How to create an interest area GeoJSON: Difference between revisions
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| At the CRS, select an appropriate CRS. | | At the CRS, select an appropriate CRS. | ||
| Click "OK" to complete the export. | | Click "OK" to complete the export. | ||
| A GeoJSON file with a polygon defining the [[ | | A GeoJSON file with a polygon defining the [[Interest area (Area Attribute)|Area of Interest]] has now been created. | ||
}} | }} | ||
| Line 22: | Line 22: | ||
* Multiple discrete features may be present in a single Interest Area GeoJSON. Each feature will be loaded in as a separate [[Area]]. | * Multiple discrete features may be present in a single Interest Area GeoJSON. Each feature will be loaded in as a separate [[Area]]. | ||
** When using MultiPolygons, each feature consisting of multiple Polygons will be loaded in as a single [[Area]] with multiple polygons. | ** When using MultiPolygons, each feature consisting of multiple Polygons will be loaded in as a single [[Area]] with multiple polygons. | ||
* No [[Attribute]]s need to be added to the features. [[Attribute]]s of the features in the GeoJSON file will be ignored when using it during [[Project generation]]. Instead, a single [[INTEREST_AREA]] [[Attribute]] with a value of "1" will be added to each of the [[Area]]s added in this way | * No [[Attribute]]s need to be added to the features. [[Attribute]]s of the features in the GeoJSON file will be ignored when using it during [[Project generation]]. Instead, a single [[Interest area (Area Attribute)|INTEREST_AREA]] [[Attribute]] with a value of "1" will be added to each of the [[Area]]s added in this way. | ||
}} | }} | ||
[[Category:How-to's]] | [[Category:How-to's]] | ||
Latest revision as of 14:14, 5 March 2026
For some calculation models, often those found in Project Templates, the actual area of interest to consider results of does extent across the entire extent of a Project. Instead, only a specific polygon may be relevant. This polygon is known as Interest Area. While creating a new Project, it is also possible to use a file defining such an area to automatically select the appropriate location and extent for the new Project. However, this relies on having a GeoJSON file with such a definition before starting work on a Project.
These steps describe the process in QGIS, but similar steps in other GIS applications can yield the same result.
How to create an interest area GeoJSON:
- Open a new or existing project in QGIS.
- Ensure some background layer exists, so that its possible to know where new features are drawn.
- Move the view to the location where the Interest Area is to be located.
- In the top menu, select Layer → Create Layer → New Temporary Scratch Layer
- Set the Name to "Interest Area", set Geometry Type to Polygon, and click "Ok"
- Use the Add Polygon Feature to draw a polygon in the correct location. Ensure it fits the area of interest as exactly as possible.
- Right-click the layer in the "Layers" list, and select Export → Save Features As
- Set the Format to GeoJSON.
- At the input for the File Name, select the location to save the GeoJSON file to.
- At the CRS, select an appropriate CRS.
- Click "OK" to complete the export.
- A GeoJSON file with a polygon defining the Area of Interest has now been created.
Notes
- Multiple discrete features may be present in a single Interest Area GeoJSON. Each feature will be loaded in as a separate Area.
- When using MultiPolygons, each feature consisting of multiple Polygons will be loaded in as a single Area with multiple polygons.
- No Attributes need to be added to the features. Attributes of the features in the GeoJSON file will be ignored when using it during Project generation. Instead, a single INTEREST_AREA Attribute with a value of "1" will be added to each of the Areas added in this way.