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Adding a VPF table in ArcView

Every VPF theme in ArcView has an associated feature attribute table. To open the theme table, make the desired theme active and click the Open Theme Table button [image].

You can add additional VPF tables so that you can view them in ArcView. You can also use these tables to Join or Link to feature attribute table.

To add a VPF table to your project

1	Make the Project Window active.

2	From the Project menu, choose Add Table

3	From the File Type list, choose the appropriate VPF table type (or choose All files option to list all files).

4	Navigate to the directory that contains the file you want to add.

5	Double-click the file you want to add or choose the file and press OK.

ArcView adds the table to your project.

The following are the standard VPF tables (and tables with standard VPF extensions) that are supported in ArcView:

VPF table names	Description
cat	Coverage Attribute table
cnd	Connected Node Primitive table
dht	Database Header table
dqt	Data Quality table
ebr	Edge Bounding Rectangle table
edg	Edge Primitive table
end	Entity Node Primitive table
fac	Face Primitive table
fbr	Edge Bounding Rectangle table
fca	Feature Class Attribute table
fcs	Feature Class Schema table
grt	Geographic Reference table
lat	Library Attribute table
lht	Library Header table
rng	Ring table
txt	Text Primitive table
Char.vdt	Character Value Description table
int.vdt	Integer Value description table
VPF table extensions
.aft	Area Feature table
.ajt	Area Join table
.cjt	Complex Join table
.doc	Narrative table
.fit	Feature Index table
.lft	Line Feature table
.ljt	Line Join table
.pft	Point Feature table
.pjt	Point Join table
.rat	Related Attribute table
.tft	Text Feature table


Adding a VPF theme to a view

In ArcView, working with VPF coverages (contained in a VPF library) is similar to adding themes from ARC/INFO coverages. Before you use VPF databases in ArcView you must first load the VPF Viewer extension

To add VPF themes to your View

1	Click the Add Theme button [image]. This is the button you use to add spatial data to your map. In the dialog that appears, navigate to the VPF database.

2	Double-click the VPF library containing the spatial data that you want to add to your map. All the VPF coverages under this library will be listed on the left hand side of the dialog. The coverages that contain more than one feature class will be shown with yellow folder icons next to them.

3	Click on the yellow folder icon next to one of these coverages to see what feature classes it contains.

4	Click on the feature class you want to add. To select  several feature classes, hold down SHIFT key and select them.

5	Click OK. The selected feature classes will be added to your view as themes.

If the VPF coverages are tiled and the area of interest is not set prior to adding themes, ArcView chooses the center tile as the default area of interest for your view. You can change the default area of interest of your view using the Area of Interest tool.

Tip   Add the tile reference coverage as a theme to assist you in defining the desired area of interest.

Notes

 You can add themes from multiple VPF libraries. However, a view can only have one area of interest.

 Any action which has been performed on the theme, such as a table join, field index, or theme definition, will be re-executed each time the area of interest is reset.

 ArcView uses the Coverage Attribute Table’s (cat) coverage description field for default coverage names.

 If you are adding data to a 3D Analyst view, see Adding a 2D or 3D VPF Theme to a 3D Analyst view.


VPF Viewer extension

This ArcView extension enables you to work with Vector Product Format (VPF) data in ArcView. VPF coverages can be added to views as themes, symbolize, query, etc.

To load the VPF Viewer extension, make the ArcView Project window active and then choose Extensions from the File menu.

If you don’t see the VPF Viewer extension in the list, its possible that you may not have installed the extension.


What is VPF?

The Vector Product Format (VPF) is a standard format, structure, and organization for large geographic databases that are based on a georelational data model. The VPF databases are the U.S. Department of Defense Military Standard. The Defense Mapping Agency (DMA) supplies VPF databases for digital vector products developed at a variety of scales. VPF has also been adopted into an international spatial standard as the Digital Geographic Information Exchange standard.

VPF data model

The VPF data model has five levels. At the lowest level, a VPF database consists of geometric and cartographic primitives. A primitive is the smallest component of the VPF data structure (primitives that are related to thematic information are called features). Both features and primitives make up coverages, which in turn make up libraries; and finally, a database is made up of libraries. Primitives are the VPF equivalent of ESRI’s ARC/INFO coverage files (for example, arc, pal, and lab).

