Import a VMAP Level 1 File

VMAP Level 1 is the most detailed public domain digital map of international regions currently available. See the Import Drawing - VMAP topic for a discussion of VMAP. VMAP levels 0 and 1 are products of the former National Imagery and Mapping Agency (NIMA) of the United States, renamed in a fit of bureaucratic irrelevance to the National Geospatial-Intelligence Agency, NGA. NIMA used to provide VMAP for free download. NGA may or may not make VMAP available for download.

 

Step 1: Download the Data

 

Visit the NGA site at http://www.nima.mil and drill down to their geodata downloads page (currently at http://geoengine.nima.mil). NIMA may choose to change their site at any time so this topic does not provide a detailed description of how to locate and download data from NIMA's site. If for any reason NGA no longer provides VMAP, users should file a Freedom of Information Act request to obtain this data.

 

If given a choice of formats, choose "VMAP Level 1 in Mil-Spec" format using "G-zipped" compression.

 

Note: Manifold reads all of NIMA's military formats. When downloading data from NIMA choose the Mil-Spec or Military Specification formats for all data. This will provide the data in its original form.

 

For this example we will zoom into Central America and download VMAP Level 1 as a Mil-spec, G-zipped file. The result will be the download of an approximately 100-megabyte file called v1155.tar.gz. At the present time NIMA is providing its VMAP1 downloads as large files, each of which corresponds to the compressed content of one of the VMAP1 CDs. The v1155.tar.gz file corresponds to VMAP 1 ("v1") CD 155. There are over 200 CDs in the complete VMAP1 data set.

 

Step 2: Unzip / Extract the Files

 

A .gz file is a "gnu-zipped" file that uses open source software to perform compression similar to Windows .zip files. .tar files are UNIX files that are created by the TAR ("tape archiver") program, which performs a function in UNIX similar to that of the arj program in DOS and UNIX. TAR can take many files organized in directories and combine them into a single file. It's a handy way of bundling related files together for transmission. .tar files must extracted into the many smaller files that comprise them.

 

When we download v1155.tar.gz from NIMA's site, what we've downloaded is a .tar file (a collection containing numerous files inside the .tar file) that has been further compressed into a .gz file. We can decompress the .gz and also extract the .tar file it contains using WinZip.

 

To do this, place the v1155.tar.gz file into a folder and double click it [assuming, of course, you've already installed WinZip on your system]. Note: before using WinZip to decompress files of this type, launch WinZip and make sure that WinZip's Option - Configuration - Miscellaneous tab does not have a check for "TAR file smart CR/LF conversion."

 

images\eg_import_vmap_01.gif

 

WinZip will open the .gz and see the compressed .tar file it contains. It asks us if we want to decompress it and open the .tar file. Click Yes. The following decompression process may take a while on a slow machine. WinZip will then display all of the files in the .tar file. Extract them all to a convenient directory, preferably named for the originating file. For example, we would extract all of the files from v1155.tar.gz into a directory called v1155.

 

Step 3: Import into Manifold

 

Launch Manifold. Before importing, create a folder in the project pane named v1155. Importing VMAP results in a huge number of files, so it is best to keep them organized within their own folder in the project pane.

 

To import, choose File - Import - Drawing and choose VMAP Files (dht) in the Files of Type box. Browse over to the folder where you placed the files extracted from v1155.tar.gz, browse down into the directory tree into the soamafr folder and double-click on the dht file that is located there.

 

images\eg_import_vmap_02.gif

 

The dht file is a catalog of what is available within the numerous files in various subdirectories below it. The Import VMap Data Set dialog allows us to choose which data we wish to import. For this example, we will choose Hydrography and Transportation and press OK.

 

images\eg_import_vmap_03.gif

 

A seemingly endless list of components is created in the project pane within two folders named Hydro and Trans. Two maps named Hydro and Trans are created as well. The two maps group the various hydro and trans drawings within a map for convenience. We can open these maps or open individual drawing or labels components.

 

images\eg_import_vmap_04.gif

 

The 1155 file covers a very large area because it includes a data set that is normally provided on the VMAP1 155 CD. The illustration above shows the hydro map zoomed in to central Panama with all layers but the Hydrotxt_lib_155_hydro layer turned on.

 

images\eg_import_vmap_05.gif

 

Applying some formatting can help comprehension. The scene above shows Costa Rica near the border with Panama. The lines in the Watrcrsl_lib_155_hydro layer have been formatted in blue color.

 

images\eg_import_vmap_06.gif

 

VMAP1 imports into Manifold as georegistered drawing so it is easy to combine them with other georegistered components in maps. For example, we can download and import the DTED Level 0 data for this region and drag and drop the resultant surfaces into the map to create the scene above. We've also formatted the labels for greater visibility.