Use

Use#

WindMapper may be run in one of two modes:

  1. download a SRTM tile that corresponds to a lat/long bounding box defined by the user or;

  2. use a user-supplied DEM

Two examples are given, one for each use case. These are available in the source tree under examples.

Download#

The example given in examples/download_DEM can be run as

wind_mapper_generic.py examples/download_DEM/param_download_DEM.py

Existing#

The example given in examples/existing_DEM can be run as

wind_mapper_generic.py examples/download_DEM/param_existing_DEM.py

Output#

Once Windmapper has run, the output folder will have a set of files:

ref-DEM-utm.tif#

The entire domain to be run on

tmp_X_Y.tif#

Windmapper tiles the domain to ensure a tractable solution. Each tile will be named tmp_X_Y.tif for example tmp_0_0.

ref-DEM-utm-*.vrt#

A VRT file is an xml meta-file that is a collection of underlying rasters that make up a larger raster. These underlying rasters are in the tmp_dir_X_Y directories. The number in the vrt name, e.g., 180 in ref-DEM-utm_180_V.vrt is the direction the wind comes from. The U/V refer to either the U or V component speedup. And the _spd_up_X suffix, e.g., _spd_up_1000, is the wind speed (\(W=sqrt(U^2+V^2)\)) with the given averaging distanced as specified in the configuration (1000 m default).

Troubleshooting#

MPI slots#

If an error about MPI slots is raised, set the MPI_nworkers configuration parameter to a smaller number. If it hasn’t been set, set it to 1 or 2 less than the slots reported in the error. On single-core machines you will need to enable oversubscription. This can be done for OpenMPI

export OMPI_MCA_rmaps_base_oversubscribe=true; windmapper.py my-config.py

or by pernamentally enabling it

echo rmaps_base_oversubscribe=true >> $HOME/.openmpi/mca-params.conf

More details can be found here mpi4py/mpi4py#441

GDAL#

If you recieve an error about GDAL _gdal_array, like:

 Traceback (most recent call last):
  File "/Users/runner/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/windmapper_utls/MPI_call_WN_1dir.py", line 190, in <module>
    main(*sys.argv[1:])
  File "/Users/runner/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/windmapper_utls/MPI_call_WN_1dir.py", line 178, in main
    call_WN_1dir(WINDNINJA_DATA, gdal_prefix, user_output_dir, fic_config_WN, list_tif_2_vrt, nopt_x, nopt_y, nx,
  File "/Users/runner/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/windmapper_utls/MPI_call_WN_1dir.py", line 105, in call_WN_1dir
    ang = gtif.GetRasterBand(1).ReadAsArray()
  File "/Users/runner/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/osgeo/gdal.py", line 5278, in ReadAsArray
    from osgeo import gdal_array
  File "/Users/runner/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/osgeo/gdal_array.py", line 10, in <module>
    from . import _gdal_array
ImportError: cannot import name '_gdal_array' from 'osgeo' (/Users/runner/hostedtoolcache/Python/3.8.18/x64/lib/python3.8/site-packages/osgeo/__init__.py)

Then force the reinstall of gdal via

python -m pip install --no-cache-dir --force-reinstall gdal[numpy]

This error results from gdal being install after numpy.

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