Feature Description
Used to compute the geometric properties of a vector dataset, such as geodesic perimeter, geodesic area, node count, and center coordinates. The calculation results will be directly updated to the source dataset, and support selecting existing fields or new fields for storage.
Supports computing multiple types of geometric properties, as detailed below:
Center coordinates (X/Y): Calculate the center position based on the shape of the geometry, divided into two attributes: CenterPointCoordinate_X and CenterPointCoordinate_Y.
Centroid coordinates (X/Y): Compute the centroid by calculating the weighted mean of the coordinates of each part of the geometry, divided into two attributes: CentroidCoordinate_X and CentroidCoordinate_Y.
Geodesic area: As a calculation method for ellipsoidal area, it focuses on using geodesics (i.e., the shortest connections between two points on the Earth's ellipsoid surface) as boundaries to calculate the area.
- For geographic coordinate systems, the original algorithm has been optimized to compute more accurate geodesic areas. After optimization, the algorithm effectively reduces the impact of Earth's curvature on the calculation results, thereby improving the accuracy of area computation;
- For Gauss_Kruger (Xian 1980) and Gauss_Kruger (CGCS2000) coordinate systems, compute the precise ellipsoidal area according to the Gaussian coordinate inverse calculation formula provided in the "Third National Land Survey Technical Regulations";
- For other projected coordinate systems and planar coordinate systems, directly compute the planar area.
Geodesic perimeter: The geodesic perimeter of polygon objects or the geodesic length of line objects.
- For geographic coordinate systems, the geodesic perimeter is the same as the default SmPerimeter of the surface.
- For projected coordinate systems and planar coordinate systems, the geodesic perimeter is the same as the default SmPerimeter of the object. To compute a geodesic perimeter with practical significance, it is necessary to convert to a geographic coordinate system for computation.
Area: The planar area of polygon objects, computed directly using x and y coordinate values.
Perimeter: The perimeter of line and polygon objects, computed directly using x and y coordinate values.
Subobject count: The number of subobjects contained in the geometry.
Node count: The node count of line objects or polygon objects.
Bound coordinates: Divided into four attributes: maximum and minimum values of x and y coordinates.
Line start point: Divided into two attributes: LineStartPoint_X and LineStartPoint_Y.
Line center point: Divided into two attributes: LineCenterPoint_X and LineCenterPoint_Y.
Line end point: Divided into two attributes: LineEndPoint_X and LineEndPoint_Y.
Line azimuth: The azimuth of line objects.
Hole counts: The number of holes in polygon objects.
Parameter Description
| Parameter Name | Parameter Interpretation | Parameter Type |
|---|---|---|
| Source Dataset | The input vector surface dataset. | DatasetVector |
| Field (existing or new): | Specify a field to store the calculation results, supporting the specification of existing fields or new fields. If an existing field name is filled in, the current field value will be overwritten by the calculation results; if a new field name is filled in, a new field will be added to save the calculation results. | String |
| Geometry Property: | Select the geometric properties to add or update. Supports adding multiple geometric properties, and the added multiple geometric properties need to correspond one-to-one with the fields. | GeometryPropertyType |
| Length Unit: (Optional) |
Specify the calculation unit for perimeter computation, providing 9 common units of length such as centimeter, decimeter, meter, kilometer, inch, foot, mile, etc. | Unit |
| Area Unit: (Optional) |
Specify the calculation unit for area computation, providing 14 common units of area such as cm², dm², square meter, km², hectare, are, etc. | AreaUnit |
| Coordinate: (Optional) |
Specify the coordinate system consistent with the geometry. When the dataset's coordinate system is incorrect, the correct coordinate system can be specified through this parameter. | PrjCoordSys |
Output Result
| Parameter Name | Parameter Interpretation | Parameter Type |
|---|---|---|
| Result Dataset | The result dataset. | DatasetVector |
Considerations
Function Changes 1. Since SuperMap 11i (2024) version, the algorithms for "ellipsoidal area" and "geodesic area" have been improved and integrated. Therefore, the "ellipsoidal area" option in geometric properties has been removed. To obtain more accurate area calculation results, please select "geodesic area" for computation. If your model was set to compute "ellipsoidal area" in older versions, after importing the model in the new version, the geometric properties parameter will automatically change to "geodesic area".
2. Since SuperMap 12i (2025) version, the geometric properties parameter has added "Area" and "Perimeter" options, which can directly compute the geometric area and perimeter of the input data. It should be noted that when the dataset's target coordinate system is a geographic coordinate system, the computed "Area" and "Perimeter" results are merely numerical values without practical physical significance. Therefore, converting results by changing calculation units is invalid; to obtain results with actual units, please first project the data to an appropriate planar coordinate system.