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.exe’ to forward model and invert FDEM data. The manual for the original E3D v1 package (which uses ‘e3d.exe’) can be found here .

3. Elements of the E3DRH version 1 package

This section provides a brief description of each program in the E3DRH version 1 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 1 program library are:

• create_octree_mesh_e3d: creates an OcTree mesh based on the survey geometry

• e3drh: used to forward model or invert FEM data

The following Octree utility programs may also be helpful:

• blk3cell: creates conductivity models on the underlying tensor mesh

• 3DModel2Octree: interpolates models from tensor to OcTree meshes

• create_weight_file: creates the weighting on each cell in the model

• interface_weights: creates weights on the faces of cells

3.2. Main Input Files

Here, we describe the main input files for executables contained with the E3DRH version 1 coding 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 executable files. The input files for each executable program are described in the running the programs section.

• 3.3.1. Survey and Locations File
• 3.3.2. Predicted Data File
• 3.3.3. Observations File
• 3.3.4. Topography File
• 3.3.5. Tensor Mesh File
• 3.3.6. OcTree Mesh File
• 3.3.7. Model File
• 3.3.8. Model and Face Weights Files