- Define an attribute domain.
- In a geodatabase, a mechanism for enforcing data integrity. Attribute domains define what values are allowed in a field in a feature class or nonspatial attribute table. If the features or nonspatial objects have been grouped into subtypes, different attribute domains can be assigned to each of the subtypes.
- What are the 2 types?
- Coded-value and range
- How are range domains validated?
- Range domains are validated in an editing session through the Editor toolbar.
- What are split and merge policies?
- Split and merge policies define how the values of a field will react once a feature is split or merged (i.e. are the values added, is the highest selected, does the field defer back to the default value). Split policies include default value, duplicate, and geometry ratio. Merge policies include default value, sum value, and weighted average.
- Define a subtype.
- What data type must the field be to apply a subtype to it?
- In geodatabases, a subset of features in a feature class or objects in a table that share the same attributes. For example, the streets in a streets feature class could be categorized into three subtypes: local streets, collector streets, and arterial streets. Creating subtypes can be more efficient than creating many feature classes or tables in a geodatabase. For example, a geodatabase with a dozen feature classes that have subtypes will perform better than a geodatabase with a hundred feature classes. Subtypes also make editing data faster and more accurate because default attribute values and domains can be set up. For example, a local street subtype could be created and defined so that whenever this type of street is added to the feature class, its speed limit attribute is automatically set to 35 miles per hour.
- Objects in an object class and feature in a feature class may be further subdivided into subtypes.
A subtype is a special attribute that lets you assign distinct simple behavior for different classifications of your objects or features. All subtypes of a class share the same set of attributes.
The motivation for defining subtypes of an object class is to introduce a lightweight subdivision of an object class that adds these capabilities: - You can name subtypes to describe each member of a classification of your objects.
- You can define distinct attribute domains for each field in a subtype.
- You can define distinct default values for each field in a subtype.
- You can prescribe the types of relationships that are possible between the objects in a subtype and objects in another subtype in the same or different object class.
- If you write some software code, you can also add custom rules for subtypes of object and feature classes.
An object class does not have to contain subtypes. If none are defined, you can still set attribute domains, default values, and rules - but on the object or feature class as a whole instead of a subtype.
- Subtypes are only permitted on Long Integer fields
- Why do we create subtypes?
- What are the advantages?
- Subtypes increase data integrity and can speed data entry.
- p. 88 in the text
- Describe the spatial adjustment process in ArcMap for transforming data from one coordinate system (or non-real world coordinates) to another coordinate system.
- Georeferencing is used for CAD files and for images. When these are in non-real world they must have real world coordinates to display correctly. A world file is created with the same name as the image or CAD. When these are displayed in ArcMap, the world file is used to provide the coordinates. Georeferencing builds the world file.
Spatial adjustment is a tool used in an editing session for vector feature classes to actually update the data with coordinates. These are three processes that can be used - transformation, rubbersheeting and edgematching. In class we used transformation. This used control points - coordinates that had been collected with a GPS unit. Because this is done in an edit session one can use tools such as snapping to improve the process. - Describe how CAD data is represented in ArcMap. Also see: Contents of CAD drawing.
- Define CAD feature datasets
- CAD feature datasets are an ArcGIS feature data object representation of a CAD drawing. They contain a collection of CAD feature classes that allow you to interact with CAD data in ArcGIS similar to how you would with geodatabases and shapefiles. This includes performing operations such as attribute query, symbol modifications, and conversion. However, CAD feature datasets are read-only, so their feature geometry and attributes cannot be edited.
- Define CAD feature classes
- CAD feature classes are homogeneous collections of CAD features of the same geometry type that possess a common set of attributes. Typical feature classes are geographical representations of features as points, lines, polygons, and multipatches; they can also be map text (annotation). All CAD feature class types will always exist in a CAD feature dataset, even if a feature class does not contain any features. You cannot add CAD feature classes to a CAD feature dataset.
- Define CAD drawing datasets
- CAD drawing datasets are a unique representation of a CAD drawing. They contain all the contents of the CAD drawing. This means that all geometries are organized into a single layer. This design allows you to work with a CAD drawing file as one entry in the catalog or map, similar to how you work with a drawing file in a CAD program.
CAD drawing datasets reside within a CAD feature dataset and are denoted by a white compass icon. They are rendered using the original colors of the CAD entities. They have limited functionality when you compare them to CAD feature classes. You can turn drawing layers on and off, perform coordinate transformations, and modify the display effects (brightness, contrast, and transparency). However, you cannot change their symbols, perform spatial or attribute queries, or use them as a snapping layer. - Understand the differences - which do we use to import to a GIS data format? Which one can we change the symbology of?
- Describe what makes features smart. (chapter 5 in the text)
- How do we progressively add intelligence to features in the Geodatabase?
- What is the importance of the Spatial Reference in ArcGIS? XY domain in the Geodatabase? How is this different than with a Shapefile?
- XY DOMAIN - In Geodatabases, you have to specify the an XY domain for your feature classes. The XY Domain is the 'bounding coordinates' that your features can fall within. If you try to put a point, line, or polygon on the map that is outside these bounding coordinates, it will not let you add the geometry. You can not alter the XY domain after you create it so you must plan for as big as your data may grow geographically.
Shapefiles do not require specifying an XY domain. You can create a shapefile and add a point in Asheville and one in Paris and one in India. The shapefile does not have a bounding box of coordinates the data must fall into. You can put points literally anywhere in the world.
The underlying reason the geodatabase using the XY Domain, and we did not discuss this, has to do with how it stores data and allows the geodatabase to store more precise data because of the XY domain. - What do you know about Raster Catalog's
- A collection of raster datasets defined in a table of any format, in which the records define the individual raster datasets that are included in the catalog. Raster catalogs can be used to display adjacent or overlapping raster datasets without having to mosaic them together into one large file. In ArcView 3.x, raster catalogs were called image catalogs.
Raster catalogs can be constructed from varying imagery types and resolutions. The imagery is referenced rather than mosaicked.
