grid2grid¶

emg3d.maps.grid2grid(grid, values, new_grid, method='linear', extrapolate=True, log=False)[source]¶

Interpolate values located on grid to new_grid.

Note 1: The default method is ‘linear’, because it works with fields and model parameters. However, recommended are ‘volume’ for model parameters and ‘cubic’ for fields.

Note 2: For model parameters with method=’volume’ the result is quite different if you provide resistivity, conductivity, or the logarithm of any of the two. The recommended way is to provide the logarithm of resistivity or conductivity, in which case the output of one is indeed the inverse of the output of the other.

Parameters:

grid, new_grid : TensorMesh

Input and output model grids; TensorMesh instances.

values : ndarray

Model parameters; emg3d.fields.Field instance, or a particular field (e.g. field.fx). For fields the method cannot be ‘volume’.

method : {<’linear’>, ‘volume’, ‘cubic’}, optional

The method of interpolation to perform. The volume averaging method ensures that the total sum of the property stays constant.

Volume averaging is only implemented for model parameters, not for fields. The method ‘cubic’ requires at least three points in any direction, otherwise it will fall back to ‘linear’.

Default is ‘linear’, because it works with fields and model parameters. However, recommended are ‘volume’ for model parameters and ‘cubic’ for fields.

extrapolate : bool

If True, points on new_grid which are outside of grid are filled by the nearest value (if method='cubic') or by extrapolation (if method='linear'). If False, points outside are set to zero.

For method='volume' it always uses the nearest value for points outside of grid.

Default is True.

log : bool

If True, the interpolation is carried out on a log10-scale; hence the same as 10**grid2grid(grid, np.log10(values), ...). Default is False.

Returns:

new_values : ndarray: Values corresponding to new_grid.