Electrical Methods Survey File
The input survey file provides the locations of electrodes and describes how electrodes are used to produce measurements.
In inverse run modes, the input survey file also lists measurement values and standard deviations.
An output survey file with the extension of <.srv> is created during Forward Modeling
that is named after the conductivity file used in the forward simulation. The simulated measurements are entered in place of the observed measurements.
This file is meant to aid synthetic imaging studies, whereby simulated data collected within a known conductivity distribution are used to investigate aspects
of the inversion. The standard deviation of each measurement is entered as 5% of the transfer resistance magnitude as a placeholder,
but noise is not added to the simulated data.
See File Syntax Rules for specific details.
| Variable Name | Description |
|---|---|
| n_elec
(int) |
n_elec is the number of electrodes. |
| e_ind ex ey ez e_flag
(int) (real) (real) (real) (int) |
e_ind is the electrode number. ex, ey and ez are the coordinate positions of the electrode. e_flag is the boundary flag for the electrode. e_flag = 0electrode is below the surface e_flag = 1electrode is on the surface e_flag = negative integerNegative values are used to specify infinite conductivity boundaries (e.g. metallic) and must also be included in the mesh. One electrode must be specified for each boundary (e.g. each negative node boundary number in the mesh). In this case, e_flag is the boundary number on which the electrode lies. *Negative flag values can only be used with installation of the IMI module |
| n_meas
(int) |
n_elec is the number of measurements. |
| m_ind a b m n v_obs v_std
(int) (int) (int) (int) (int) (real) (real) |
m_ind is the measurement number. a is the electrode index of the positive current electrode. b is the electrode index of the negative current electrode. m is the electrode index of the positive potential electrode. n is the electrode index of the negative potential electrode. v_obs is the observed transfer resistance*. v_std is the standard deviation of v_obs*. *For forward modeling, v_obs and v_std are not used, however a value must be entered. |
repeat for n_elecForward ERT Simulation Modeling Example
48 number of electrodes 1 -7.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 1 2 -6.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 2 3 -5.5 -5 0 1 e_ind, x, y, z, ... 2070 number of measurements 1 1 2 3 4 10.0 1.0 m_ind a b m n v_obs v_std 2 1 2 4 5 10.0 1.0 note: the v_obs and v_std are arbitrary placeholders in this example ...
Forward ERT Simulation Modeling Example with IMI module
51 number of electrodes 1 -7.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 1 2 -6.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 2 3 -5.5 -5 0 1 e_ind, x, y, z, ... 49 -4.0 -1.0 -1.0 -1 control point on box (#61 in mode_ERT1/metal_box_sheet_line/mbsl.cfg) 50 4.0 -1.0 -1.0 -2 control point on sheet (#69 in in mode_ERT1/metal_box_sheet_line/mbsl.cfg) 51 0.0 0.0 -0.25 -3 control point on line (#125 in mode_ERT1/metal_box_sheet_line/in mbsl.cfg) 2070 number of measurements 1 1 2 3 4 10 1 m_ind a b m n v_obs v_std 2 1 2 4 5 10 1 note: the v_obs and v_std are arbitrary placeholders in this example 3 1 2 5 6 10 1 ...
Forward ERT Modeling Output Example
48 number of electrodes 1 -7.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 1 2 -6.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 2 3 -5.5 -5 0 1 e_ind, x, y, z, ... 2070 number of measurements 1 1 2 3 4 -26.5258 1.32629 m_ind a b m n v_obs v_std 2 1 2 4 5 -6.63145 0.331573 note: simulated measurement values, v_std=0.05*|v_obs| 3 1 2 5 6 -2.65258 0.132629 ...
Inverse ERT Modeling Input Example
48 number of electrodes 1 -7.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 1 2 -6.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 2 3 -5.5 -5 0 1 e_ind, x, y, z, ... 2070 number of measurements 1 1 2 3 4 -26.5258 0.530516 m_ind a b m n v_obs v_std 2 1 2 4 5 -6.63145 0.132629 note: v_std is determined from field data errors, in this case 0.02*|v_obs| was used 3 1 2 5 6 -2.65258 0.053051 ...
| Variable Name | Description |
|---|---|
| n_elec
(int) |
n_elec is the number of electrodes. |
| e_ind ex ey ez e_flag
(int) (real) (real) (real) (int) |
e_ind is the electrode number. ex, ey and ez are the coordinate positions of the electrode. e_flag is the boundary flag for the electrode. e_flag = 0electrode is below the surface e_flag = 1electrode is on the surface e_flag = negative integerNegative values are used to specify infinite conductivity boundaries (e.g. metallic) and must also be included in the mesh. One electrode must be specified for each boundary (e.g. each negative node boundary number in the mesh). In this case, e_flag is the boundary number on which the electrode lies. *Negative flag values can only be used with installation of the IMI module |
| n_meas
(int) |
n_elec is the number of measurements. |
| m_ind a b m n v_obs v_std i_obs i_std
(int) (int) (int) (int) (int) (real) (real) (real) (real) |
m_ind is the measurement number. a is the electrode index of the positive current electrode. b is the electrode index of the negative current electrode. m is the electrode index of the positive potential electrode. n is the electrode index of the negative potential electrode. v_obs is the observed transfer resistance*. v_std is the standard deviation of v_obs*. i_obs is the observed phase*. i_std is the standard deviation of i_obs*. *For forward modeling, v_obs, v_std, i_obs, and i_std are not used, however a value must be entered. |
Forward SIP Modeling Example
48 number of electrodes 1 -7.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 1 2 -6.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 2 3 -5.5 -5 0 1 e_ind, x, y, z, ... 2070 number of measurements 1 1 2 3 4 10.0 1.0 10.0 1.0 m_ind a b m n v_obs v_std i_obs i_std 2 1 2 4 5 10.0 1.0 10.0 1.0 note: the v_obs, v_std, i_obs and i_std are arbitrary placeholders in this example ...
Inverse SIP Modeling Example with IMI module
51 number of electrodes 1 -7.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 1 2 -6.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 2 3 -5.5 -5 0 1 e_ind, x, y, z, ... 49 -4.0 -1.0 -1.0 -1 control point on box (#61 in mode_ERT1/metal_box_sheet_line/mbsl.cfg) 50 4.0 -1.0 -1.0 -2 control point on sheet (#69 in in mode_ERT1/metal_box_sheet_line/mbsl.cfg) 51 0.0 0.0 -0.25 -3 control point on line (#125 in mode_ERT1/metal_box_sheet_line/in mbsl.cfg) 2072 number of measurements 1 1 2 3 4 -26.012 1.3006 -0.99730E-01 0.49865E-02 m_ind a b m n v_obs v_std i_obs i_std 2 1 2 4 5 -6.5629 0.32814 -0.99785E-01 0.49893E-02 note: simulated measurement values 3 1 2 5 6 -2.6146 0.13073 -0.99561E-01 0.49780E-02 ...
Inverse SIP Modeling Example
48 number of electrodes 1 -7.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 1 2 -6.5 -5 0 1 e_ind, x, y, z, surface electrode values for electrode 2 3 -5.5 -5 0 1 e_ind, x, y, z, ... 2070 number of measurements 1 1 2 3 4 -17.901 0.89503 -0.99675E-01 0.49838E-02 m_ind a b m n v_obs v_std i_obs i_std 2 1 2 4 5 -3.9144 0.19572 -0.99684E-01 0.49842E-02 note: simulated measurement values ...