The Range Fan Calculator Processor can be used to dynamically generate a range fan forward of an event record's point geometry. A range fan is effectively a two-dimensional feature in the shape of a wedge that can be used to represent a visual or contextual range of an event record. The processor uses an anchor point and specified values for the Range, Bearing, and Arc Angle parameters to calculate a range fan polygon.
Examples
The following are example uses of the Range Fan Calculator Processor:
- The Range Fan Calculator Processor can be used to calculate and display the approximate visual range of a moving vehicle. As the vehicle is in transit, the intersection between the vehicle’s range fan (field of view) and an asset on the ground could be used to trigger a notification.
- The processor can be used to display the potential area of impact from an event such as a storm or a plume of smoke from a fire.
Usage notes
Keep the following in mind when working with the Range Fan Calculator Processor:
- The processor typically processes an event record whose geometry provides an anchor point for the range fan.
- The processor can be configured to construct a point geometry from coordinate values retrieved from attribute fields, but the received event record must still have a geometry field the processor can use to store the computed range fan polygon. The geometry field is identified as the field tagged with the GEOMETRY tag. The processor will replace the source event record's geometry with the computed polygonal range fan.
Values must be specified for the Range, Bearing, and Arc Angle parameters to compute a range fan. The bearing is interpreted as an angle greater than 0° and less than 360° measured clockwise from north. The arc angle represents a level of uncertainty on either side of the bearing. The range is a linear value measured in specified units (for example, meters, kilometer, feet, or miles).
- The Range, Bearing, and Arc Angle parameters can be specified as numeric literal values or evaluated as an expression similar to those supported by the Field Mapper Processor. Values entered should resolve to a positive numeric value.
- Use constant values for the Range, Bearing, and Arc Angle parameters when a sensor has a fixed orientation and does not move. For example, a fixed range fan might be computed for a camera with a 160° field of view, facing east, by configuring the processor with the values for the range of 100 (meters), bearing 90° and arc angle 160°.
- Enter field names for the Range, Bearing, and Arc Angle parameters when a sensor's orientation or location changes. For example, as a vehicle's direction of travel changes, so does its bearing. A dynamic range fan can be computed by configuring the processor to retrieve the vehicle's bearing from an event record's attribute to ensure the range fan is always forward-looking and based on the vehicle's direction of travel.
- The Processing Coordinate System WKID parameter is required. This coordinate values determine the linear units of measure and the spatial reference that is used to calculate the range fan's extent. The processing coordinate system must be a projected coordinate system. For more information on projected coordinate systems and their WKIDs, see Projected Coordinate System Tables. When constructing a point geometry from coordinate values to use as the range fan's anchor, the specified processing coordinate system will be used.
- Unlike the Buffer Creator Processor, which will reproject the polygon it produces to match the spatial reference and coordinate system of the input geometry used as the buffer's center point, the Range Fan Calculator Processor is configured with an output coordinate system WKID. The polygonal range fan in event records emitted from the processor will be projected into this output coordinate system.
Parameters
The following are the parameters for the Range Fan Calculator Processor:
| Parameter | Description |
|---|---|
|
Name | A descriptive name for the processor used for reference in GeoEvent Manager. |
|
Processor |
Specifies the processor selected. |
| Source GeoEvent Definition | The name of the inbound event record’s GeoEvent Definition. The processor uses the source GeoEvent Definition to identify fields from the inbound event record to manage fields listed in the drop-down fields for other parameters. |
| Geometry Source | The source of the point geometry used as the range fan's anchor. The processor constructs its range fan forward of this point. The default is Geometry Field.
|
| Geometry Field (Conditional) | The name of the geometry field or the GEOMETRY tagged field from the inbound event record used to identify the point geometry. The processor uses the geometry as the point from which the range fan originates. The point geometry must include a spatial reference. The parameter is shown when Geometry Source is set to Geometry Field and is hidden when set to Coordinate Fields. |
| X Field (Conditional) | The name of the field that contains the x coordinate of the range fan's anchor point. The x and y coordinates are used to construct the point. It must be consistent with the Processing Coordinate System WKID parameter. The parameter is shown when Geometry Source is set to Coordinate Fields and is hidden when set to Geometry Field. |
| Y Field (Conditional) | The name of the field that contains the y coordinate of the range fan's anchor point. The x and y coordinates are used to construct the point. It must be consistent with the Processing Coordinate System WKID parameter. The parameter is shown when Geometry Source is set to Coordinate Fields and is hidden when set to Geometry Field. |
| Range | The linear value used to calculate the range fan's extent. The range is the length, or distance, the range fan will extend forward of the anchor point. The range can be defined using a constant value, the name of an attribute field, or an expression which evaluates to a positive numeric value. A value is required. Note:The units for the Range parameter are defined in the Range Units parameter. |
| Range Units | The unit of measure for the range value. The default is Meters. Available units of measure include the following:
|
| Bearing | The number of degrees greater than 0° and less than 360° measured clockwise from north. The bearing can be specified as a constant value, the name of an attribute field, or an expression which evaluates to a positive numeric value. The bearing bisects the range fan's arc. A value is required. |
| Arc Angle | A number of degrees greater than 0° and less than 360° specifying the range fan's arc. The arc angle can be specified as a constant value, the name of an attribute field, or an expression which evaluates to a positive numeric value. A value is required. |
| Processing Coordinate System WKID | The well-known ID (WKID) of a projected coordinate system consistent with the value specified in the Range parameter. Also used when the X Field and Y Field parameters are specified to construct the range fan's anchor point from coordinate values. An integer value is required. Note:Accurate construction of the range fan polygon requires a processing coordinate system appropriate for the area of interest, location of the range fan's anchor point and extent. For example, if the incoming event records are located in an area consistent with the State Plane projected coordinate system for South Carolina, an appropriate processing coordinate system WKID would be 32133. |
| Output Coordinate System | The well-known ID (WKID) of a coordinate system into which the computed polygonal range fan can be projected. The output coordinate system may be either a projected coordinate system (PCS) or geographic coordinate system (GCS). Note:The output coordinate system can be different than the processing coordinate system. |
Considerations and limitations
There are several considerations to keep in mind when using the Range Fan Calculator Processor:
- A range fan can only be constructed forward of a two-dimensional point. Other geometry types such as multipoint, polyline, polygon, and envelope are not supported.
- The units set in the X Field and Y Field parameters must align with the spatial reference of the projected coordinate system specified in the Processing Coordinate System WKID parameter.
- The Range, Bearing, and Arc Angle parameter values must all evaluate to positive numeric values.
- The Arc Angle parameter value must be greater than 0° and less than 360°. The polygonal range fan may display as a line if an extremely small arc angle is specified (depending on the range, map scale, projection, and feature symbology).