Constraint Analysis filters an Area of Interest using one or more constraints defined against other datasets. For example, given a Buildings dataset as your Area of Interest, you can keep only the buildings that are within 200 metres of Parks and outside of Flood zones. The result is a new vector layer with only the features that satisfy every constraint.
Open the tool
Open the right-hand panel in your project, switch to the Tools tab, and select Constraint Analysis.
Inputs
- Area of interest — the main vector dataset (polygons) you want to filter. The currently active dataset is selected by default.
- Constraint dataset — a second dataset to evaluate against. Add as many constraints as you need.
- Option — how the constraint applies:
Within— keep features within the buffer distance of the constraint.Outside of— keep features outside the buffer distance of the constraint.Intersect— keep features that intersect the constraint (no buffer).
- Buffer — distance in your workspace's default unit. Disabled when the option is
Intersect.
Click Add to commit each constraint to the list. Constraints already added appear in a table above with their dataset, option, and buffer; remove individual rows with the trash-can button.
Run
Click Run when you have at least one Area of Interest and one constraint. The result is saved as a new vector layer in your project.
Reading the result
The output dataset contains only features from your Area of Interest that pass every constraint. Features missing from the result failed at least one of the configured rules.
Limits and notes
- The Area of Interest must contain polygons.
- Constraints are combined with AND — a feature must satisfy all of them to pass.
- If your input datasets have filters applied in the Data Filter, those filters are respected when the analysis runs.