AreaGeneralizer
From Fmepedia
AreaGeneralizer is a Workbench Transformer.
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Deprecated Function (http://en.wikipedia.org/wiki/Deprecated) This feature or function is one which is considered obsolete in the latest FME, and whose use is discouraged. |
This transformer has been replaced by the Generalizer
The AreaGeneralizer reduces the density of an area features boundary points by removing points. A tolerance setting defines the situation in which a point can legitimately be removed.
The following algorithms are available:
- Douglas removes vertices which cause a deviation of less than the tolerance the surrounding line segment, but the location of the remaining vertices is not altered.
- Thin removes vertices that are less than the tolerance distance away from an adjacent vertex within a feature. The begin and end points are never moved, unless the entire length of the feature being thinned is less than the tolerance, in which case the feature is replaced by a point feature holding the final coordinate.
This transformer works on an entire coverage of area features which must not overlap. If the area features overlap, then either the LineGeneralizer transformer should be used, or the AreaOnAreaOverlayer should be employed to first create a coverage before entering this factory. In some situations, the Snapper in VERTEX mode may also be used either before, after, or instead of, the AreaGeneralizer. This transformer computes the arc/node topology for the coverage, generalizes the individual arcs, and then recreates the area features. Consequently, it will take much longer than the LineGeneralizer, which operates on individual features in isolation.
Note that this transformer will not do generalization by aggregating (i.e. group several small areas that are close to eachother together into one large area).
3D data seems to be a problem in some cases, it's recommended to only use the AreaGeneralizer with 2D data.
AreaGeneralizer + Coordinate Systems
All features emerge from an AreaGeneralizer with the same coordinate system attached to them - it's a valid feature of the transformer but it does mean that you can't route multiple datasets into the same AreaGeneralizer if they have different coordinate systems. If you do this at least one dataset will be wrongly tagged and will be incorrectly reprojected in the output.
Q) I used to use AreaGeneralizer in FME Desktop - but now it is no longer there. Why is this?
A) The AreaGeneralizer makes use of the TopologyFactory which is not part of FME Desktop. In the older FMEs there was only a "generalizer" transformer. Now, there is a LineGeneralizer and an AreaGeneralizer. The AreaGeneralizer is the one that uses topologyfactory and as such is not available in the FME Desktop.
The LineGeneralizer IS EXACTLY THE SAME as the old Generalizer, and can process area features in the same way; all that happens is that slivers/etc can enter into the data. But that is exactly what the old Generalizer did anyway. Note that the @Generalize function is still in desktop.
