The Buffer Creator Processor is used to dynamically create a buffer around an event record’s geometry.
Examples
The following are example uses of the Buffer Creator Processor:
- Generate a buffer around aircraft in-flight to ensure proper distances are maintained in respect to critical sites or other no-fly zones on the ground.
- A buffer placed around a facility can be used as a geofence for alerting when vehicles or personnel are near the facility.
- Create buffers around vessels to ensure safe distances are maintained in narrow transit corridors. Touching or intersecting buffers can be used to indicate that two vessels are too close to one another.
Usage notes
Keep the following in mind when working with the Buffer Creator Processor:
- The Buffer Size parameter is specified as a numeric literal or an expression similar to those supported by the Field Mapper Processor. Values entered for this parameter should resolve to a positive numeric value.
- An attribute field's name can be specified rather than a numeric literal value for the Buffer Size parameter to enable the creation of dynamic buffers based on values from event record data.
- 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 computed buffer or place the computed buffer 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.
- The Buffer Size Units parameter shows a variety of available linear units. Additional units of measure can be displayed and used by modifying the Allowed units list in the global settings in GeoEvent Manager.
- You can specify whether to create a geodesic buffer or use a specified projected coordinate system (PCS) when computing the buffer using the Create Geodesic Buffer parameter. Regardless of the option selected, the buffer in event records emitted from the processor will be reprojected to match the spatial reference and coordinate system of the geometry used as the buffer's center point.
- For example, if an event record routed to a Buffer Creator Processor has a point geometry whose coordinates are expressed as latitude and longitude (consistent with the geographic coordinate system whose WKID is 4326), but the point is located in an area consistent with the State Plane projected coordinate system for South Carolina, you may choose to either compute a geodesic buffer or specify the state plane projection be used by entering the value 32133 in the Processing Coordinate System WKID parameter. In either case, the buffer computed by the processor is projected back to match the geographic coordinate system of the point geometry originally received by the processor.
Parameters
The following are the parameters for the Buffer 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 buffer. |
| Replace Geometry | Specifies whether to replace the current event record geometry with the geometry of the buffer polygon. The default is Yes.
|
| New Geometry Field Name (Conditional) | The name of the new geometry field where the buffer polygon 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. The 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. |
| Buffer Size Units | The unit of measure used to calculate the buffer. Available linear units include, but are not limited to, the following:
Note:Additional units of measure can be displayed and used by modifying the Allowed units list in the global settings in GeoEvent Manager. |
| Buffer Size | The size of the buffer created by the processor. The buffer size can be specified using either a numerical value or using a field name string from the inbound event record's GeoEvent Definition. |
Create Geodesic Buffer | Specifies whether to create a geodesic buffer or use a projected coordinate system (PCS) to compute the buffer. The default is No.
|
| Processing Coordinate System WKID (Conditional) | The well-known ID (WKID) of a projected coordinate system (PCS) the processor should use when computing the buffer. Note that the buffer in the event record emitted from the processor will be reprojected to match the spatial reference and coordinate system of the geometry used as the buffer's center point. For more information on projected coordinate systems and their WKIDs, see Projected Coordinate System Tables. The parameter is shown when Create Geodesic Buffer is set to No and is hidden when set to Yes. |
Considerations and limitations
There are several considerations to keep in mind when using the Buffer Creator Processor:
- GeoEvent Server does not support buffers measured in angular units (for example, decimal degrees).
- Consider replacing the existing event record geometry with the buffer geometry 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 with the GEOMETRY tag will be converted and kept as a string.