The unified data format

All projects in our working group use a unified format such that data are transpararent and transportable. There are a lot of import and export filters for third party software or hardware, but internally the following structure is used. Since the most applications use multi-electrode systems they are based on the way they are addressed (and computed in modeling).

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 places after the # character. After the number of data the definition for each datum is 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 position for each electrode
0     0
1     0
2     0 # loose ground
3     0
4     0
5     0
6# Number of data
1   2   3   4  231.2
2   3   4   5  256.7
3   4   5   6  312.8
1   2   4   5  12.1 # possibly an outlier
2   3   5   6  199.7
1   2   5   6  246.2

If other fields or order are used, a token string in the line after the data number specifies the given fields. The token may be followed by a slash and a physical unit. The following tokens are allowed (case insensitive).

Tokens	Meaning	possible units
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 Ra	apparent resistivity	Ohmmeter
rho R	Resistance	Ohm
err	Error	1(default),%,Ohm
ip	IP measure	mRad(default),°,FE,MF
I	Current	A(default),mA,uA
U	Voltage	V(default),mV,uV

The following sample contains voltages, currents and a percentage error.

...
6# Number of data
# a b m n U I/mA err/% for each datum
  1   2   3   4  -0.5305165 102.2 2.4
  2   3   4   5  -0.5305165 99.9  1.4
  3   4   5   6  -0.5305165 95.6  2.6
  1   2   4   5  -0.1326291 100.1 7.6
  2   3   5   6  -0.1326291 80.2 8.6
  1   2   5   6  -0.05305165 77.3 7.5

...
  1   2   5   6  -0.05305165  7.5
4# Number of topo points
# x h for each topo point
0 353.2
12 357.1
19 359.9
24.5 350

Buried/borehole electrodes

Spectral IP data