Calculate Geodesic Area
Overview
The Calculate Geodesic Area tool is designed for high-accuracy area statistics. It uses the earth ellipsoid, WGS 84 by default, as the datum surface to calculate the actual surface-projected area of polygon features. Compared with traditional planar area calculations, it effectively reduces area distortion introduced by map projections and provides more reliable results, especially across large geographic extents or when using a geographic coordinate system with longitude and latitude.
Use Cases
- Territorial spatial planning: Calculate accurate areas for large administrative regions or ecological protection redlines.
- Carbon sink and forest resource surveys: Calculate the true surface-projected area of vegetation cover across regions spanning a wide range of latitudes.
- Aerospace thematic analysis: Calculate mission coverage areas at intercontinental scales.
Parameters
| Parameter | Description | Notes |
|---|---|---|
| Input features | The polygon feature dataset for which area will be calculated. | Must be polygon features. |
| Area field name | The field name used to store the area calculation result. | Default: area_m2. |
| Output feature dataset | The output result containing the area field. | Supports common vector formats. |
Steps
- Start the tool: Open the Geoprocessing Toolbox, go to Vector tools > Feature calculation, and open the Calculate Geodesic Area tool pane.
- Set the input: Select the Input features to process.
- Configure parameters: Set the Area field name.
- Configure the output: Set the output path and file name.
- Run the tool: Click Run and review the result.
Notes
- Geodesic calculation results are usually in square meters (m²). To convert the result to mu or hectares, use the Calculate Fields tool afterward for unit conversion.
- If the input data has an incorrect coordinate system definition, such as projected coordinates marked as longitude and latitude, the calculation result will have significant errors.
- This tool automatically handles holes, or inner rings, inside polygon features and outputs the net area. iXGIS recommends running Repair Geometry before calculation.