in degrees, minutes, and seconds. For example: **Latitude: 40°26'46''N****Longitude: 79°58'56''W**

Here, 40° represents 40 degrees, 26' represents 26 minutes, and 46'' represents 46 seconds. The final character is the direction parameter, where longitude direction can be E (East) or W (West), and latitude direction can be N (North) or S (South).

DMS format is more suitable for use in paper maps or navigation.

### 4.2 Decimal Format

Decimal format represents latitude and longitude in decimal numbers. For example: **Latitude: 40.446****Longitude: -79.982**

Here, -79.982 represents the degrees of longitude, and 40.446 represents the degrees of latitude.

Decimal format is more suitable for use in computer and GIS systems.