DTED (Digital Terrain Elevation Data) Handler in GDAL

Overview

DTED is a military specification for storing terrain elevation data used by the U.S. Department of Defense and Geographic Information Systems. This implementation provides functionality to read and process DTED files through GDAL.

DTED Levels

DTED comes in three resolution levels:

• Level 0: Lowest resolution (~1km)
• Level 1: Medium resolution (~100m)
• Level 2: Highest resolution (~30m)

File Format

DTED Grid Example (3601x3601 pixels for Level 2):

   [1000m][1200m][900m]...
   [800m] [750m] [600m]...
   [500m] [450m] [400m]...

How This Code Works Core Features Opens DTED files using GDAL library Reads elevation data row by row Finds highest elevation point Converts grid coordinates to latitude/longitude Dependencies GDAL (Geospatial Data Abstraction Library) C++ compiler Installation

macOS (using Homebrew)

brew install gdal

Building

g++ -o find_highest_point find_highest_point.cpp $(gdal-config --cflags) $(gdal-config --libs)

Usage

./find_highest_point path/to/file.dt2

Code Structure

Main Components

DTEDHighPoint Class

• Handles file reading
• Tracks maximum elevation
• Converts coordinates

Data Processing

• Reads elevation data in 16-bit integers
• Scans entire grid for highest point
• Uses geotransform for coordinate conversion

Output Example

Highest point:

Elevation: 2500 meters
Location: 35.6789°N, 138.7654°E

Technical Details

Resolution

• DTED-2 (.dt2) files: 3601x3601 grid
• Each pixel represents ~30m on Earth's surface
• Elevation precision: 1 meter

Memory Usage

• Efficient row-by-row reading
• Only one scanline in memory at a time
• 16-bit integer storage per elevation point

Geographic Transformation

[x,y] grid coordinates → [latitude,longitude] using:

• Origin point (top-left)
• Pixel spacing
• Rotation parameters

DTEDDataset

Main class handling DTED file operations:

class DTEDDataset {
  char *pszFilename;
  DTED *psDTED;
  bool bVerifyChecksum;
  // ... other members
};

DTEDHighPoint

Class for finding elevation extremes:

class DTEDHighPoint {
  double maxElevation;
  double latitude;
  double longitude;
};

Features

1. File Operations

• Reading DTED files
• Accessing elevation data
• Metadata handling
• Coordinate transformations

2. Metadata Support

DTED_VerticalAccuracy
DTED_HorizontalAccuracy
DTED_VerticalDatum
DTED_HorizontalDatum

3. Configuration Options

GDAL_DTED_SINGLE_BLOCK=TRUE/FALSE  // Read mode
DTED_VERIFY_CHECKSUM=YES/NO        // Data validation

Usage Example

// Initialize DTED file handler
DTEDHighPoint finder;

// Process DTED file
if (finder.findHighestPoint("elevation.dt1")) {
  double elevation = finder.getMaxElevation();
  double lat = finder.getLatitude();
  double lon = finder.getLongitude();
}

File Structure

Header Information

• Origin coordinates
• Resolution data
• Security classifications
• Reference system info
• Data compilation details

Data Organization

• Column-major storage
• North-south profile alignment
• Elevation values in meters
• Special handling for no-data values

Dependencies

• GDAL core library
• C++ Standard Library
• Common Portability Library (CPL)

Technical Documentation

For detailed API documentation and implementation specifics, see:

• GDAL DTED Documentation
• DTED Format Specification

Notes

• Default horizontal datum: WGS84
• Elevation referenced to mean sea level
• Preserves security codes and partial cell indicators
• Supports both reading and limited writing capabilities

Building

cmake -DGDAL_ENABLE_DRIVER_DTED=ON ..
make

For development and testing, refer to CMakeLists.txt.