Frequently asked questions about representations
General questions about representations
What is a representation?
A representation is a property of a feature class that stores information about the way its features should be symbolized. Feature classes can support multiple representations to display their features differently on different maps.
How do I draw representations on my map?
A layer can be symbolized using any representation associated with the source feature class.
Are representations made up of symbols?
Not exactly. Representations are a collection of representation rules that generate a display geometry and a symbol to draw that geometry.
What is the difference between a representation rule and a regular symbol?
Unlike regular symbols, representation rules can create dynamic feature geometry that differs from the spatial geometry, can be controlled by special symbol vertices called representation control points, and can support feature-specific overrides to the rules.
Do representations require a different type of layer?
No. There is no change to the type of layer. Representations are just a way to symbolize regular layers that point to feature classes that have representations.
Are representations a data type?
No. A representation is a property of a feature class. Representation information is stored in additional feature class fields and in a geodatabase system table.
How do I manage representation symbology?
Representation symbology is defined within the representation rules. The structure of the rules can be managed as properties of the feature class or through the properties of a layer drawn with the representation. It is important to understand when working from a layer that you are making changes to the source feature class itself, not just changing properties of a layer. These changes will persist in any other map referencing that feature class representation.
Do I need to start with symbolized data to use representations?
No, but it is better if you start with symbolized data.
You can build representation rules from first principles in ArcCatalog or ArcMap. The difference between defining representation rules and defining standard symbols is that representation rules draw features more intelligently, can dynamically alter geometry before drawing, and are attached to a feature class instead of a layer.
Alternatively, you can leverage the advantages of representation on existing maps by converting a symbolized layer directly to a set of representation rules on a source feature class. This is a shortcut to avoid re-creating symbology that you have already defined. If you were making a new map with new symbol specifications, you would not need to follow the workflow of making symbolized layers first.
What happens to my feature class once a representation is added to it?
Two fields are appended to a feature class each time a new representation is added to it. By default, they are named RuleID, which associates a representation rule to each feature, and Override, which holds feature-specific exceptions to the representation rules.
How do I assign representation rules to features?
Representation rules are linked to features through the RuleID field, which is an integer field with a coded-value domain. Each rule in a representation has a unique integer and name. You can apply representation rules to features by simply calculating values in this field, using the Representation Properties window in an editing session, or using the Calculate Representation Rule geoprocessing tool.
Can I use my data to drive representation symbology?
Yes, you can do this through field mapping. Each property of a representation rule, geometric effect, and marker placement style can be mapped to an explicit field in the feature class.
The following field types are used for field mapping:
- Numeric value properties: Float and double
- Drop-down list properties: Short integer and long integer
- Check box properties: Short integer, long integer, and text
- Color swatch properties: BLOB
Is the representation geometry of a feature different from its spatial geometry?
It can be. Representation rules can contain geometric effects that dynamically modify geometry—and can even switch geometry type. It is also possible to edit feature geometry and store the result so it is only accessible by the representation symbology. The spatial geometry is unaffected.
Can feature representations be modified with the standard editing tools?
Yes. The features can be selected and edited using standard editing tools. Changes to the geometry of the features will be stored in either the Shape field or the Override field, depending on the geometry editing behavior setting.
Can features without representations be modified with the representation editing tools?
No. Tools on the Representations toolbar are only accessible to selectable feature layers that are currently drawn with representations.
Using representations in a multiuser environment
How do cartographic representations behave within the different ArcSDE geodatabase editing environments (versioned, nonversioned, save to base)?
Feature class representations behave the same as the feature type they are associated with.
Do representations work in Oracle? DB2? Informix? UNIX?
Yes to all.
Do representations work in replication?
Yes. If your data has representations prior to replica creation, they will be replicated. If you apply a symbol to a feature in one replica and synchronize, the symbol will also be applied to the feature in the relative replica. Modifications to representations, however, are not supported. For example, consider the case where a new symbol is added to a representation and applied to a feature in a replica. When that feature is synchronized, it will be drawn with an unknown symbol in the relative replica since the new symbol doesn't exist there. It is also possible to add a different symbol with the same ID to the relative replica. In this case, the feature added from the synchronization will be drawn with the incorrect symbol in the relative replica.
Do representations work in archiving?
Using representations with other data types
Do representations work in 3D?
- In ArcGlobe, you can use representations for symbology of rasterized features. You cannot use representations for symbology of vectorized features.
- In ArcScene, representations are not supported.
Do representations work in geometric networks?
Do representations work with ArcGIS Publisher and in ArcReader?
Yes. Representations can be published into a .pmf file and can be viewed in ArcReader.
How does ESRI Production Mapping work with representations?
Releases 9.2 and higher Visual Specifications components of ESRI Production Mapping (formerly known as PLTS for ArcGIS) extend representation functionality by adding systematic management of representations across many layers, as well as maintaining a link between feature attribution and representation rules.