Derive stokes parameters (stokes_parm) — PolSARtools 0.10 documentation

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# 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)

  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)

  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.