OpenCities 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 OpenCities 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 Imports / Exports dialog (Interoperability dialog in V8i), navigate to the Exports tab. Create a new export and add a Shapefile directory.
Expand the Attached node and notice that there is 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 OpenCities Map is started.
Since the elements are not being read as features, they are not available to OpenCities Map tools such as exporting to shapefiles or the Map Manager.
The First Element Found
When you start OpenCities 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 layer 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 OpenCities 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 OpenCitiesbe 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.
<Feature useCriteria="" name="Public Schools">
<Rule type="Element" score="100" levelName="Schools" elementType="6" />
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
Inferred Level Features (MS_GEOXFM_NO_LEVELFEATURES)
By default, non-cell inferred features are defined using the level name as the feature class name. In addition:
To override this behavior, set MS_GEOXFM_NO_LEVELFEATURES = 1
Inferred Cell Features (MS_GEOXFM_NO_CELLNAMEFEATURES)
For elements inferred as features using cell names, the feature's class name is set to the cell name. In addition:
To override this behavior, set MS_GEOXFM_NO_CELLNAMEFEATURES = 1
Example - DFS Rules for Element Symbology
The following can be used as a simple exercise to illustrate using DFS rules to evaluate an elements colour, weight and style. If they meet the required minimum score of 100, the element will be inferred as a Cable. Note that the elements level is not considered, and the values for the colour, weight, and style are set to 5, 3, and 2 respectively. To create this DFS rule file, simply create a new text file in any folder and add the following text:
<Feature useCriteria="" name="Cable">
<!-- color, weight, style -->
<Rule score="100" type="cexpr">XFMCompareElementSymbology(5, 3, 2)</Rule>
Using the Geospatial Administrator, create a new project and define a workspace.
In the Macro node of the workspace definition, set the variable MS_GEOXFM_DYNAMICFEATURESCORING_FILES=1 to the location of the DFS rule file created above.
Create a simple linear element for a Cable and add a property or two. Set the symbology as noted in the graphic below. Update the Command Manager then save and export the workspace and related metadata.
To test the DFS rule, run the workspace, create a new design file and draw a Cable feature. As expected, the result is a Native Feature:Cable.
As well, create a new level called Highway and draw a line with any colour, weight and style. Since this new element does not meet the minimum score as defined in the DFS rule, it’s identified as an Inferred Feature: Highway, and is added as a Session feature in the Command Manager.
The next step is to verify that the DFS rule is working correctly. To do that, change the symbology of the Highway to match the Cable (CO=5, LC=2 and WT=3). OpenCities now recognizes the element to be a Inferred Feature:Cable which indicates that it met the minimum score of 100 in the DFS rule. As well, the Highway session feature was removed from the Command Manager.
The Data Browser shows both the native and inferred cable features, however the inferred cable does not have property information and it resides on the incorrect level.
To correct this, use Reset Feature from the Features ribbon group (V8i: Geospatial Tools > Utilities toolbox), or issue the following key in: choose all;feature reset all;choose none;null to reset all feature properties to the values defined in the geospatial project.
(Graphic from V8i)
As for the property values, they will inherit the setting as defined in the geospatial project. In this example, the Material property is set to store the last value used in the design file.
For more options on the Reset Feature tool, please refer to OpenCities Map help.
Example - DFS Rules to Evaluate V7 Elements
DFS rules can also be used to evaluate and score elements in a V7 design file. For example, this design file has elements on Level 1 using colours 3, 5 and 7.
In the Macros section of the workspace node, two variables are added:
MS_OPENV7=3 to allow editing of V7 files, and MS_V7_LEVEL_NAME_PREFIX=From_V7_ to define the prefix for unnamed V7 levels.
A DFS rule file can be created to evaluate the symbology and level name of an element. In this example, the rule file has three rules for evaluating the element symbology and one for the level name. In order to qualify as a Cable feature, an element must score a minimum of 100 points where 50 points comes from the symbology section and the remaining 50 comes from the level name. Since the elements are on Level 1 in the originating V7 design file, they will be displayed as From_V7_1 when opened in OpenCities Map. Note that this is new level name is specified in the level rule.
