Derive stokes parameters (stokes_parm)#

polsartools.stokes_parm(SxxFile, SxyFile, win=3, fmt='tif', cog=False, ovr=[2, 4, 8, 16], comp=False, max_workers=None, block_size=(512, 512), progress_callback=None)[source]

This function computes the Stokes parameters and child parameters from Single look Scattering Matrix elements.

Examples

>>> # Basic usage with default parameters
>>> stokes_parm("/path/to/s11.bin", "/path/to/s12.bin")

>>> # Advanced usage with custom parameters
>>> stokes_parm(
...     "/path/to/s11.bin",
...     "/path/to/s12.bin",
...     win=5,
...     fmt="tif",
...     cog=True,
...     block_size=(1024, 1024)
... )
Parameters:

  • SxxFile (str) – Path to the Sxx file.

  • SxyFile (str) – Path to the Sxy file.

  • win (int, default=3) – Size of the spatial averaging window.

  • fmt ({'tif', 'bin'}, default='tif') – Output file format: - ‘tif’: GeoTIFF format - ‘bin’: Raw binary format

  • cog (bool, default=False) – If True, creates a Cloud Optimized GeoTIFF (COG) with internal tiling and overviews for efficient web access.

  • ovr (list[int], default=[2, 4, 8, 16]) – Overview levels for COG creation. Each number represents the decimation factor for that overview level.

  • comp (bool, default=False) – If True, applies LZW compression to the output GeoTIFF files.

  • max_workers (int | None, default=None) – Maximum number of parallel processing workers. If None, uses CPU count - 1 workers.

  • block_size (tuple[int, int], default=(512, 512)) – Size of processing blocks (rows, cols) for parallel computation. Larger blocks use more memory but may be more efficient.

Returns:

  • None

  • Writes stkokes and child parameters to disk –

    • stokes_g0 (.bin or .tif)

    • stokes_g1 (.bin or .tif)

    • stokes_g2 (.bin or .tif)

    • stokes_g3 (.bin or .tif)

    • stokes_e1 (.bin or .tif)

    • stokes_e2 (.bin or .tif)

    • stokes_e1norm (.bin or .tif)

    • stokes_e2norm (.bin or .tif)

    • stokes_phi (.bin or .tif)

    • stokes_tau (.bin or .tif)

    • stokes_x_poincare (.bin or .tif)

    • stokes_y_poincare (.bin or .tif)

    • stokes_H (.bin or .tif)

    • stokes_A (.bin or .tif)

    • stokes_contrast (.bin or .tif)

    • stokes_DoL (.bin or .tif)

    • stokes_DoCP (.bin or .tif)

    • stokes_LPR (.bin or .tif)

    • stokes_CPR (.bin or .tif)

Prepare DEM (prepare_dem)#

polsartools.prepare_dem(bbox, out_path='dem.tif', dem_type='SRTM1', hgt_dir='hgt_tiles', apply_correction=True, clip=True, clean_tiles=True)[source]

Prepares a Digital Elevation Model (DEM) from downloaded elevation tiles.

This function downloads elevation tiles based on a bounding box, mosaics them into a single raster, optionally applies ellipsoid height correction, clips to the bounding box, and saves the result as a GeoTIFF. Temporary tile files can be cleaned up after processing.

Examples

>>> bbox = (-70.2, 43.5, -66.2, 45.8)  # xmin, ymin, xmax, ymax
>>> prepare_dem(bbox, out_path="SRTM1_mosaic_clip.tif")
>>> prepare_dem(bbox, out_path="SRTM3_mosaic_clip.tif", dem_type="SRTM3")
Parameters:

  • bbox (tuple of float) – Bounding box in the format (xmin, ymin, xmax, ymax), in geographic coordinates (longitude, latitude).

  • out_path (str, optional) – Path to save the output DEM GeoTIFF file. Defaults to “dem.tif”.

  • dem_type (str, optional) – Type of DEM source. Options include “SRTM1”, “SRTM3”, “COP30”, “COP90”. Defaults to “SRTM1”.

  • hgt_dir (str, optional) – Directory to store downloaded tiles. Defaults to “hgt_tiles”.

  • apply_correction (bool, optional) – Whether to apply WGS84ellipsoid height correction to SRTM tiles. Defaults to True.

  • clip (bool, optional) – Whether to clip the output DEM to the bounding box. Defaults to False.

  • clean_tiles (bool, optional) – Whether to delete the tile directory after processing. Defaults to True.

Returns:

The function saves the DEM to the specified out_path.

Return type:

None

Notes

  • Uses GDAL for mosaicking and warping.

  • Supports ellipsoid correction for SRTM1 and SRTM3.

  • Automatically creates empty tiles for missing SRTM1 data.