Layer intersection refers to the analysis function that performs intersection operations on two or more datasets. For detailed descriptions of the intersect tool, please refer to the Overlay Analysis Tools.
Feature Description
- The source dataset type can be point, line, or region dataset. The overlay dataset type can be line or region dataset. When the source dataset is line type, the overlay dataset supports line type only.
- The result dataset retains overlapping parts of the original two datasets. Point datasets can be obtained through line-line intersection, in which case the output type must be set to point.
Feature Entry
- Spatial Analysis Tab->Vector Analysis->Overlay Analysis->Intersect.
- Toolbox->Vector Analysis->Overlay Analysis->Intersect.
Parameter Description
- Source Data: Select the datasource containing datasets to be intersected. Supports multiple input datasets for intersection analysis.
- Overlay Data: Select the dataset and its datasource to intersect with the source dataset.
- Result Data: Select the datasource to store the result dataset and specify its name.
- Field Settings: Select fields from source and overlay datasets as selected fields for the result dataset.
- Tolerances: Default tolerance values are automatically provided based on input datasets.
After overlay operation, if the distance between two nodes is smaller than this value, they will be merged. The default value is the fuzzy tolerance of the clipped dataset, which can be set in the Fuzzy field under Tolerances in the Vector Dataset Tab of Dataset Properties dialog.
If fuzzy tolerance is not set in Dataset Properties, the default tolerance here relates to the dataset's coordinate system. For details, see Tolerance Description.
- Keep All Source Data Fields: When checked, retains all source data fields. If duplicate field names exist between source and overlay data, fields from source data will be named "FieldName_1" and overlay data fields "FieldName_2".
- Keep All Overlay Data Fields: When checked, retains all overlay data fields. Naming rules for duplicate fields follow the same pattern as above.
- Output Result Type: The default output type matches the source dataset type. When both source and overlay data are lines, the output type must be set to point; otherwise the operation will fail. Example: To obtain bridge locations as intersection points between road lines and river lines, set the output type to point.
Example: As shown in Figure 1 below, field ridges lie at the boundary between two polygons (classification codes 0321 and 0110). To calculate net polygon area by deducting half of linear ridge area along edges: When "Single Object" is checked (Figure 2), the result ridge belongs to one polygon; when unchecked (Figure 3), two line objects are retained. By specifying polygon IDs and deducting corresponding polyline areas, net area can be obtained.
Notes:Before performing overlay analysis, ensure all datasets share the same projection; otherwise the analysis may fail.
Version 11.1 features a redesigned intersect algorithm with significantly improved performance. Differences from previous versions occur when source datasets contain overlapping polygons, leading to variations in result object counts (as shown below).
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