This format is used in all "model" files defining a conductivity or chargeability model. That is, starting models, reference models, final models in either the DC resistivity or IP forward modelling or inversion have the same structure. Each file contains the cell values of the model. The number of cells in the x and z directions are specified in this file but the lengths and widths of cells are defined in fdmesh.dat.
The extension `.con' identifies a conductivity model and `.chg'
identifies a chargeability model. Although these extensions are not
mandatory for input files, the inversion programs attach such extensions
to the final model. The file structure for model.con or model.chg is as follows:
The model is stored in a row format with V1,1 being the top left cell.
Each row of the model,
In the presence of topography, the cells above the surface specified by topo.dat represent the air and, therefore, are not part of the model. For simplicity, however, the files model.con and model.chg must include those cells as defined by the file fdmesh.dat. These cells in the model file will be ignored when the model is input to a program. To distinguish these cells, the user can assign a special value to them, for instance, a very small value (say 10-10) for conductivity and a negative value for the chargeability model. These cells in the output model files from the inversion programs have a conductivity value equal to 10-8 times the mean conductivity value immediately beneath the surface and a chargeability value of -1030.