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Dynamic Feature Scoring
Bentley Map has the ability to open and display the contents of a MicroStation design file. However, to use the export tools in the Map Interoperability dialog, the Map Manager, the Data Browser, or publish the elements for Bentley Map Mobile, the elements need to be seen as XFM features.
To do that, you have two choices:
Tip: DFS is a display-only function and does not make changes to the actual file. For this reason, it also works on read-only files.
Tip: When DFS is applied to elements in a design file, you retain the ability to use the Map Manager and its functionality. This includes symbology overrides and thematic resymbolization.
Enabling or Disabling DFS
DFS is enabled by default is applied to all new elements and when references are attached. It results in the word Inferred Feature when you hover your mouse over a non-feature element. This allows the plain non-feature elements to be available for use with Bentley Map tools as described above.
In addition to the Inferred Feature note, you can also perform the following test to verify the presence of DFS.
From the Map Interoperability dialog, navigate to the Exports tab. Create a new export and add a Shapefile directory.
Expand the Attached node and notice one feature class per inferred feature in the design file.
Likewise, the inferred features are available for use with the Map Manager.
Defining MS_GEOXFM_NO_DYNAMICSCOREDFEATURES will turn off the DFS engine which results in the elements being identified the same as in MicroStation.
Since this variable only needs to be defined, you can set it either of the following:
MS_GEOXFM_NO_DYNAMICSCOREDFEATURES = 0
MS_GEOXFM_NO_DYNAMICSCOREDFEATURES = 1
Hint: For testing and learning purposes, set this as a temporary variable with this key in: EXPAND SET MS_GEOXFM_NO_DYNAMICSCOREDFEATURES = 1 . It will require you to re-open the design file, but is disabled when a new session of Bentley Map is started.
Since the elements are not being read as features, they are not available to Bentley Map tools such as Exporting to shapefiles or the Map Manager.
The First Element Found
When you start Bentley Map, and if there are no native features found, it will look at the first element on each level and set the class type to match. In other words, if there is a line and a polygon on the Schools level, only the line is found and the feature class is set to line.
Let’s take a closer look.
At first glance, the Schools level appears to contain polygons to represent individual school grounds.
However, creating a Shapefile directory shows that the School level is being read as a linear feature class when it should be a polygon.
When this is encountered, it’s up to you to resolve the issue which may require a detailed analysis of each level. This is especially true when CAD standards have not been followed and levels contain a blend of element types.
In this example, the School level appears to have shapes, lines and arcs. Before proceeding, the lines and arcs should be evaluated and cleaned-up as necessary.
Once cleaned, a new export shows the School level being treated as a polygon feature class which is correct for this particular design file.
Behind the Scenes
DFS uses scoring rules to dynamically evaluate the elements at run time. For those familiar with MicroStation GeoGraphics, DFS is similar to the Attach Best Feature command in which various element criteria was evaluated in order to meet or exceed a minimum score before feature tagging selected elements.
A similar element evaluation and scoring system used with DFS with the most notable differences being that all evaluations are made at runtime as opposed to a batch method, and no persisted feature tags are required.
DFS Rules Configuration
During Bentley Map file open and load events, all non-XFM feature elementsare evaluated against the set of DFS rules. DFS rules can be manually defined by you, by other processes such as Bentley Geospatial Administrator and DGN2SDO, or be generated on-the-fly in order to maximize the amount of data which can be consumed without the need for bulk data conversion.
The DFS engine maintains a feature rules list read from XML files specified in the configuration variable MS_GEOXFM_DYNAMICFEATURESCORING_FILES
Edit this variable to point to a list of XML files containing your DFS rules. This variable can be added to the Macros node of your project schema, or to the User Configuration File (.ucf) from the Workspace Configuration settings.
Feature Rule Scoring
A feature rule is considered a match to an element when the combined score for the feature's rule(s) is greater than or equal to the minScore defined in the DFS rules file.
The feature's rules are evaluated and scored if evaluated to true until either the total score reaches minScore or no more feature rules exist.
The following is an example of a very simple rule defined in an XML text file. It specifies that if a shape element (Type 6 ) is found on a level named Schools, it will be given a feature class name Public Schools.
<FeatureScoringRules minScore="100">
<Feature useCriteria="" name="Public Schools">
<Rule type="Element" score="100" levelName="Schools" elementType="6" />
</Feature>
</FeatureScoringRules>
If no rule matches the element, the default behavior is to identify the element as a named feature based upon the level or cell name. This behavior can be overwritten by the following variables:
MS_GEOXFM_NO_LEVELFEATURES = 1
MS_GEOXFM_NO_CELLNAMEFEATURES = 1
The content above is also available in the following PDF.
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