estimate_gridding_opts#

emg3d.meshes.estimate_gridding_opts(gridding_opts, model, survey, input_sc2=None)[source]#

Estimate parameters for automatic gridding.

Automatically determines the required gridding options from the provided model, and survey, if they are not provided in gridding_opts.

The dict gridding_opts can contain any input parameter taken by emg3d.meshes.construct_mesh, see the corresponding documentation for more details with regards to the possibilities.

Different keys of gridding_opts are treated differently:

  • The following parameters are estimated from the model if not provided:

    • properties: lowest conductivity / highest resistivity in the outermost layer in a given direction. This is usually air in x/y and positive z. Note: This is very conservative. If you go into deeper water you could provide less conservative values.

    • mapping: taken from model.

  • The following parameters are estimated from the survey if not provided:

    • frequency: average (on log10-scale) of all frequencies.

    • center: center of all sources.

    • domain: from distance or vector, if provided, or

      • in x/y-directions: extent of sources and receivers plus 10% on each side, ensuring ratio of 3.

      • in z-direction: extent of sources and receivers, ensuring ratio of 2 to horizontal dimension; 1/10 tenth up, 9/10 down.

      The ratio means that it is enforced that the survey dimension in x or y-direction is not smaller than a third of the survey dimension in the other direction. If not, the smaller dimension is expanded symmetrically. Similarly in the vertical direction, which must be at least half the dimension of the maximum horizontal dimension or 5 km, whatever is smaller. Otherwise it is expanded in a ratio of 9 parts downwards, one part upwards.

  • The following parameter is taken from the grid if provided as a string:

    • vector: This is the only real “difference” to the inputs of emg3d.meshes.construct_mesh. The normal input is accepted, but it can also be a string containing any combination of 'x', 'y', and 'z'. All directions contained in this string are then taken from the provided grid. E.g., if gridding_opts['vector']='xz' it will take the x- and z-directed vectors from the grid.

  • The following parameters are simply passed along if they are provided, nothing is done otherwise:

    • vector

    • distance

    • stretching

    • seasurface

    • cell_numbers

    • lambda_factor

    • lambda_from_center

    • max_buffer

    • min_width_limits

    • min_width_pps

    • verb

Parameters:
gridding_optsdict

Containing input parameters to provide to emg3d.meshes.construct_mesh. See the corresponding documentation and the explanations above.

modelModel

The model; a emg3d.models.Model instance.

surveySurvey

The survey; a emg3d.surveys.Survey instance.

input_sc2int, default: None

If emg3d.models.expand_grid_model was used, input_sc2 corresponds to the original grid.shape_cells[2]. NOTE: Will be removed in v1.9.0.

Returns:
gridding_optsdict

Dict to provide to emg3d.meshes.construct_mesh.

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