The creation of new project schemas requires initial planning. The following is a suggested workflow that may be helpful to get you started.
"Save early, Save often"
1. Define Geometry Types: Point, Line, or Polygon
Geometry can be one of three geometry types: Points, Lines, or Polygons. Review your data requirements and ensure that each feature can be defined as one of these geometry types. For example:
2. Define Categories to organize the features
While not necessary, categories can help organize the features for ease of use and navigation. An example of a category is Utilities which might contain the following features: Water Mains, Hydrants, Powerlines. And the category BaseMap might contain Rivers, Lakes, Parcels, Parks, Road Centerlines.
3. Define domains
A domain is a list of pre-defined values for feature properties. For example, when placing a parcel, you might have a property called LandUse that can be one of the following: Residential, Commercial, Industrial, Educational, Other. Creating a domain list called LandUseCode would provide these five options as a picklist during feature placement. The contents of a domain list can be defined manually or be queried from a database.
4. Create Feature definitions
Each feature in your project can be defined in the Features node found under All Users which makes them available to every workspace in the project. At this point, the feature definition will contain the name, geometry type, display name, the category it belongs to, an optional description, the zoom min and max settings and a few other settings.
When a feature is created, the Symbology node is made available for setting the appearance of the feature. Defining the feature symbology can be easily deferred until the end of this workflow.
5. Define Feature properties (Optional)
At this point, the foundation of your project has been created. The next step is to define the feature properties - although this is optional, you'll add value to your mapping project by collecting and business data. Feature properties are the containers for your business attributes, for example, a parcel polygon feature might have the following properties: LotID, RollNumber, LegalDescription, Owner, MarketValue, LastSoldDate. A streetlight point feature might have properties such as LightID, KW_Rating, ReplacementCost, StreetID, TypeCode.
In addition to determining each property, its unique details need defining. This includes the property type and its associated settings which are found in the property definition tab.
NOTE: Defining feature properties should be done with thought and care. In some cases it may not be possible to change property details after the property has been created and used in a OpenCities Map project. This is especially true for the data type and database properties.
6. Define Criteria (Optional)
Criteria are used to test property values and take the appropriate action if the criteria evaluates to TRUE. For example, a criteria would be used to satisfy these statements:
7. Define symbology settings (Optional)
It's possible to use your project without defining custom symbology settings. However, if you have CAD standards in place, it would be recommended to incorporate those into your mapping schema. Symbology settings will vary by feature type for example point features contain settings used for cell and text placement, polygon features include settings to define fill, and linear features have just the basic symbology settings.
Criteria can be used to define which symbology settings to apply. This is referred to as Property Based Symbology.
8. Define feature placement metadata
In order to place selected features in a design file, custom placement tools must be created for each feature. This is accomplished by selecting each feature and inserting placement metadata from the right click menu.
Custom placement options are presented that are unique to the feature type.
9. Create Command Manager
The Command Manager contains the list of features exported your mapping schema and is created in the User Interface node.
10. Create User workspace
MicroStation uses a workspace to define the set of files to be referenced during a session. Bentley Geospatial Administrator allows multiple workspaces to be designed. User workspaces are created in much the same way as a geospatial project, with the exception of these unique nodes: Scales, Macros, and Files.
Workspaces are created from the User Workspace node:
Refer to Base Source Directory configuration
Refer to Base Source Directory and Files node
Multiple workspaces can be defined on a single project. This will allow you to structure your mapping project per department or user roles.
Note: If features are created for use with a specific workspace, be sure to update the Command Manager list for the workspace.
11. Export Workspace metadata
Once the project definition is complete, export the project and workspace metadata.
The last step is testing your schema and answering these questions:
Defining a OpenCities Map schema is a time consuming task that will require a working knowledge of MicroStation as well as OpenCities Map. The usability of your schema for tasks such as spatial analysis, querying, thematic resymbolization and so forth, are largely dependent upon a well designed schema. Expect your schema to evolve and mature as you discover new capabilities in OpenCities Map.