Feature attribute table

From wiki.gis.com
Jump to: navigation, search


Definition

Feature attribute tables are special sets of tables created for various feature classes. Feature attribute tables are INFO data files that contain a number of predefined items and additional user-defined attributes for each feature. A number of feature attribute tables can be created for coverage, each associated with a particular feature class. A feature attribute table is named after the coverage with a three-letter code indicating the type of feature attribute table.


Description

The most commonly used address fields are in the attribute tables. The attribute table contains the following default fields:


ObjectID—the ObjectID field is maintained by ArcGIS and guarantees a unique ID for each row in a table. It can be used as an image ID when using the Lock Raster mosaic method.


Raster—Stores the link to the raster dataset and any individual properties, functions, or metadata. You can preview the processed raster by clicking in this field and clicking the arrow button that appears. In the window that appears, you can edit the functions and preview the properties and metadata.


Name—Name of the source defined by the raster type, which can be the name of the raster dataset file or the metadata file defined in the raster type


LowPS and HighPS—These values are extracted from the source rasters and used to define the range of pixel sizes that the raster dataset contains. For example, a raster dataset that contains a pyramid (or internal overview) will have a range of pixel sizes—the low value will represent the base pixel value and the high value will represent the top overview that is being used. For raster datasets with no pyramids, the low and high pixel sizes may be the same value.


Category— Used for quickly identifying the type of dataset and its status within the mosaic dataset:

  • 0—Unknown
  • 1—Primary (base) data
  • 2—Overview
  • 3—Unprocessed overview
  • 4—Partially processed overview
  • 253—Uploaded
  • 254—Incomplete and needs to be synchronized
  • 255—Custom item


Tag—Used for identifying the raster dataset that will participate in functions defined in a function template. For example, importing one mosaic dataset to another using the Table raster type (with some function templates defined on the raster type) heavily depends on Tag. In most cases, the value is defined by the raster type used for creating the dataset entry within the table.


GroupName— A name given to one or more rows in the table that belong together. For example, for a QuickBird scene, the panchromatic and multispectral rasters are added as separate items in the table. Since each is required to participate in pan sharpening when added using a particular raster type, they will be assigned a group name. This is defined by the raster type that created the dataset entry within the table.


ProductName— This is derived from either the name or product type defined in the raster type.


CenterX and CenterY— The x- and y-coordinates identifying the centroid or nadir of the raster dataset. They are used to render a mosaicked image when the mosaic method is Closest to Nadir or Closest To Viewpoint.


ZOrder— Overrides the default ordering used in determining how the rasters will be mosaicked together. If the value is 0, the default ordering defined as part of the mosaic method is used. If the value is set to a number below 0, the raster is always displayed on top with a high priority. This can be used, for example, to display a lower-resolution raster with a specified footprint to cover areas that should not be seen at high resolutions. The lower the value, the higher the display order. If the value is set above 1, the raster dataset is always displayed as a background when no other raster exists covering the requested area. This can be used to provide a background image.


SOrder—Values in this field (not ZOrder) are used for sorting overlapping datasets when using the Seam line mosaic method. This field is populated by the Build Seam lines tool based on the mosaic rule specified in the tool.


Feature attribute tables are special sets of tables created for various feature classes. Feature attribute tables are INFO data files that contain a number of predefined items and additional user-defined attributes for each feature. A number of feature attribute tables can be created for a coverage, each associated with a particular feature class. A feature attribute table is named after the coverage with a three-letter code indicating the type of feature attribute table. For example, a coverage named LOTS that contains polygons will have a polygon attribute table (PAT) named LOTS.pat.

Feature Attribute Table within Coverage

Feature class Feature attribute table naming convention Description
Point <cover>.pat Point attribute table
Arc <cover>.aat Arc attribute table
Node <cover>.nat Node attribute table
Route <cover>.rat<route> Route attribute table
Section <cover>.sec<route> Section attribute table
Polygon <cover>.pat Polygon attribute table
Region <cover>.pat<region> Region attribute table
Annotation <subclass>.tat Text attribute table


The feature attributes tables that can exist within coverage


References

Notes

  • Feature attribute tables have special item formats and standards. A minimum set of items is always found in each feature attribute table. For example, each PAT always contains at least four items: AREA, PERIMETER, COVER#, and COVER-ID.
  • Point attribute tables have the same .pat extension and contain the same items as polygon attribute tables. For this reason, a coverage cannot contain both point and polygon features.
  • There is always one record in the feature attribute table that corresponds to each feature in the coverage. Both the spatial information used to define the coverage feature and the corresponding record in the feature attribute table contains the feature number so that a one-to-one correspondence is maintained between the feature and its attribute record.
  • Users can add items to a feature attribute table and use them as keys to relate other attribute information to features. Thus, the feature attributes table acts as a key table between coverage features and additional attribute information about each feature.
  • Even though the records in a feature attribute table maintain a one-to-one correspondence with coverage features, one-to-many and many-to-many relationships can be managed between the features attribute table and corresponding tables.

See Also

  • Attribute Field