Digital Topographic Data Base � 1998 (DTDB) - Information

The Digital Topographic Data Base - 1998 (DTDB98) is a digital representation of natural and cultural features of New Brunswick, organized into 1894 map windows (or files). It is made up of two databases: the Digital Terrain Model (DTM) Data Base and the Enhanced Topographic Base (ETB).

The ETB, containing graphic files and attribute files, is used to create a planimetric map; however, the DTM data has no attribute files, and is a digital representation of elevations though the Province. Each of the 1894 files in the DTDB represents a 1:10,000 window encompassing 0.1 degree in longitude (7.5 kilometres) by 0.05 degree in latitude (5.5 kilometres).

	Enhanced Topographic Database (Downtown Fredericton)

What is included with the ETB?

The ETB files are organized in 1:10,000 map windows and consists of:

• Graphic Files that contain geographic features (roads, lakes, rivers, buildings, etc).
• Attribute Files that contain descriptive text for some of the geographic features (road and hydrography attributes

ETB files contain topographic features organized into nine general categories: Buildings, Designated Areas, Delimiters, Land Cover, Land Features, Transportation (Road/Railroad), Structures, Utilities and Hydrography. Transportation and Hydrography are each maintained in their own files. The remaining seven general categories are maintained in one file.

What is included with the DTM?

	Digital Terrain Model Database (Downtown Fredericton)

The DTM Data Base is a digital representation of elevations organized into individual DTM files with the same 1:10,000 windows used for the ETB. There are no attribute files associated with these files. The DTM files contain elevation mass points, check points, and spot heights.

Spatial Framework

• Reference System:     North-American Datum 1983 (CSRS)
• Projection:                Stereographic Double
• Resolution (X,Y):       1.0 metre
• Resolution (Z):          0.1 metre
• Nominal Scale:          1:10,000
• Accuracy:                 +/- 2.5 metres for well-defined features

File Naming Convention

The naming convention for the DTDB files is based on the latitude and longitude (expressed in decimal degrees) of the Southeast corner of the 1:10,000 windows. These file names are coded as follows:

   aaaabbbb, where

• aaaa is the North latitude of the Southeast window corner, expressed as a 4-digit integer number in decimal degrees to the nearest 0.01 degree.
• bbbb is the West longitude of the Southeast window corner, expressed as a 4-digit integer number in decimal degrees to the nearest 0.01 degree.

For example, the DTDB file name for the window having its Southeast corner at latitude 46� 00� 00�� N (or 46.00) and longitude 66� 54� 00 E (or 66.90) is 46006690.

Available for Download�

Here are the downloadable DTDB file packages:

• Enhanced Topographic Base � 1998 (ETB98)
  
  The ETB98 files are available in three formats, all of which are packaged in a compressed file:

• Autodesk Data Exchange Format (DXF)
• CARIS GIS ASCII Format
• ESRI Shapefile Format

The downloadable DXF file package contains three DXF files:

• filename.gxf = General Theme
• filename.hxf = Hydrography Theme
• filename.rxf = Road Theme

The downloadable CARIS GIS file package contains three CARIS ASCII files plus three attribute files:

• filename.198 = Road Theme
• filename.398 = Hydrography Theme
• filename.g98 = General Theme
• filename.h98 = Hydrography Attribute File
• filename.n98 = Department of Natural Resources Road Attribute File
• filename.r98 = Road Attribute File

The dowloadable ESRI Shapefile package contains three groups of files:

• filename_g*.* = General Theme
• filename_g_l.* = General Line Features
• filename_g_p.* = General Point Features
• filename_g_r.* = General Polygon Features


• filename_h*.* = Hydrography Theme
• filename_h_l.* = Hydrography Line Features
• filename_h_p.* = Hydrography Point Features
• filename_h_r.* = Hydrography Polygon Features


• filename_r*.* = Road Theme
• filename_r_l.* = Road Line Features
• filename_r_p.* = Road Point Features
• filename_r_r.* = Road Polygon Features

For each file package, there are drawing and attribute support files available in the Support section. We highly recommend that you download these support files, they will help with the correct display of the information.


• Digital Terrain Model (DTM) Data Base
  
  The elevation data files are available in two formats, each packaged in a compressed file:

• CARIS GIS ASCII
• XYZ Text File

The downloadable CARIS GIS file package contains one graphic CARIS ASCII files:
• filename.d98 = Elevation mass points, check points, and spot heights

The downloadable XYZ file package contains one text file:
• filename.xyz = Positional coordinates and elevation value for each of the mass points, check points, and spot heights

Please note: For more information on the Digital Topographic Data Base (DTDB), please use the Communication section on the Geographic Data & Maps � Main Page.