SectorGenerator

This transformer only accepts points as input. All other geometries are rejected.

2D points are completely supported, but 3D points may result in incorrect Azimuth lines. If you have points with z values, try removing the z values by using the 2DForcer transformer first.

Resulting sectors are output via this port. The sectors are output as rich geometry polygons with arcs or ellipses.

These are lines showing the direction each input point is facing (or influencing). Each line starts from an input point, has a length equal to its input radius, and goes to the direction of its input azimuth.

For each site, a point is created with coordinates that are the average of the coordinates of all points accepted for that sector. This point is the center of all sectors generated for a site.

If a Sector Name Attribute is specified and there are points with the same sector and site names, only the first point meeting all requirements is considered for creating sectors and the rest are output via this port.

Upon entering transformer, if a point is found to be farther from any of the other points in its site than the specified Maximum Distance Between Site Points, it will be dropped from sector generation and output from this port.

These are output points that are missing or have invalid values for required attributes.

Invalid features are left untouched and output via this port. Invalid features are non-point features and point features with missing or invalid values for required attributes.

This option allows you to select attributes that define which groups to form. Each set of features that have the same value for all of these attributes will be processed as an independent group.

Note: The Group By parameter cannot be used if the Input is Ordered by Site Name parameter is set to Yes.

Process At End (Blocking): This is the default behavior. Processing will only occur in this transformer once all input is present.

Process When Group Changes (Advanced): This transformer will process input groups in order. Changes of the value of the Group By parameter on the input stream will trigger processing on the currently accumulating group. This may improve overall speed (particularly with multiple, equally-sized groups), but could cause undesired behavior if input groups are not truly ordered.

Considerations for Using Group By

There are two typical reasons for using Process When Group Changes (Advanced) . The first is incoming data that is intended to be processed in groups (and is already so ordered). In this case, the structure dictates Group By usage - not performance considerations.

The second possible reason is potential performance gains.

Performance gains are most likely when the data is already sorted (or read using a SQL ORDER BY statement) since less work is required of FME. If the data needs ordering, it can be sorted in the workspace (though the added processing overhead may negate any gains).

Sorting becomes more difficult according to the number of data streams. Multiple streams of data could be almost impossible to sort into the correct order, since all features matching a Group By value need to arrive before any features (of any feature type or dataset) belonging to the next group. In this case, using Group By with Process At End (Blocking) may be the equivalent and simpler approach.

Note: Multiple feature types and features from multiple datasets will not generally naturally occur in the correct order.

As with many scenarios, testing different approaches in your workspace with your data is the only definitive way to identify performance gains.

This is the attribute that determines the site to which an input point belongs.

The direction each input point faces (or influences). The Azimuth Attribute value is measured in degrees clockwise from North.

For an Azimuth Attribute value to be valid, it should be nonnegative and less than 360.

If a Sector Name Attribute is specified, then each feature entering the SectorGenerator will be checked to see if its sector name is already in use within its site. If it is, then it will be output on the ExtraPoints port.

Radius of influence for each sector. This determines radius of each sector in a site. It is also the length of each input point’s Azimuth Line.

The maximum distance a point can have from any of the other points in its site and still be considered in sector creation. Points are considered in the order they enter the transformer, with each new point tested against all other points already accepted as a part of its site.

If a nonconstant value is specified for this parameter (for example, an attribute value, which may differ from feature to feature), then when comparing the distance between two features, the maximum distance will be calculated from the feature that entered the transformer earlier.

If this option is set to Yes, the SectorGenerator assumes that each site’s input features occur consecutively in its input. Processing will occur on each site as it is input, instead of waiting for all features before starting. Setting this parameter to Yes can conserve the use of resources.

Note: Note that setting this parameter to Yes will cause the translation to fail if any Group By attributes are specified.