VPFView




VPFView 2.1 is the NIMAMUSE application that allows you to browse, display,and perform spatial queries on NIMA digital vector data in Vector ProductFormat (VPF). VPF data to be displayed are selected by features, which aresubsequently collected and saved into structures called views. Theview is the basic unit that VPFView uses to save and display parts of yourVPF data base. The features which are selected for inclusion in the viewand the visual representation of the these features are defined in a VPFViewsession.

As the diagram below shows, VPFView reads a VPF product, produces user-definedviews, and displays those views. The user built views can also be saved todisk, and subsequently be reloaded from disk for viewing at a later time.






Here are the major data manipulation activities in a VPFViewsession:



Digital Vector Data

Simply put, digital vector data are connected points that represent naturaland cultural geographic features. Various level of spatial relationship canbe represented in the vector data base. Typically, there is also descriptivedata (attributes) that can be associated with a vector feature.

NIMA digital vector data in VPF are arranged in various types of relationaldata base tables, which are stored as files. These files hold the varioustypes of features in VPF (area, line, point, text), and are arranged indirectories, which reflect the VPF structure.

The visual display of this vector data is entirely up to the user. You makethe decision on what features to display, their color, line weight, andannotations. Since VPF data is organized in layers (coverages), you can "stack"these layers at your discretion for display.

The simplified diagram below shows a simple vector data base, first as adisplayed picture, then as a table. In NIMA VPF products, the coordinatesare in units of latitude and longitude, and there are separate tables forarea, line, point and textual data.






VPF - Vector Product Format

Vector Product Format (VPF) is a georelational vector data model that definesa set of data structures (files and tables) containing data for digitalgeographic products. Any product in VPF will have all of its constituentdata (numeric and textual) stored in relational database tables. VPF is theNIMA standard format for vector data.


Vector databases can be large, so VPF is hierarchically organized. A VPFproduct is distributed as a database. The database can be dividedinto several libraries, which can be defined by geographic extent,scale, or some other user-defined criteria. An example of a library is theNorth American continent.

Libraries have one or more coverages. A coverage is a basic unit ofdata organization, and can be thought of as a separate layer of informationwithin a library. Boundaries, Rivers, and Transportation could all be examplesof coverages. In a VPF library, coverages have a common projection/coordinatesystem, a common scale, a common tiling scheme (if it is tiled), and a singlespatial extent.

Within a coverage there are feature classes. A feature class is agroup of related features. The Transportation coverage could be madeup of the Roads, Railroads, and Airports feature classes. A feature classis made up of geometric primitives and attributes. The primitivesdescribe the location of the features with coordinates, and attributes modelthe thematic information about the features. Attributes, primitives, andfeature classes are all stored in relational tables.

There are two kinds of relationships modeled by VPF: spatial (where)and thematic (what). Spatial relationships can exist among the primitives,and thematic relationships are based on attributes within a feature class.Primitives in a VPF database can have any of four levels of spatial relationship,referred to as topology. These levels range from having no relationship tohaving a normal two-dimensional planar topology. Planar topology handlesrelationships like adjacency, connectivity, intersection, containment andcomposition. Topology in VPF is defined at the coverage level.


Views and Themes

The purpose of VPFView is to allow the user to build elements calledviews and themes so the VPF data can be displayed in a meaningfulway. Views and themes are not part of any VFP database, they are only builtwithin the context of a VPFView session.

A theme is a user-defined classification from within a feature class basedon attribute values. The idea of a theme lets you select only what you areinterested in from within a particular feature class, and then handle itas an single grouping. In the second diagram below, a "Swamp" theme couldbe built from features with a "is a swamp" attribute value from featuresin the "Areas" feature class in the "Land Cover" coverage in the "LibraryX" library in the "Database" database. More select themes can be built witha combination of attribute values, such as "is a swamp" and "governmentprotected" could combine to build a "Protected Swamp" theme.

A view is a collection of themes with user-selected symbology and colors.A view is your custom-made view of your VPF database. More than one viewcan be constructed from a single VPF database, and views can be named andsaved by VPFView, and subsequently reloaded and displayed. Keep in mind thatany display of a view with VPFView requires that the original VPF data thatgenerated the view be directly accessible to the displaying platform.


Generalized View and Theme Diagram:





Example View and Theme Diagram:





* The VPFView Session

The VPFView Session is characterized by three display windows: a large Mapwindow, a Library Reference window, and a Feature Selection window. Allactivities and functions will originate from pulldown menus on top of theMap and Library Reference windows, and from function buttons on the bottomof the Feature Selection window. These three windows will appear togetherupon startup of VPFView in Screen Layout Mode 3, or one at a time in ScreenLayout Mode 1. There is a picture of these windows in Screen Layout Mode3 below in " A look at the VPFView Session".


Some Preparation Before Run VPFView

Before your VPFView Session begins:

(1)  VPFView is automatically installed on your hard drive whenyou install NIMAMUSE 2.1.

