Minimum Bounding Geometry
Overview
The Minimum Bounding Geometry tool calculates bounding geometry that encloses the source geometry of input features. It supports per-feature calculation and grouped calculation by one or more fields, where features in each group are merged before the boundary geometry is computed. The output can be used for extent summarization, spatial indexing, cartographic representation, service area estimation, and subsequent spatial analysis.
Supported boundary geometry methods include convex hull, minimum rotated rectangle, minimum enclosing circle, and axis-aligned envelope. Input features can be points, lines, or polygons.
How It Works
The tool first determines the processing granularity based on Group fields:
- If no group field is specified, one boundary geometry is calculated for each input feature, and the feature's non-geometry attributes are retained.
- If group fields are specified, features are grouped by field values. The geometries in each group are merged, and one boundary geometry is calculated for each group. Output attributes mainly include the group fields.
The Calculation method values have the following meanings:
| Method value | Name | Calculation meaning | Typical use |
|---|---|---|---|
convex_hull | Convex hull | Generates the smallest convex polygon that contains all input positions. | Summarize the overall distribution extent. |
min_rot_rect | Minimum rotated rectangle | Generates a bounding rectangle with a small area whose orientation can rotate. | Identify the main direction of a target or create an oriented extent box. |
circle | Minimum enclosing circle | Generates the smallest enclosing circle that contains the geometry. | Represent a service radius, influence area, or coverage area. |
envelope | Axis-aligned envelope | Generates an envelope rectangle parallel to the coordinate axes. | Quickly create rectangular extents, index extents, or tiling extents. |
Use Cases
- Extent summarization and visualization: create concise outlines for building clusters, sample points, road segments, or parcels.
- Spatial statistical unit generation: generate extent geometry for each feature group by administrative area, project ID, batch number, or another field.
- Main direction analysis: use minimum rotated rectangles to identify the primary extension direction of linear or polygonal targets.
- Service area representation: use minimum enclosing circles to summarize the coverage of facility points or facility groups.
- Fast indexing and clipping: use axis-aligned envelopes to generate ranges for later clipping, retrieval, or block processing.
Parameters
| Parameter | Description | Notes |
|---|---|---|
| Input vector file | Source features for which boundary geometry will be generated. | Required. Supports point, line, polygon, and multipart geometry. |
| Group fields | Fields used to group features before calculating boundary geometry. | Optional. Multiple fields are supported. If left empty, the tool calculates per feature rather than summarizing the entire layer. |
| Calculation method | Algorithm used to generate the boundary geometry. | Required. Default: convex_hull. Options: convex_hull, min_rot_rect, circle, and envelope. |
| Output vector file | Output feature dataset containing the boundary geometry. | Required. The coordinate system is inherited from the input features. |
Output
The output is a new vector feature dataset.
When Group fields is not set, the number of output records is usually the same as the number of input records. Each input feature generates one boundary geometry, and input attributes are retained. When Group fields is set, each group outputs one boundary geometry, and output attributes include the group fields and corresponding field values.
To generate only one overall boundary geometry for the entire layer, first add the same constant group field value to all features, and then select that field as Group fields in this tool.
Steps
- Start the tool: Open Geoprocessing Toolbox > go to Vector tools > Feature processing > Build > open the Minimum Bounding Geometry tool pane.
- Set the input: Select the Input vector file for which boundary geometry will be calculated.
- Set grouping: To calculate separately by category, administrative area, or project ID, select one or more Group fields. For per-feature calculation, leave this parameter empty.
- Choose a calculation method: Select convex hull, minimum rotated rectangle, minimum enclosing circle, or axis-aligned envelope based on your goal.
- Configure the output: Set the path and name for the Output vector file.
- Run the tool: Click Run. After completion, check whether the output count, group fields, and boundary geometry meet expectations.
Notes
- When input features are collinear or coincident, some methods may return mathematically valid but degenerate geometry types, such as points or lines instead of polygons.
- Minimum rotated rectangle and minimum enclosing circle are planar geometry operations. For longitude and latitude coordinates, project the data to an appropriate projected coordinate system before calculation.
- The current implementation has limited handling for Z values and M values and is mainly intended for 2D boundary geometry generation.
- When group fields are set, null field values participate in grouping. Null values in numeric fields are treated as
0, and null values in text fields are treated as empty strings. - If the input geometry contains self-intersections or empty geometry, run Check Geometry or Repair Geometry first.