multiple ring buffer
Instructions for use
Multiple ring buffer refers to creating multiple buffers within specified distances around a geometry. The generated buffer results can continue to participate in subsequent analysis operations.
- Currently, the application does not support creating multi-buffers for CAD datasets and network datasets.
- For line data, when creating a multi-buffer, you can choose between round or flat buffer types; for point/polygon data, the system defaults to generating only round.
Function Entry
- On the Spatial Analysis tab -> Vector Analysis -> Buffer -> dropdown menu, select the "multiple ring buffer" item;
- Toolbox -> Vector Analysis tool -> Buffer -> "multiple ring buffer" item;
Parameter Description
- Buffer
Data source: Select the data source where the dataset to create a multi-buffer is located.
Dataset: The system supports creating multi-buffers for point, line, and polygon data, so the "Dataset" dropdown list displays all point, line, and region datasets in the selected data source. Here, select a dataset that requires creating a multi-buffer.
- Buffer Type
If creating a buffer zone for line objects, the parameters in the buffer type area are available, allowing you to set the type of multi-buffer for line objects.
- Round: When creating a multi-buffer, draw parallel lines on both sides of the line according to the buffer distance, and draw semicircles at the endpoints with the buffer distance as the radius to connect the buffer zone. The default buffer type is round.
- Flat: When creating a multi-buffer, use the segment between adjacent nodes of the line object as one side of a rectangle and the left radius or right radius as the other side to generate a rectangular-shaped buffer zone. For line data, when generating flat, it can create multiple ring buffers in a single direction.
- Left radius: Create a multi-buffer based on the buffer radius in the left area of the line data.
- Right radius: Create a multi-buffer based on the buffer radius in the right area of the line data.
- Buffer Radio List
Use the toolbar buttons such as batch add, insert, and delete to set the buffer radius. In the buffer radius list, the buffer radii arranged from top to bottom correspond to the multiple ring buffers. Click the value in the "Radius" column to modify the buffer radius.
- Batch add: Click the "Batch Add" button in the toolbar to open the "Batch add" dialog box, where you can set buffer radius values with a certain incremental/decremental rule. Each level of buffer radius creates a buffer zone based on the buffer object. The system defaults to creating buffers from 10 to 30 meters with a 10-meter interval. The added buffer radius values will be displayed sequentially in the buffer radio list.
- Start value: Set the radius value of the innermost buffer.
- End value: Set the radius value of the outermost buffer.
- Step: Set the interval distance between buffer levels, i.e., the buffer radius difference.
- Segments: Set the number of levels for creating a multi-buffer.
- Update end value: Check this box to have the system automatically calculate the radius value of the outermost buffer in the generated multiple ring buffer based on the input start value, step, and segment count. If unchecked, the system defaults to using the input end value for the outermost buffer radius.
- Insert: Select one or more buffer radii, click the Insert button to add a buffer radius value before the selected one(s), with a default inserted value of 10.
- Unit: Available buffer radius units include: millimeter, centimeter, decimeter, meter, kilometer, inch, foot, mile, degree, yard, etc.
- Batch add: Click the "Batch Add" button in the toolbar to open the "Batch add" dialog box, where you can set buffer radius values with a certain incremental/decremental rule. Each level of buffer radius creates a buffer zone based on the buffer object. The system defaults to creating buffers from 10 to 30 meters with a 10-meter interval. The added buffer radius values will be displayed sequentially in the buffer radio list.
- Parameters: Set whether to merge the generated multiple ring buffers, retain attributes, and the number of semi-circular arc segments, etc.
- Union buffer: Check this option to perform a union operation on buffers with the same radius. Uncheck it to retain the generated buffer results without merging. As shown below, multiple ring buffers are created for two sectors (blue). To display the buffer effect more intuitively (Figure 1), create a thematic map based on the buffer radius for the results. When moving the results, buffers with the same radius are merged into a complex object; Figure 2 shows one group of merged buffers. Note: Without checking "Union buffer," buffers with the same radius are not merged and remain as separate simple objects.
Figure 1: Multiple ring buffer results Figure 2: A group of merged buffers - Generate ring-buffer: Check this option to create multi-buffers where the outer buffer is adjacent to the inner data as a ring-shaped area. Unchecking it makes the outer buffer an area that includes the inner data. This is checked by default.
- Retain attributes: Check this option to have each generated buffer retain the non-system attribute fields of the original object. Unchecking it will lose the non-system attribute fields of the original object. This is checked by default. Note: This option is unavailable when "Union buffer" is checked.
- Number of semi-circular arc segments (4-200): Used to set the smoothness of the generated buffer boundary. A larger value means more divisions for arcs/arc segments, resulting in a smoother boundary. The range is 4-200, with a default value of 100.
- Union buffer: Check this option to perform a union operation on buffers with the same radius. Uncheck it to retain the generated buffer results without merging. As shown below, multiple ring buffers are created for two sectors (blue). To display the buffer effect more intuitively (Figure 1), create a thematic map based on the buffer radius for the results. When moving the results, buffers with the same radius are merged into a complex object; Figure 2 shows one group of merged buffers. Note: Without checking "Union buffer," buffers with the same radius are not merged and remain as separate simple objects.
- Result Data:
- Data source: Select the data source to save the generated multiple ring buffer results.
- Dataset: Enter the dataset name to save the generated multiple ring buffer results. If the input dataset name already exists, an invalid dataset name prompt will appear, requiring re-entry.
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