Instructions
Used to compute the minimum bounding geometry of a single closed object or a group of objects, and output the feature data set of the polygon objects (FeatureRDD). Supports the calculation of the following five types of minimum bounding geometries:
- Minimum bounding rectangle: the rectangle with the minimum width that encloses the input object
- Minimum area rectangle: the rectangle with the minimum area that encloses the input object
- Convex hull: the minimum convex polygon that encloses the input object
- Minimum enclosing circle: the minimum circular boundary that encloses the input object
- Envelope rectangle: the minimum external rectangle parallel to the coordinate axis of the input object
| Source data set | Minimum bounding rectangle | Minimum area rectangle | Convex hull | Minimum enclosing circle | Envelope rectangle |
|---|---|---|---|---|---|
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Parameter description
| Parameter | Description | Type |
|---|---|---|
| Input feature data set | The point, line, or polygon feature data set to be computed. Usually connected with the "Read Vector Data" tool to obtain input data. | FeatureRDD |
| Grouping field | Specify the grouping field name. The geometric objects with the same field value will be grouped and the minimum bounding geometry will be computed for each group. This parameter is required only when the group option is selected as "Grouping". | String |
| Group option | Specify the grouping method for the input data: - Each feature: The minimum bounding geometry is computed independently for each geometric object. - Grouping: The geometric objects are grouped according to the field values, and the minimum bounding geometry is computed for each group. The attribute values of the grouping field will be preserved in the output polygon objects. - All: All geometric objects in the data set are grouped and only one minimum bounding geometry is outputted. |
String |
| Minimum bounding geometry type | Specify the desired type of minimum bounding geometry, supporting the selection of minimum bounding rectangle, minimum area rectangle, convex hull, minimum enclosing circle, and envelope rectangle. | String |
Output results
| Parameter | Description | Type |
|---|---|---|
| Minimum bounding geometry data set | The feature data set containing the computed minimum bounding geometry. The calculation result of the distributed analysis tool is stored in memory and needs to be written out to the database or local file by connecting to the "Save Vector Data" tool. | FeatureRDD |
Application example
Pollution source identification and analysis: The minimum bounding geometry tool can be used to determine the minimum bounding range of pollution sources, which is crucial for identifying and analyzing the spatial distribution of pollution sources. For example, in the study of the temporal and spatial evolution of total nitrogen surface source pollution load in a watershed, the minimum bounding circle of the total nitrogen pollution load center of each surface source pollution source can be calculated using the minimum bounding geometry tool, thereby determining the key identification areas for the variation of the total nitrogen pollution load of each pollution source.
Considerations
The creation of minimum bounding boundaries for point data sets is not supported. When the input data is a point data set and the group option is "Each feature", an exception will occur.
Special handling of point data sets:
(1) When there is only one point or multiple overlapping points in the point data set or group, when calculating the minimum enclosing circle, a circle with a diameter of 10^-6 units of the current data set length will be outputted; when calculating the minimum area rectangle, minimum bounding rectangle, convex hull, and envelope rectangle, a square with a side length of 10^-6 units of the current data set length will be generated.
(2) When there are only two point objects in the point data set or group, for the convex hull, minimum bounding rectangle, minimum area rectangle, and envelope rectangle (the envelope rectangle is only applicable when the line features are horizontal or vertical), a rectangle with a width equal to the length of the line segment formed by the two points divided by 100 will be generated.
Special handling of line data sets:
When there is only one straight line or multiple straight lines in the line data set or group, for the convex hull, minimum bounding rectangle, minimum area rectangle, and envelope rectangle (the envelope rectangle is only applicable when the line features are horizontal or vertical), a rectangle with a width equal to the length of the line segment divided by 100 will be generated.
When the input data set is empty, an empty result data set with an object count of 0 will be outputted.
When there are objects in the input data set whose Geometry is empty, these objects will be ignored during calculation, and only the objects with non-empty Geometry will be used to create the minimum bounding geometry.