Professional PHP library for reading SRTM (HGT) files with high precision and minimal memory footprint. Designed for modern PHP 8.2+ with an emphasis on SOLID principles and flexibility.
- Extremely low memory footprint: Uses
fseekfor direct data access without loading entire files into RAM. - High precision: Implements bilinear interpolation for accurate elevation calculation between measurement points.
- Flexible architecture: Abstraction of data sources (DataSource) and tile providers (TileProvider).
- Resolution support: Full support for both SRTM-1 (1 arc-second) and SRTM-3 (3 arc-seconds).
You can install the library via Composer:
composer require tito10047/hgtreaderuse Tito10047\HgtReader\HgtReader;
use Tito10047\HgtReader\Resolution;
use Tito10047\HgtReader\TileProvider\LocalFileSystemTileProvider;
// 1. Set the path to the folder containing .hgt files
$hgtPath = __DIR__ . '/data/hgt';
// 2. Create a tile provider (TileProvider)
$provider = new LocalFileSystemTileProvider($hgtPath);
// 3. Initialize the reader (Resolution is auto-detected from file size)
$reader = new HgtReader($provider);
// 4. Get precise elevation for coordinates
$lat = 49.38628;
$lon = 19.37702;
$elevation = $reader->getElevation($lat, $lon);
echo "Elevation: {$elevation} m";The library is ideal for generating elevation profiles of tracks, terrain analysis, or visualizing geographical data.
Example of track elevation profile rendering.
Detailed visualization of terrain changes.
If you need to read data from memory (e.g., during network transfers), you can use MemoryDataSource:
use Tito10047\HgtReader\DataSource\MemoryDataSource;
// ...
$content = file_get_contents('path/to/file.hgt');
$dataSource = new MemoryDataSource($content);For more detailed data (3601x3601 points), simply change the resolution:
$reader = new HgtReader($provider, Resolution::Arc1);The original static interface is available for existing projects:
// The old way of calling is still functional via a wrapper
HgtReader::init(__DIR__ . '/data/hgt', 3); // 3 for SRTM-3
$elevation = HgtReader::getElevation(49.38, 19.37);You can obtain data in .hgt format from various sources, for example:
The project is fully covered by tests using PHPUnit:
./vendor/bin/phpunit testsThis project is licensed under the Apache-2.0 License - see the LICENSE file for details.
Author: Jozef Môstka