Every data set consists of two mandatory parts: electrode definitions and arrangement
definition. Subsequently the number of electrodes, their positions (x z for 2D, x y z for 3D)
, the number of data and their definitions are given.
Comments may be placed after the # character.
After the number of data the definition for each datum can be given row-wise by the electrode numbers for the current electrodes A and B (C1 and C2) and the potential electrodes M and N (P1 and P2).
They may be followed by other attributes (see list below).
Standard is the apparent resistivity and optional the relative error as exemplified for a tiny dipole-dipole survey.
6 # Number of electrodes
# x z
2 0 # loose ground
6 # Number of data
#a b m n rhoa
1 4 2 3 231.2 # A Wenner point
1 2 3 4 231.2 # Dipol-dipole sequence
2 3 4 5 312.8
3 4 5 6 12.1 # possibly an outlier
1 2 4 5 256.7
1 0 5 6 199.7 # Pole-dipole
1 0 5 0 246.2 # Pole-pole
The token string in the line after the number of data can be omitted for the order A B M N rhoa (error).
Otherwise it is used to specify the given columns
The token may be followed by a slash and a physical unit.
The following tokens are allowed (case insensitive).
The following sample contains voltages, currents and a percentage error.
|a c1||electrode number for A (C1)|
|b c2||electrode number for B (C2)|
|m p1||electrode number for M (P1)|
|n p2||electrode number for N (P2)|
|rhoa rho_a Ra||apparent resistivity||Ohmmeter|
|R Z rho||Resistance/Impedance||Ohm|
|err error std||Error/standard deviation||1(default),%,Ohm|
6 # Number of data
# a b m n U I/mA err/%
1 2 3 4 -0.5305165 102.2 2.4
2 3 4 5 -0.5305165 99.9 1.4
1 2 4 5 -0.1326291 100.1 7.6
Topography may be given in two ways.
1. Each electrode can be given a height value as z position (preferred by webinv).
2. Alternatively, the data may be followed by a topo list (preferred by DC2dInvRes).
1 2 5 6 -0.05305165 7.5
4# Number of topo points
# x h for each topo point
Buried/borehole electrodes vs. topography
There might be confusion about using z for surface topography or buried/borehole electrodes,
(DCndInvRes understands z usually as depth, wheras DCTopo reads it as topography)
In order to distinguish between both we provide different tokens for the electrode list:
Besides x and y used for real coordinates, h (for height) and d (for depth below surface) can be provided.
So the definition is unique, furthermore it is possible to combine both. A z will still be interpreted problem-dependent.