DC2DTree - 2D Impedance Tomography on Trees

Online documentation

Thomas Günther and Carsten Rücker (RESISTIVITY.NET),
version 0.9.1 (25.05.07), see release notes

Short description

The software enables the reconstruction of resistivity on cylinder geometry (trees, borehole cores, subsoil probes) from impedance measurements. Any combination of current/potential electrodes may be used.

Unlike other software, it incorporates the tree geometry by the use of unstructured trangle meshes and finite element modeling.

For a deeper insight see the following pdf (german version), which describes the numerical foundations and options (examples).

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Basically the inversion involves three steps (available by buttons):
  1. Create New Project (New Project Button): After reading a data file, a project directory is created where all information is stored. The .pro File contains the key information and can be loaded later via Load Project.
  2. Preparing the inversion (Prepare Button): Creation of the meshes, calculation of primary potentials and the initial sensitivity distribution. This step is numerically intense, but only called once and thus saves computing time. In case of a circle geometry these can be calculated analytically and the step may be omitted.
  3. Running the inversion (Run Button) does exactly what it means. The inversion is carried out in an external program using the given options. Due to the Prepare button the run-time is quite low so that different options can be tested quickly.

Inversion Options

The most important option is the regularization strength. It determines the smoothness of the resistivity distribution and can be adjusted with a slider.
Big values (100-1000) correspond to smooth solution, whereas small values (1-10) tend to show more structures. The Preview Button helps to try out the models of different complexity. Finally, the data should be fitted well (chi^2=1-10) without unnessecary structures. An automatic checkbox turns on autodetection. However this is not guaranteed to work.

Bad data may not be fitted well due to outliers. The robust inversion helps to find a better model through reweigting badly fitted data.

Often, a smoothed image of the reality is reproduced due to the errors. The Blocky model switch enforces sharp boundaries in the model.

Display and export

Different characteristics may be displayed (if available):
  1. Model (resistivity distribution or phase model)
  2. Data (apparent resistivities and phases)
  3. Model response, Compare data shows data, response and misfit
  4. Topo effect shows how the tree shape affects the apparent resistivities

Further possibilities

IP data may be inverted by a one-step method. Take care of the quality of the phase values (single outliers may spoil the results). With the blocky option the resistivity structure is involved into the constraints.

Mesh Options rarely needs a change. Sometimes the triangulation methods fails and can be fixed by slightly different values.


  • Data of other than dipole-dipole type may be displayed wrongly.
  • In case of few electrodes or coupling problems artifacts may arise at the boundary. However, they are restricted to the first few centimeters


There is no warranty for the program, to the extent permitted by applicable law. The author is not liable for any damages or costs resulting from its use.


Download any version of and execute the installer. Note that the versions > 0.9 do not need the libraries in system.exe anymore.
The software operates on Windows XP/2000/Me, may also work on older systems.


Although a pure academic and non-commercial use is free, a license file is needed to provide full facilities. It is hardware-dependent and can easily be obtained by calling Start->Programs->Generate License Code and sending the code with your information to thomas@resistivity.net.

see also the pages for DCGEO, DC2DInvRes and DC3DInvRes