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radar_grid

file_to_rdr_grid(ref_grid_path)

read parameters from text file needed to create radar grid object

Source code in src/compass/utils/radar_grid.py 
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def file_to_rdr_grid(ref_grid_path: str) -> isce3.product.RadarGridParameters:
    '''read parameters from text file needed to create radar grid object'''
    with open(ref_grid_path, 'r') as f_rdr_grid:
        sensing_start = float(f_rdr_grid.readline())
        wavelength = float(f_rdr_grid.readline())
        prf = float(f_rdr_grid.readline())
        starting_range = float(f_rdr_grid.readline())
        range_pixel_spacing = float(f_rdr_grid.readline())
        length = int(f_rdr_grid.readline())
        width = int(f_rdr_grid.readline())
        # read date string and remove newline
        date_str = f_rdr_grid.readline()
        ref_epoch = isce3.core.DateTime(date_str[:-1])

        rdr_grid = isce3.product.RadarGridParameters(
            sensing_start, wavelength, prf, starting_range,
            range_pixel_spacing, "right", length, width,
            ref_epoch)

        return rdr_grid

get_decimated_rdr_grd(rdr_grid_original, dec_factor_rng, dec_factor_az)

Decimate the rdr_grid_original by the factor close to dec_factor_rng and dec_factor_az in range / azimuth direction respectively, while making sure that the very first / last samples / lines in rdr_grid_original gets included in the result.

Parameters:

Name Type Description Default
rdr_grid_original

The original radargrid as the basis of the decimated radargrid

 required
dec_factor_rng

Decimation factor in range direction

 required
dec_factor_az

Decimation factor in azimuth direction

 required

Returns:

Name Type Description
rdr_grid_decimated RadarGridParameters

Decimated radar grid
Source code in src/compass/utils/radar_grid.py 
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def get_decimated_rdr_grd(rdr_grid_original,
                          dec_factor_rng,
                          dec_factor_az) -> isce3.product.RadarGridParameters:
    '''
    Decimate the `rdr_grid_original` by the factor close to
    `dec_factor_rng` and `dec_factor_az` in range / azimuth direction respectively,
    while making sure that the very first / last samples / lines in
    `rdr_grid_original` gets included in the result.

    Parameters
    ----------
    rdr_grid_original: isce3.product.RadarGridParameters
        The original radargrid as the basis of the decimated radargrid
    dec_factor_rng: int
        Decimation factor in range direction
    dec_factor_az: int
        Decimation factor in azimuth direction

    Returns
    -------
    rdr_grid_decimated: isce3.product.RadarGridParameters
        Decimated radar grid
    '''
    rdr_grid_decimated = rdr_grid_original.copy()
    rdr_grid_decimated.width = int(np.ceil(rdr_grid_original.width / dec_factor_rng))
    interval_rng = (rdr_grid_original.width - 1) / (rdr_grid_decimated.width - 1)

    rdr_grid_decimated.length = int(np.ceil(rdr_grid_original.length / dec_factor_az))
    interval_az = (rdr_grid_original.length - 1) / (rdr_grid_decimated.length - 1)

    rdr_grid_decimated.range_pixel_spacing *= interval_rng
    rdr_grid_decimated.prf /= interval_az

    return rdr_grid_decimated

rdr_grid_to_file(ref_grid_path, rdr_grid)

save parameters needed to create a new radar grid object

Source code in src/compass/utils/radar_grid.py 
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def rdr_grid_to_file(ref_grid_path: str,
                     rdr_grid: isce3.product.RadarGridParameters) -> None:
    '''save parameters needed to create a new radar grid object'''
    with open(ref_grid_path, "w") as f_rdr_grid:
        f_rdr_grid.write(str(rdr_grid.sensing_start) + '\n')
        f_rdr_grid.write(str(rdr_grid.wavelength) + '\n')
        f_rdr_grid.write(str(rdr_grid.prf) + '\n')
        f_rdr_grid.write(str(rdr_grid.starting_range) + '\n')
        f_rdr_grid.write(str(rdr_grid.range_pixel_spacing) + '\n')
        f_rdr_grid.write(str(rdr_grid.length) + '\n')
        f_rdr_grid.write(str(rdr_grid.width) + '\n')
        f_rdr_grid.write(str(rdr_grid.ref_epoch) + '\n')