SurfaceBuilder
Cuts holes in surface features with other surface features.A surface that is cut by another surface must be co-planar with that second surface, and contain that second surface.
所有表面都反对verted into faces (for example, a mesh is converted into faces – one face per mesh part).
Input Ports
Surface features: it is assumed that any two input surfaces within a group either have a strict containment relationship, or are not overlapping.
Output Ports
Contains the output surfaces.
All but one geometrically identical surface will be output through theUnusedport.Two surfaces are considered geometrically identical if their geometries match exactly.
Non-geometry properties like coordinate systems, measures, traits, and geometry names are not considered when matching input geometries.
Parameters
Transformer
Leaving this parameter blank causes the entire set of input surfaces to form a single group.Alternatively, this parameter allows you to select attributes on which to form groups of surface features – each set of features that have the same value for all of these attributes will be processed independently in a group.
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.
There are two typical reasons for usingProcess 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.
第二个可能的原因是潜在的沟纹e gains.
Performance gains are most likely when the data is already sorted (or read using aSQL ORDER BYstatement) 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 aGroup Byvalue need to arrive before any features (of any feature type or dataset) belonging to the next group.In this case, usingGroup BywithProcess 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.
Parameters
This parameter indicates whether or not surface features used to cut other surfaces should be dropped or output.
This parameter will be added to each output feature and will contain "yes" if that feature was used to cut a hole inside some other feature, and "no" if that feature did not cut into any other features.
If a hole list name is specified, the attributes of the features that were used to cut holes in this surface are added to this attribute list.
Note:List attributesare not accessible from the output schema in Workbench unless they are first processed using a transformer that operates on them, such asListExploderorListConcatenator.Alternatively,AttributeExposercan be used.
If set toYes, theNormal Tolerance in DegreesandOffset Toleranceparameters are enabled.If set toNo, the two parameters are disabled.
Faces must be parallel before they are allowed to cut into each other.If two faces are nearly parallel with normals that are slightly apart, use this parameter to set a tolerance in degrees.The larger the value, the less parallel the faces would have to be while still considered parallel to each other.
Usage Tip: Use this parameter together withOffset Tolerance.
Faces must be co-planar before they are allowed to cut into each other.If two faces are nearly co-planar, but are a small offset from each other, use this parameter to set a tolerance in ground units.The larger the value, the farther away the faces could be while still considered co-planar.
Usage Tip: Use this parameter together withNormal Tolerance in Degrees.
Example
The example below illustrates the input features on the left and the output features on the right.The input consists of surface features that are coplanar.The output consists of features with cut holes wherever the surface features were contained within or intersected other surface features.
Editing Transformer Parameters
Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace.More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers.To access a menu of these options, clickbeside the applicable parameter.For more information, seeTransformer Parameter Menu Options.
Transformer Categories
FME Licensing Level
FME Base edition and above
FME Community
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