Import FEM data

To import frequency-domain electromagnetic (FEM) data, use the main project menu:

ImportDataFrequency-domain EM

There are four types of FEM data that can be loaded from files:


File formats: EM1DFM format

Loads a data file for the EM1DFM inversion and forward modeling codes. The data position is set relative to the transmitter as specified by the EM1DFM file format. The function returns a FEM1Dsounding object.

ImportDataFrequency-domain EMGIF EM1D format

The following parameters are set for the user:


  • Transmitters:
    • Dipole moment: mom_t

    • Orientation ot_a

    • Along-line offset (m) = 0

    • Cross-line offset (m) = 0

    • Vertical offset (m): Relative to topography

  • Receiver:
    • Dipole moment: mom_r

    • Along-line offset: The along-line position of receivers, relative to transmitter locations

    • Cross-line offset: The cross-line position of receivers, relative to transmitter locations

    • Vertical offset: Relative to topography


The position of the data is set by the “sounding” location. Only the relative offsets between the transmitters and receivers are available in the EM1DFM file format. Data locations have been assigned to the transmitter locations upon import for consistency. E3D format

Loads data files formated for the original E3D data file format . The function returns an FEMdata object where only the transmitter geometry is defined. The receivers are defined as point measurements that samples the fields (E, H) along the Cartesian axes.

ImportDataFrequency-domain EMGIF E3D format


The FEMdata object assumes that the provided field data have been measured along the Cartesian axes or that the user has rotated the fields in pre-processing. For more general cases with arbitrary receivers orientation (in-line), consider making use of the FEM3Dsounding class. E3D v2 format

Loads data specifically formatted for the E3D v2 and E3D v2 tiled codes. The function returns an FEM3Dsounding object.

ImportDataFrequency-domain EMGIF E3D v2 format


The receivers and transmitters are defined by their respective input files. As a result, you will need 4 files when importing E3D v2 data:


Both the transmitters and receivers geometry are defined in 3D. The relative offsets can be calculated using the Calculate Transmitter/Receiver separation function.