<Feature name="Cable" useCriteria="">
<!-- Colour, Weight, Style -->
<Rule score="50" type="cexpr">XFMCompareElementSymbology(3, 1, 0)</Rule>
<Rule score="50" type="cexpr">XFMCompareElementSymbology(5, 1, 0)</Rule>
<Rule score="50" type="cexpr">XFMCompareElementSymbology(7, 1, 0)</Rule>
<!-- Level Name -->
<Rule score="50" type="cexpr">XFMCompareElementLevelName("From_V7_1")</Rule>
Upon opening, the DFS rules are used to evaluate the elements in the V7 design file and reports them as being Inferred Features:Cable . As with the previous example, these elements can be converted to Native Features by using Reset Feature or this key-in: choose all;feature reset all;choose none;null
DFS Side Effects
When DFS is enabled, it evaluates all elements which includes those of attached references. Depending upon the volume and type of data, this may cause the opening and attaching design files to be slower than expected. This can cause unwanted performance issues that negatively impact your project. Should DFS be causing unwanted performance issues, you may want to consider disabling the DFS engine by defining MS_GEOXFM_NO_DYNAMICSCOREDFEATURES. This variable can be set in the project schema, the UCF, PCF, any CFG file, or even on the shortcut with the –ws switch:
Appendix - DFS Configuration Variables
MS_GEOXFM_DYNAMICFEATURESCORING_FILES - Specifies a list of XML files containing DFS rules for processing. For example:
MS_GEOXFM_DYNAMICFEATURESCORING_FILES > $(MS_GEOXFM_XML_DIR)features/dynamicScoring/*.xml
MS_GEOXFM_NO_DYNAMICSCOREDFEATURES – Defining this variable specifies that the DFS engine is off and will not featurize elements. For example: MS_GEOXFM_NO_DYNAMICSCOREDFEATURES = 1
MS_GEOXFM_NO_LEVELFEATURES - Specifies that the DFS engine should not identify non-cell elements as features with feature name equal to the element's level name if no DFS rule matches the element. The default behavior is that elements are identified as level features if no DFS rule matches the element. Example: MS_GEOXFM_NO_LEVELFEATURES = 1
MS_GEOXFM_NO_CELLNAMEFEATURES - Specifies that the DFS engine should not identify cell elements as features with feature name equal to the element's cell name if no DFS rule matches the element. The default behavior is that cell elements are identified as cell name features if no DFS rule matches the element. Example: MS_GEOXFM_NO_CELLNAMEFEATURES = 1
Appendix - DFS Rule Types
int entityNumber, UInt32 mslink
UInt32 inputColor, UInt32 inputWeight, Int32 inputStyle
UInt16 major, UInt16 minor
UInt16 major, UInt16 minor, UInt32 id
DBLink - Database linkage rule. Current element is checked for a MicroStation database linkage with the specified entity and mslink values.
DBEntity - Database entity linkage rule. Current element is checked for a MicroStation database linkage with the specified entity value.
FeatureDef - Feature definition rule. Current element is compared to the XFM feature definition of the given feature class name using the following comparison types:
true or false - If true, element level name must match a level name specified in feature definition. If the Feature definition contains a list of level names then if element level name matches one of the levels in the list then evaluates to true.
true or false - If true, element cell name must match a cell name specified in feature definition. If the Feature definition contains a list of cell names then if element cell name matches one of the cell names in the list then evaluates to true.
Element - Element rule. Current element is compared to specified element settings using the following comparison types:
name of a level - If specified, element level name must match the specified level name
name of a cell - If specified, element cell name must match the specified cell name
one or more element types - If specified, element type must match one of the specified element types. A zero length linear is identified as element type 0. This identification may be disabled by setting attribute "checkZeroLengthLineElementType" to "false".
element type 3
element type 3 or 4
element type 3, 4 or 12
element types 1 through 12
linear element type with two equal points (zero length line)
Flag denoting if linear element is checked to determine if element is a zero length line. If a zero length line is identified, then the element type identifier is zero. The default value for this attribute is "true".
Appendix - Sample DFS Rules
<Feature useCriteria="" name="tax_proposed">
<Rule type="cexpr" score="100">XFMHasDBLink(2,150)||XFMCompareElementLevelName("tax proposed")</Rule>
<Feature useCriteria="" name="Pole">
<Rule type="DBLink" score="100" entity="2" mslink="130"/>
<Feature useCriteria="" name="Wire">
<Rule type="FeatureDef" score="100" levelName="true" cellName="false">Wire</Rule>
<Feature useCriteria="" name="Cable">
<Rule type="DBLink" score="100" entity="2" mslink="80"/>
<Rule type="Element" score="100" levelName="Cable" cellName="Cable" elementType="2" checkZeroLengthLineElementType="false"/>
The content above is also available in the following PDF.
8468.Dynamic Feature Scoring.pdf