The VPF data structures are implemented using directories, tables, and indices. Directories are the basic structural component of VPF databases. Each level of a VPF database (for example, library, coverage, tile) is organized into a directory. VPF directories are then arranged hierarchically from the database level. VPF data tables and indices are hierarchically arranged within directories.

The following figure shows the VPF database directory structure:

For detailed VPF specifications, refer to the Department of Defense Interface Standard For Vector Product Format - MIL-STD-2407.

VPF Metadata

The VPF data model is self-defining, which means it contains information about the data that it stores. This information is called metadata and is primarily used in two ways:

 To describe the contents of a table

 To provide information about other tables or files in the database.

The following are some of the standard metadata tables found in VPF databases:

Metadata table/file	Description
Database header table (dht) Library header table (lht)	Database and library header tables describe the contents of the database and the library, respectively, and give administrative information about them. Both of these tables are developed in accordance with the Digital Geographic Information Exchange Standard (DIGEST). The precise content and arrangement of the database is described by the library, coverage, and feature class attribute tables.
Narrative tables (*.doc)	Narrative files are simply tables with fixed-length text records. These files provide a database publisher with an extremely flexible venue for documenting the contents of tables and columns. In addition to documenting data columns, narrative files also document VPF tables.
Value description tables (*.vdt)	Value description tables store additional pieces of metadata associated with feature tables. For example, descriptions of coded values in a column are maintained in value description tables. There are two types of values description tables - character value description table (char.vdt) and integer value description table (int.vdt).
Library attribute table (lat)	The library attribute table describes the properties of each library in a database.
Coverage attribute table (cat)	The coverage attribute table contains properties for all coverages in the library.
Feature class attribute table (fcs)	The feature class attribute table contains properties for all feature classes in a coverage.
Geographic reference table (grt)	Geographic reference tables document the coordinate reference system used in a VPF database. These tables are also developed in accordance with DIGEST.
Data quality tables (dqt) and Data quality coverages (dq)	Data quality information is maintained by using data quality tables, and/or by using data quality coverages. The content of the data quality tables in VPF is developed in accordance with DIGEST. The data quality coverages support the graphical portrayal of spatial variations in data quality across the geographic extents of VPF databases, libraries, and coverages.
Reference coverages  (tileref and libref)	The tile reference coverage is a VPF coverage that describes the tiling scheme of a tiled coverage. The library reference coverage serves as an index or reference map for the coverage. The tile reference coverage is required for tiled libraries, whereas the library reference coverage is optional for both tiled and untiled libraries.
Note   You can view the metadata files as tables in ArcView. See Adding a VPF table in ArcView.

See also

Working with VPF data in ArcView


Working with VPF data in ArcView

Using ArcView’s VPF Viewer extension, you can now integrate VPF databases into your work seamlessly, without first having to convert these files into ArcView shape file format. You can directly add VPF themes in ArcView. Adding a VPF theme is similar to adding any other feature theme from a shape file or an ARC/INFO coverage.

Loading the VPF Viewer extension

The VPF support in ArcView is implemented as an extension. You must first load the extension before you can add VPF databases to your map.

To load the VPF Viewer extension

1	Start ArcView and make the Project window active.

2	From the File menu, choose Extensions.

3	In the Extensions dialog, click the check box next to the VPF Viewer extension.

4	Press OK

Adding VPF themes to a map

In ArcView, working with VPF coverages (contained in a VPF library) is similar to adding themes from ARC/INFO coverages. To add VPF data to your view, see Adding a VPF theme.

Working with VPF tiles (tiled coverages)

Tiling is a scheme by which a large database is subdivided into smaller and more manageable components. A coverage subdivided in such a manner is referred to as a tiled coverage. Although each tile is stored separately in sub-directories, the logical interpretation of a tiled coverage is identical to that of an untiled one. In other words,  you can use a tiled coverage as a single theme with an associated attribute table. The advantage of using a tiled coverage is that you can limit the spatial extent of the coverage to the desired subset of tiles. This will considerably increase the drawing speed. You use the Area of Interest tool [image] in ArcView to draw features from selected tiles. See working with VPF tiled coverages.

