ExternalExec
Properties
| Property | Characteristic | Dimension | Description |
|---|---|---|---|
| Command | compulsory, user-defined, default: empty |
1 | The command to be executed at a given iteration. |
| Environment | compulsory user-defined, default: empty |
2 | The set of environment variable definitions as required by the specified command for the given iteration. |
Supported Image & Pipeline Features
| Characteristic | Details |
|---|---|
| Image dimensions | n/a |
| Multi-band images | n/a |
| Pipeline role | stand alone |
| Sequential processing | n/a |
| Parallel processing | n/a |
Overview
ExternalExec enables the integration of commandline-based programs or scripts into a LUMASS model (workflow). When ExternalExec is executed, LUMASS launches a separate process, establishes the specified Environment and executes the specified Command. Comannd output is forwareded to either the model’s log file or the Notifications window, depending on whether the model is run by the lumassengine or the LUMASS desktop (GUI) program.
Command Specification
The Command property can be used to specify any commandline-based program or script including its arguments that runs on the computer LUMASS is being executed on. The example below shows how LUMASS utilises a small utility script to run the gdal_rasterize command.
ExternalExec’s Command property
Environment Variable Definition
Environment variables for a given command for a given iteration are specified as <var_name>=<value>, e.g.
MY_OUTPUTDIR="/home/geoprocessor/outputs/scenario_1"
Evironment variable definition
External Utility Scripts
LUMASS ships with a small number of external utility scripts that execute certain externally provided functionality, such as GDAL applications or operating system commands. All scripts carry the *.bat file extension to enable model portability across Windows and Linux platforms. The scripts can be found in the usr/utils subidrectory of the LUMASS AppImage mountpoint, e.g. /tmp/.mount_lumassgWSfhy, on Linux or in the utils subdirectory of the main LUMASS folder, e.g. lumass-0.9.66, on Windows. On both systems, the path can be accessed from within a model with the LUMASS expression $[LUMASS:LUMASSPath]$/../utils (cf. ExternalExec’s Command property).
| Script | Functionality | Synopsis |
|---|---|---|
| del.bat | Deletion of files | del.bat <path> <file> |
| gdal_polygonize.bat | Vectorisation of images (raster) | s. gdal.org |
| gdal_rasterize.bat | Rasterisation of vectors (shape files) | s. gdal.org |
| ogr2ogr.bat | Vector file format conversion | s. gdal.org |
Important While LUMASS for Windows provides all necessary libraries and programs to successfully execute these scripts, Linux users need to install GDAL to utilise its functionality.