The Envelope Creator Processor can be used to produce a simple rectangular envelope enclosing an event record’s geometry.
Examples
The following are example uses of the Envelope Creator Processor:
- Calculating an envelope around a multipoint cluster of assets can be used to determine a service area for geofencing.
- Calculating an envelope around a concave or irregular polygon can be used to simplify the shape and reduce the number of vertices.
Usage notes
Keep the following in mind when working with the Envelope Creator Processor:
- In contrast to the Convex Hull Creator Processor, which creates a polygon representing the smallest area enclosing a GeoEvent’s geometry, a convex hull is not always rectangular. The Envelope Creator Processor creates a polygon or envelope that is always rectangular.
- Given a point, the processor will create an equivalent point.
- Given a multipoint or line with two or more vertices with varying latitudes, the processor will create an envelope.
- A valid envelope cannot be produced if all a geometry’s vertices share the same latitude.
- The processor requires the field containing the event record’s geometry be specified. A geometry field name can be specified, or the GEOMETRY tag can be applied to a field in a GeoEvent Definition to identify the geometry field.
- The Geometry Field parameter will show the name of every field from every GeoEvent Definition containing a data type of geometry. When selecting the geometry field by name, choose the name of the correct geometry field that corresponds to the event record’s GeoEvent Definition.
- The processor can be configured to either replace the event record's geometry with the created envelope or place the envelope into a new geometry field using the Replace Geometry parameter. Altering an event record's schema by adding a new field requires GeoEvent Server to create a new GeoEvent Definition. The new GeoEvent Definition will be managed by GeoEvent Server and deleted if changes are made to the processor or the GeoEvent Service in which the processor is used.
- Choosing Yes for the Tag the New Geometry Field as Geometry parameter explicitly tells GeoEvent Server which geometry field should be treated as the event record’s realized geometry for subsequent processing or output.
- When sending event records from the processor to a feature service output, ensure only one geometry field exists in the outbound GeoEvent Definition.
Parameters
The following are the parameters for the Envelope Creator Processor:
| Parameter | Description |
|---|---|
|
Name |
A descriptive name for the processor used for reference in GeoEvent Manager. |
|
Processor |
Specifies the processor selected. |
| Geometry Field | The name of the geometry field or the GEOMETRY tagged field from the inbound event record the processor will use to calculate the envelope. |
| Replace Geometry | Specifies whether to replace the current event record geometry with the geometry of the envelope. The default is Yes.
|
| New Geometry Field Name (Conditional) | The name of the new geometry field where the envelope geometry will be stored. The parameter is shown when Replace Geometry is set to No and is hidden when set to Yes. |
| Tag the New Geometry Field as Geometry (Conditional) | Determines whether the new geometry field created by the processor will be tagged as GEOMETRY. The GEOMETRY tag is used by GeoEvent Server to identify the event record’s realized geometry when multiple geometry fields are present. The default is No. This parameter is shown when Replace Geometry is set to No and is hidden when set to Yes. |
| New GeoEvent Definition Name (Conditional) | The name assigned to the new GeoEvent Definition. The new GeoEvent Definition will combine the schema of the inbound event record with the additional new geometry field. The parameter is shown when Replace Geometry is set to No and is hidden when set to Yes. |
Considerations and limitations
Consider replacing the existing event record geometry with the geometry representing the envelope prior to sending the event data to a feature service. Feature services only support one geometry type field, so whichever field has not been tagged as GEOMETRY will be converted and kept as a string.