Working with VPF tables

Every VPF theme has an associated feature attribute table. In addition, you can add several associated VPF tables in ArcView. See Adding a VPF table in ArcView.

Symbolizing VPF themes

When you add a VPF theme, ArcView uses a default symbol to draw features. In order to explore, understand, and make meaningful maps, you need to classify features based on the theme’s attributes. ArcView supports a variety of symbolization tools that you can use to symbolize VPF themes. To learn more about thematic mapping tools, see types of thematic maps.

Projecting the VPF data

Map projections allow areas on the surface of the Earth (a spheroid) to be represented on a map (a flat surface). In this way the precise position of features on the Earth's surface can be obtained from the map. ArcView supports a variety of map projections to view your VPF data. To set the map projection for your view, see Setting the map projection.

Controlling the VPF theme properties

You can control various theme characteristics such as the theme's name, what the theme contains, how it is displayed in the view, etc., in the view's Table of Contents. See Setting a theme’s properties.

Working with 3D VPF data

The VPF Direct Read function has been given the ability to add valid 3D VPF Themes as 3D type files. A valid 3D VPF theme is one where there are no null Z values present in the coordinate geometry. If any null values are found in the geometry, the theme will be added to the view as a 2D type file.

Adding a 2D or 3D VPF theme to a 3D Analyst view

The VPF Direct Reader will automatically detect whether a VPF theme is 3D and add it accordingly. To view the shapefiles in full 3D, you must have the 3D Analyst extension loaded.

Because the 3D Analyst contains an independent view, it does not recognize the Area of Interest (AOI) defined by ArcView. See working with VPF tiled coverages for more information about the Area of Interest. If tiled VPF themes are added directly to the 3D view, the user will initially see only one selected tile. To add a 3D VPF theme with the Area of Interest defined, follow the instructions below.

To add a 3D VPF theme with the Area of Interest defined

1	Add a VPF theme to a normal 2D ArcView view.

2	Set the AOI (Area of Extent) to the tile locations that you wish to view.

3	Use the Copy Themes menu item to copy the selected themes into the clipboard.

4	Open a 3D Analyst view and use the Paste menu item to paste the 3D VPF theme into the 3D Analyst view.


Working with VPF tiled coverages

Tiling is a scheme by which a large database is subdivided into smaller and more manageable components. A coverage subdivided in such a manner is referred to as a tiled coverage. Although each tile is stored separately in sub-directories, the logical interpretation of a tiled coverage is identical to that of an untiled one. In other words,  you can use a tiled coverage as a single theme with an associated attribute table. The advantage of using a tiled coverage is that you can limit the spatial extent of the coverage to the desired subset of tiles. This will considerably increase the drawing speed. You can use ArcView’s Area of Interest tool to modify the extent of the tiles. As you change the area of interest, ArcView automatically updates the theme (and its associated attribute table)  to draw features from selected tiles.

Area of Interest

Setting the area of interest for a view sets the spatial extent for all VPF themes in the view. When you set an area of interest, only those VPF library tiles that are within or overlap the extent will display in the view. The feature tables of all the VPF themes in the view are updated when you set an area of interest so that only the records of the visible tiles are represented in the table.

By default the area of interest for a view is not set. When a VPF theme is added to a view where the area of interest has not been set, only the center tile of the library will be displayed.

You may add a theme that you can use as a reference when setting the desired area of interest. For VPF libraries, you can use the Tile Reference coverage. This coverage appears as a choice when you add a theme from VPF library.

Setting the Area of Interest

ArcView provides several ways to set the area of interest.

 Interactively using the Area of Interest tool

 Based on another theme, the view extent, the display extent, or an extent you type in explicitly. The Area of Interest dialog box contains a drop-down list of possible extent settings. You can access this dialog using the Area of Interest button in the View Properties dialog.

Notes

 You can add themes from multiple VPF libraries. However, a view can only have one area of interest.

 Any action which has been performed on the theme, such as a table join, field index, or theme definition, will be re-executed each time the area of interest is reset.