Understanding Domains in GIS
In GIS, a domain is a set of rules that defines the valid values for a field in an attribute table. Domains help ensure data integrity, consistency, and accuracy by limiting what can be entered into a field. They are particularly useful in large datasets and collaborative environments where standardization is critical.
Why Use Domains in GIS?
• Data consistency: Prevents typos or inconsistent entries (e.g., "Road" vs. "road").
• Ease of use: Provides drop-down menus for users to select from predefined values.
• Error reduction: Minimizes human error in data entry.
• Enforced standards: Promotes standardized terminology and classification.
Types of Domains in ArcGIS Pro
ArcGIS Pro supports two main types of domains:
- Coded Value Domains
- Used when a field should contain one of a set of specific values.
- Each code has an associated description.
Example:
- Code:
1, Description:Paved - Code:
2, Description:Gravel - Code:
3, Description:Dirt - Range Domains
- Used when a field must fall within a defined numeric range.
Example: Elevation must be between 0 and 3000 meters.
How to Use Domains in ArcGIS Pro
- Create a geodatabase (File Geodatabase required).
- Define domains at the geodatabase level (Catalog pane → Domains).
- Assign the domain to a specific field in a feature class or table.
- Use in editing: When editing data in the attribute table or a map, domain values appear as drop-down menus.
Best Practices
- Name domains clearly (e.g.,
RoadSurfaceType,TreeHeightRange). - Document codes and descriptions for user clarity.
- Reuse domains across multiple feature classes when appropriate.
- Keep domains updated as classification systems evolve.
We hope that this article has been helpful! If you have any feedback or questions, please feel free to send us an email or connect with us for a chat. The NTGISC team is here to assist you further!