OpenCities Map supports viewing features based on a view scale. This is achieved by setting the feature symbology in the Map Manager or as part of the features definition in the Geospatial Administrator.
Using the Map Manager has a number of benefits including the following:
- Each feature can have up to four scale ranges defined consisting of the default scale and three user defined scales.
- The source of the feature is irrelevant; they can be queried from a spatial database or be DGN resident.
- Scale ranges are defined and stored in the DGN.
- Scale ranges are easily modified when needed.
In the image below, the tree symbols are visible at all view scales:
To specify the a scale range in the Map Manager, select Symbology from the features right click menu.
In the feature Symbology dialog, set the Thematic Definition to one of the three User Defined options.
In the Thematic Classes pane, expand Class Properties and turn off the From Feature Definition option. Then proceed to set the minimum and maximum scales as needed.
The result is immediate.
In the image below, View 1 is 1:350 and shows the trees while View 2 is 1:450 and does not.
If you prefer, you can define the default visible scale ranges as part of the feature class definition. To do that, set the Zoom Min and Max options in the Feature Definition tab in the Geospatial Administrator. This will take effect for new feature queries or for newly placed features.
- Key-in to set view scale