AarhusInv Settings

The AarhusInv settings are written to the configuration file used by AarhusInv when running the inversion.

The list represent the most frequently changed settings for the used data type, but even so most users will have no need to change any of these settings.

Clicking on a key or value change the description below to show the key, the range of allowed values for that key and a short description of what the key does.

The descriptions below go through the most frequently changed settings.

Depth of investiation (DOI) related settings:

  • DOI: This controls whether the DOI is calculated or not.
  • DOINLayers: This sets the number of layers in the DOI calculation which controls the discretization intervals of the DOI calculation. More intervals will increase the computation time, while fewer intervals will decrease the accuracy of the DOI calculation. The final DOI values are found by interpolation between the layers.
  • DOIDepth1: This sets the minimum depth of the discretization intervals which should reflect the ideal resolution capabilities of the used system/method.
  • DOIDepthN: This sets the maximum depth of the discretization intervals which should reflect at least the maximum depth of investigation by the used system/method.

Data space and constraint reference related settings:

  • LogData: This controls whether to invert in logarithmic (log) og linear (lin) data values. The default it to use logarithmic data values, but it cannot be used if there are negative data values.
  • DepthRef: This controls whether to use depth or elevation as reference for lateral constaints. Depth-referenced lateral constraints will favor layers following topography while elevation-referenced lateral constraints will favor horizontal layers.
  • AltRef: This controls whether to use height (above ground) or elevation as reference for altitude constraints. This should be set based on the used system. Helicopter based systems try to fly at a constant height above ground while faster airplane based system fly at a constant elevation (above water level).

Inversion related settings:

  • NIteAlt: Number of iterations before introducing the altitude as a parameter in the inversion. When inverting airborne data the altitude is usually included as an inversion parameter. Since the inversion can be very sensitive to altitude however, it is often beneficial to first invert a number of iterations with only the model resistivities and depths before including the altitude in the inversion.
  • NIteAng: Number of iterations before introducing pitch and roll as parameters in the inversion. The same as the similar setting for altitudes and only relevant when inverting for pitch and roll.
  • NIteTau: Number of iterations before introducing tau as parameters in the inversion. The same as the similar setting for altitudes and only relevant when inverting for tau.
  • NIteC: Number of iterations before introducing C as paramter in the inversion. The same as the similar setting for altitude and only relevant when invertion for C.
  • NApproxDeriv: Number of iterations inverted with approximate TEM response derivatives. The default is 50 and when combined with the next setting, there is usually no reason not to use that. Approximate responses can however not be used when inverting airborne TEM IP, so there it needs to be set to 0.
  • EndFull. When set this cause the inversion to switch to exact derivatives when it would otherwise have stopped. It will then continue the inversion using the exact deriveatives.
  • MaxStep: This controls the maximum allowed parameter change at the 1st iteration. Allowing larger steps can cause the inversion to reach a solution faster, but it can also cause the inversion to get stuck with a less than optimal solution. Only allowing smaller steps can cause the inversion to improve so slowly that it stops the inversion too early. This is for experts only.
  • CalcAnalysis: This controls whether the analysis will be calculated or not.
  • PartypeDamping: This changes how the parameter damping is done in the inversion. In the past the same damping was used for all parameters, but for IP inversion it is often useful to use individual damping for each parameter type.


Any changes to the values will be stored in the registry and used for later inversion of that same data type, but by pressing the Default Values button all settings will be returned to default values for that data type. This include AarhusInv settings that are not otherwise on the user interface but may have been changed in the registry earlier.

For already created Spatially Constrained Inversion nodes, the values will be read from the configuration file that was created along with the inversion node ignoring the registry. The values on this user interface can still be changed, but the Default Values button has been disabled.

Expert user can request a custom made file from support that will allow them to change any AarhusInv settings that they might need through this user interface, even settings that haven’t otherwise been added to Aarhus Workbench.