The Raster Roam Search will display the requested NGA standard raster product over the area of interest. An area can be selected by clicking on the image map, providing a center point, or by defining the center point using the GEOnet Names Server.
The user can select the NGA standard raster products of Compressed Arc Digitized Raster Graphics (CADRG) - ONC, TPC, JOG; Digital Orthorectified Image (DOI) - 10M; and Digital Terrain Elevation Data (DTED) - Level 0;
Lat/Lon (decimal degrees or degrees minutes seconds), Universal Transverse Mercator (UTM), or Military Grid Reference System (MGRS) is requested for the center point. The decimal degree coordinate values should be positive for North and East values and negative (-) for West and South values . (examples: 34.5 and -15.2.) NOTE: To enter "0" (zero) as a latitude or longitude value use "-0" (minus zero) or "0." (zero period).
If the latitude and longitude of the desired point is unknown use the Geonames Query to establish the value or click the area in the image map.
Use the text entry field to enter the correct spelling of a geographic name. If you are uncertain of the correct spelling, use the wild card to enter single or multiple
letters. The Geonames wild card is the asterisk (*). An example using Boston is B*s*n, where the first * takes the place of the "o" and the second * takes the place of
"to". (Boston is a town in the United Kingdom located at 52 degrees 59 minutes north latitude by 0 degrees 1 minute west longitude.) For letters with diacritics, enter
the base letter only (without diacritic marks). For special characters, enter the equivalent conventional letter(s) or use the wild card.
Single or multiple countries may be selected (highlighted) within the scrollable window. To select countries separated on the list, select the first country, then press
and hold down the "Control" key. Continue to select countries. When you are finished selecting, release the "Control" key. The selected countries remain selected in
the scrollable window.
To deselect a country, hold down the "Control" key and click on the highlighted country.
(CAUTION: If you select another country when others are highlighted after you have released the "Control" key, the other countries will be deselected. Press the
"Control" key before selecting additional countries.)
Following each country in parentheses is the two letter Federal Information Processing Standard 10-3 Country Code and year of the last NGA gazetteer published
for that country. This date provides an indication of data currency for names records of that country.
If the center point was determined by a city name the first line of information will be about that selection. Explaination of results of a search by city name.
Ways to navigate around the data
Use the direction buttons to move a full screen
Click within the image to select a new center point
Enter a new center point in the coordinate fields and hit the Roam button to activate the change
Ways to change the data view
Image Size changes the amount of the data that is shown on the screen (depend on screen resolution, not the product scale.) Approximate sizes for 2 common screen resolutions:
Lat/Lon are displayed for the center coordinate point, these values can be changed and the new values will take effect when the Roam button is hit. The coordinates can be displayed in:
The height value is interpolated from DTED or DBDB-V and is in the WGS84 datum (if there is no DTED over the Center Coordinate "NO DATA" will be returned to the screen) (if the data is DBDB-V and the Center Coordinate is over land then "LAND" will be returned to the screen). The value can be displayed as:
The user can select the NGA standard raster products of Compressed Arc Digitized Raster Graphics (CADRG), Digital Orthorectified Image (DOI), and Digital Terrain Elevation Data (DTED).
Depending on the product type the user can select displayed properties.
DOI displays the type of Image Enhancement.
DTED displays the Sun Position of the shaded relief image.
Saving the area to another format using the Raster Importer
Select the format desired from the drop down list of available formats. The required file extension for that format is also displayed.
Type the desired file name, including the extension, in the output file box.
Click the import button to begin downloading your file.
When this checkbox is selected then the current lat/lon is stored as the starting ("From") point in the Range/Bearing (Distance/Azimuth) computation.
Once this point is stored then the distance and azimuth can be computed to the current center point by hitting the 'Compute Azimuth and Range' button in the Range Bearing Computations section
For the current center point and selected Shapefile layers the attributes can be displayed by entering the pixel search range and selecting the type of features.
This will display the meta data for the current view. For CADRG and DOI this will be a display of the attributes for all the frames that make up the area. For DTED this will be a display of the header information of all the cells the make up the area.
The Range Bearing Inverse Computation will display the forward azimuth (bearing), back azimuth (bearing) and range (distance) in meters as derived from the starting point and end point.
Select a starting point - click the desired starting point in the locator map. This will recenter the map on the selected starting point. Below the map select "Set this point as the starting ("From") Range Bearing Point."
Select an ending point or destination - Click the desired ending point in the locator map. This will now recenter the map on the selected ending point.
Scroll down the page to Range Bearing Computations
Set the range (distance) units - the units can be meters, kilometers, nautical miles, statute miles, or feet.
The Range Bearing Forward Computation will display the Latitude and Longitue for the location calculated using the starting point, azimuth and distance provided.
Select a starting point - click the desired starting point in the locator map. This will recenter the map on the selected starting point.
Scroll down the page to Range Bearing Computations
NGA Raster Roam Help
