Important

In the spring of 2022, a new suite of FDEM OcTree codes were compiled: E3DRH, E3DRH v2 and E3DRH v2 tiled. These codes use a right-handed coordinate system; as opposed to the modified left-handed coordinate system used by E3D, E3D v2 and E3D v2 tiled. You are currently viewing the manual for the package which uses ‘e3drh_v2.exe’ to forward model and invert FDEM data. The manual for the original E3D v2 package (which uses ‘e3d_v2.exe’) can be found here .

3. Elements of the Program

This section provides a brief description of each program in the E3DRH version 2 package. In addition, we describe the file formats for all input and supporting files used by the coding library.

3.1. Program Library

The main executable programs within the E3DRH version 2 program library are:

• e3drh_v2: single executable file for carrying out forward modeling and inversion of FEM data

• create_octree_mesh_e3d_v2: creates a the OcTree mesh based on transmitter and receiver locations

The following Octree utility programs may also be helpful:

• blk3cellOct: creates a conductivity model on the OcTree mesh

• create_weight_file: creates cell weighting for the recovered model

• interface_weights: creates weights on the faces of cells for the recovered model

3.2. Main Input Files

Here, we describe the main input files for executables contained with the E3DRH version 2 package.

• 3.2.1. Create octree mesh
• 3.2.2. Create octree model
• 3.2.3. Forward modeling
• 3.2.4. Create face weights
• 3.2.5. Inversion

3.3. Supporting Files

Here, we describe the formats of supporting files used to run e3drh_v2.exe. The input files for each executable program are described in the running the programs section.

• 3.3.1. Survey Index File
• 3.3.2. Observations File
• 3.3.3. Predicted Data File
• 3.3.4. Frequencies File
• 3.3.5. Transmitter/Receiver File
• 3.3.6. Topography/Polygon File
• 3.3.7. Tensor Mesh File
• 3.3.8. Octree Mesh File
• 3.3.9. Model File
• 3.3.10. Model and Face Weights Files