Exercise 1: Learning the fundamentals of representations
This topic applies to ArcEditor and ArcInfo only.
In this exercise, you will examine a map that needs to be updated with new symbology. You will use feature class representations to improve the map. Feature class representations give you greater flexibility and control of your map symbology by storing complex, rule-based symbols in the geodatabase along with the map data. You will learn different ways to create a feature class representation within a geodatabase and how to convert symbolized layers into feature class representations.
Creating and modifying feature class representations require an ArcEditor or ArcInfo license. You will need at least an ArcEditor license to complete the steps of this tutorial.
You must copy the tutorial data to a local directory to which you have write access. These exercises modify the databases provided to you, so you should make backup copies of them before you begin so you or someone else can follow the tutorial in the future.
Creating feature class representations in ArcMap
You will work with a topographic map of Austin, Texas. This map contains layers that are already symbolized for you. You will use representations to update and improve some of the symbology.
- Start ArcMap.
- Open Exercise_1.mxd from C:\ArcGIS\ArcTutor\Representation\Exercise_1.
Right-click the RoadL layer in the table of contents and click Convert Symbology to Representation.
The Convert Symbology to Representation dialog box opens.
Examine all the default settings and click Convert.
- The representation Name is automatically populated with the name of the feature class appended by the suffix _Rep.
- RuleID Field is the name of the field that will store an integer value for a feature that references a particular representation rule that dictates how it will be symbolized. The default name for this field is RuleID.
- Override Field is the field that stores any overrides to a representation rule for a feature. It is a BLOB field type. The default name for this field is Override.
- The Behavior When Representation Geometry Is Edited property tells ArcGIS where to store geometry edits made with the representation editing tools. These changes can be stored in either the Override field or the Shape field of the feature class.
- The new layer, RoadL_Rep, is added to the table of contents. The original RoadL layer (symbolized with unique values) is still in the table of contents below the RoadL_Rep layer.
- Hold down the CTRL key and click any check box in the table of contents to turn all layers off. Check the RoadL and RoadL_Rep layers. Toggle these two layers on and off using the check boxes to visually compare how they are symbolized. You may want to zoom and pan in the map to see the differences and similarities.
- Hold down the CTRL key and click an empty check box in the table of contents to turn all the layers on again.
Repeat steps 3 and 4 for the following layers:
When you have finished comparing the new layer to the original layers, hold down the CTRL key and click the six original layers in the table of contents to select them. Right-click one of the selected layers and click Remove to delete these layers from the map.
Only the layers symbolized by representations (with _Rep suffixes) will remain.
Symbolizing layers with representations in ArcMap
- Click the Add Data button and navigate to the BuildingP feature class (inside Representations_1.gdb, TopographicMap feature dataset). Click Add on the Add Data dialog box to add the feature class to the table of contents.
Right-click BuildingP and click Properties.
The Layer Properties dialog box opens.
- Click the Symbology tab.
Click Representations in the Show list on the dialog box. You will see a list of the available feature class representations for BuildingP_Rep.
There is one representation rule for BuildingP_Rep, and it is shown with its properties.
Click OK to close the Layer Properties dialog box.
The buildings on the map are symbolized with the black square defined in the Point Buildings representation rule in the BuildingP_Rep representation.
- Click the BuildingP feature layer in the table of contents to select it. Click it again to highlight the name. Rename it by typing BuildingP_Rep to indicate to yourself that it is symbolized with representations.
- Right-click the BuildingP_Rep feature layer and click Open Attribute Table.
Scroll right, if necessary, to see the Angle field.
The Angle field contains values that define the angles of the buildings as they appear on the ground, relative to either geographic or arithmetic orientation. Although buildings are typically captured and modeled as simple point locations for topographic maps at this scale (1:24,000), it is cartographically desirable to portray them at their true orientation. You will use the values in this field to orient building symbols later in Exercise 2 of this tutorial.
- Close the attribute table of the BuildingP_Rep layer.
- Save the current map as Exercise_one.mxd and close ArcMap.
Preparing a feature class for a new representation in ArcCatalog
When working in ArcCatalog, you may want to create new representations for a feature class using existing symbology that you are familiar with. In ArcMap, the Layer Properties dialog box provides this information, whereas in ArcCatalog, the information about symbology is derived from a layer file. You can create layer files for your feature classes with symbology of your choosing for those times when you choose to create representations in ArcCatalog. In ArcCatalog, you can accomplish this through ModelBuilder, at the Python window, with a script with the ArcPy commands, with the Add Representation geoprocessing tool , or through the Feature Class Properties dialog box. You can also work with a feature class and its properties from the Catalog window in ArcMap.
Create a feature class representation in ArcCatalog
- Start ArcCatalog.
- Right-click the feature class RoadP (inside the TopographicMap feature dataset, in Representations_1.gdb) in the Catalog tree and choose Properties.
Click the Representations tab on the Feature Class Properties dialog box.
The list is empty because the RoadP feature class does not have any feature class representations. You will add one now.
The New Representation dialog box opens. Note the similarities between this dialog box and the Convert Symbology to Representation dialog box in ArcMap you used earlier in this exercise.
- Keep the default name RoadP_Rep and the default field names RuleID and Override.
Check the box to import representation rules from a layer file. Navigate to the RoadP layer.lyr in the Exercise_1 folder.
You can import rules from any layer file. Checking this box allows you to choose where your representation rules come from.
Check the box to assign rules to the features that match the layer file.
This option is only available when the layer file you are importing rules from has the same source as the current feature class. Checking this option will assign representation rules to individual features.
Your dialog box should look like the one below.
The new RoadP_Rep feature class representation appears on the Representations tab of the Feature Class Properties dialog box.
Examining feature class representation properties in ArcCatalog
With the Feature Class Properties dialog box still open, click RoadP_Rep and click Properties.
The Feature Class Representation Properties dialog box opens.
Click the General tab if necessary.
The General tab shows the name of the feature class representation and the two field names, as well as the geometry editing behavior setting. This setting and the name of the feature class representation can be changed from this pane, but for this exercise, leave them as is.
You can use the Help button at the top of the dialog box to click any item on this menu to learn more about the components of feature class representations.
Click the Representation tab.
You will notice that the symbol size is now 2.72 points instead of 4 points as before the conversion. Before conversion, the symbol was a character marker symbol. These symbols are stored as glyphs in a font. The envelope of the glyph is 4 points in size, whereas the symbol inside the envelope is actually 2.72 points. The symbol has converted correctly into a representation, even if the numbers seem unexpected. When you are in ArcMap, you can switch back and forth from the Representation renderer to the Features renderer to see that the new and old symbols are the same size.
This tab lists the representation rules that are part of the RoadP_Rep feature class representation, which currently has only one representation rule, Rule_1.
- Click the name of the representation rule, Rule_1. Once the text is selected, type Road Caps to rename the representation rule.
- Click OK to close the Feature Class Representation Properties dialog box.
- Click OK to close the Feature Class Properties dialog box.
With the RoadP feature class still selected in the Catalog tree, click the Preview tab and choose Table from the pull-down menu.
Examine the attribute table to see the two new columns that have been added: RuleID and Override. The RuleID field stores the numeric values associated with representation rules, in this case, representation rule 1. The Override field will store any feature-level exceptions you make to the representation rules during editing.
- Exit ArcCatalog.
Congratulations, you’ve completed exercise 1.
Things created and accomplished in this exercise:
- Created a feature class representation in ArcCatalog
- Added a new representation
- Symbolized a layer with a representation in ArcMap
- Renamed a representation in symbology
- Converted symbology to representation in ArcMap