Feature Description
A single buffer refers to a polygon automatically created around points, lines, or area entities with specified width. The generated buffer results can participate in subsequent analytical operations.
- Currently supports creating buffer zones for point/line/region datasets, but not for CAD datasets, network datasets, or route datasets.
- Parameter settings vary completely depending on data types. For line data, users can choose between round or flat buffer types, while point/area data can only generate round buffers. When using flat type for lines, buffers with unequal left/right radii or single-side buffers can be created.
- When specifying buffer distance numerically: Negative values are allowed for region datasets but prohibited for point/line datasets. Zero buffer distance is invalid for all data types.
- When specifying buffer distance via fields: Objects with empty or zero field values won't generate buffers. Negative values in point/line datasets will be treated as absolute values. For flat line buffers, negative left/right radius field values will use absolute values as right/left radii respectively.
Feature Entry
- Spatial Analysis Tab -> Vector Analysis -> Buffer -> Select Buffer from dropdown menu
- Toolbox -> Vector Analysis tool -> Buffer -> Buffer
Parameter Description
- Data Type: Select data type for buffer creation.
Supports point/region datasets or line datasets. Line buffers require buffer type selection (round/flat), while point/area buffers don't. The following example uses line data to explain parameters.
- Buffer
Datasource: Select datasource containing target dataset.
Dataset: Choose dataset for buffer creation.
The system automatically filters datasets based on selected data type. Only line datasets appear when processing lines, while point/region datasets display accordingly for other types.
Buffer only selected objects: When objects are selected, this checkbox becomes available. Checked: Creates buffers only for selected objects (datasource/dataset become uneditable). Unchecked: Processes all objects in dataset.
- Buffer type settings:
Round: Creates parallel lines on both sides with semicircular ends (default).
Flat: Generates rectangular buffers using adjacent line segments and specified left/right radii.
- Left buffer: Creates buffer on left side of line
- Right buffer: Creates buffer on right side of line
Both left and right buffers are created by default when both options are checked.
- Set buffer unit: Supports millimeters, centimeters, decimeters, meters, kilometers, inches, feet, miles, degrees, yards, etc.
- Specify buffer distance method:
- Left radius: Direct input, numeric field selection, or expression input
- Right radius: Direct input, numeric field selection, or expression input
- Result options:
Union buffer: Merges overlapping buffers into single complex object. Unchecked: Maintains separate buffers.
Keep attributes: Preserves original non-system field attributes (disabled when union buffer is selected).
Show result in map: Automatically adds results to current map window (default enabled).
Arc segment count (4-200): Controls buffer boundary smoothness. Higher values create smoother curves (default: 100).
- Result data settings:
Datasource: Select output datasource
Dataset: Enter output dataset name. Existing names trigger error prompts.
Notes:About buffer radius specification:
- Numeric
- Negative values allowed only for region datasets
- Field
- Only valid for dataset/recordset analysis (non-system fields required)
- Negative values in point/line datasets use absolute values
- For region data: Uses absolute values when union buffer is selected; preserves negatives otherwise
- Field expressions only work with dataset-level analysis (invalid when "selected objects only" is checked)
Related Topics