(2)  Refer to the VPFView v2.1User's Guide, section 3, Starting VPFView, on how to start VPFView onyour platform (UNIX, Windows).

(3)  Determine Screen Layout Mode (3 or 1) that your hardwarewill dictate. See the VPFView v2.1 User'sGuide , section 3, Default Screen Layout .

(4)  Know the pathname to your VPF data.

(5)  Be aware of attribute values for the construction of themes.



A look at the VPFView Session

The following is a look at a VPFView session for the purposes of identifyingthe functions available to the VPFView user. Contents of pulldown menus andpopup windows will be displayed. For a more thorough treatment of VPFView,and for tutorials, refer to the VPFViewv2.1 User's Guide.

Shown below is VPFView in Screen Layout Mode 3 from a Sun/UNIX platform.The large window on the left is the Map window, the window in the upper rightis the Library Reference window, and the window in the lower right is theFeature Selection window. The contents of the Map window is a view: it consistsof shoreline features in a box defined in the Library Reference window symbolizedby black lines.





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- Create a View

To create a new view in VPFView, select the "File/View/Create" pulldown choicefrom the Map window:




This choice presents the following popup menu used to identified the requiredVPF data that generates the view:



Be sure to put just the libraries you are interested in inside the "IncludedLibraries" box above. VPF Libraries are first identified by the followingFile Selection Box:




You will be asked to identify symbology for the view. Use the following FileSelection Box and choose any *.sym file to make all *.sym files known tothis view:




You must also identify a filename for your newly created view. In the boxbelow, the name of the view is "test1%":




After the above dialog windows have been satisfied, you will now see VPFViewdisplay the Map window, the Library Reference window, and the Feature Selectionwindow.



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- Load a View

To load and display a previously constructed view in VPFView, select the"File/View/Load" pulldown choice from the Map window:




Now identify the view to be loaded:



In this example, choose previously constructed view "test1%".

Keep in mind that the data used to create this view must still be in placeat the filename location when the view was created.


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- Building a Theme

In a Feature Selection window, you choose features for display by clickingthe check boxes on the left (below, Coastline/Shoreline is chosen; note thatmore than one feature may be chosen in a theme). Also, clicking on the symbolfor the feature allows you to change the symbology and color for the featurewithin the current theme. Click on "Apply" and/or "Draw" to update thetheme.



Click on "New Theme..." to begin building a new, named theme.


Below is an example of a dialog that build a new theme named "DisputedBoundaries". Set the appropriate Database, Library, Coverage and FeatureClass Entries. This theme is further refined by the expression "BST = 3",which refers to the BST (Boundary Status Type) attribute of features in thisFeature Class. The value of 3 means "In Dispute". Note that symbology canbe set here, too.




Click on the "Dictionary.." button to get the window below which displaysdatabase dictionary (feature codes and attribute value meanings) in a textwindow. This information helps you construct an expression in the windowabove that defines the theme.




Remember, too, that one or many themes define a view in VPFView.



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- Map Properties

At the top of the large Map window, click on the "Properties..." button todisplay properties of the current view display window. In this window, youcan also set some display options as well. See the Map Properties examplebelow:




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- Spatial Query

VPFView can display attribute information of features that are portrayedin the large Map window. At the top of the Map window, click on "SpatialQuery..." button. Next, position the cursor on the feature you are interestedin and click. The feature will be graphically identified in the Window, anda popup window is presented with VPF and attribute information. The windowbelow shows the attributes for Edge 359 of a coastline feature:




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- Distance

VPFView gives you the ability to measure distances between points withinthe Map window. You enter this function by clicking the "Distance" buttonnear the top of the Map window. The cursor changes to a thin-lined cross,and your points are selected with mouse clicks. The distance between thetwo most recently selected and the total distance measured are reported atthe bottom of the Map window in the Status Bar. In the example below, fivepoints in a "W" pattern in the lower right of the Map window have been selected.The distances in this function are approximate, and the units of measurecan be set on the "Properties..." popup window. You end the session by pressingthe Escape key.





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- Library Reference Properties

Clicking the "Properties..." button in the Library Reference window givesyou options in the portrayal of this window.





A grid, tile boundaries, text and reference points may be added to the LibraryReference window by choosing check boxes in the Library Reference Propertieswindow, followed by clicking on "Apply":





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VPFView Tutorials

For VPFView tutorials, refer to sections 3, 4 and 5 in theVPFView User's Guide , VPFV_UG.DOC.


Reference

MIL-STD-2407, Military Standard Vector Product Format




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Related NIMAMUSE Documents


VPFView User's Guide   VPFV_UG.DOC

Vector Importer   VPF_IMP.DOC

Vector Importer Users Guide  VPFI_UG.DOC

Fusion   FUSION.DOC

Fusion Users Guide   FUS_UG.DOC

Access and Prepare NIMA Digital Data  APNDD.DOC

Build Your Own Map   BYOM.DOC

Run Specialty Applications   RSA.DOC

NIMAMUSE 2.1 Documentation   INTRO.DOC