A separate application in the family of amateur navigation tools GaladrielMap, which uses cartographic materials to monitor the depth ahead as the vessel moves, and if the depth is less than specified, sends a message to gpsdPROXY, to the GaladrielMap navigation server. The navigation server, in same way, generates a danger warning, which is perceived by the GaladrielMap chart plotter and is displayed on the chart.
Technically, this is a separate daemon that can run on the same machine as gpsdPROXY or on another machine on the same local network. The application is not necessary for navigation function and can be launched if necessary and computing resources are available.
To track the depth, a user-specified depth map in the Digital Elevation Model (DEM) format is used. Unfortunately, such maps are not very common, and we know of only one free project with such maps: Seascape. It is currently in the process of development, and the materials available there are not suitable for navigation. However, work is being carried out.
Anyway:
No information issued or not issued by this program can be the basis for any action or inaction by the vessel operators
and, of course, the author is not responsible for anything.
- The user-specified DEM data source. This can be either an online source or GaladrielCache (offline). The latter, of course, is preferable.
- Automatic start - stop. By specifying gpsdPROXY in the configuration the launch line of the application, you don't have to worry about launching it. Also, the application will terminate if gpsdPROXY terminates naturally, which saves computing resources. If gpsdPROXY terminates unnaturally or if the connection is lost, the application will try to reconnect to gpsdPROXY.
- High performance and low requirements for computing resources.
PHP > 7.2 with GD library. If you have DEM files that are not in webp format, then any version of PHP 7 will work. In the PHP 8 should work.
gpsdPROXY version >= 1.5
GaladrielMap version >= 3.5
Just copy the files.
The configuration file params.php contains comprehensive comments for successful configuration. You will need to specify the current network addresses of gpsdPROXY and the DEM data source.
Remember that this is a PHP program and requires compliance with the syntax of the language.
php depthCheck.php