ITS tomograms are produced using linear back projection (LBP) algorithms. These provide a good balance between fast calculations, spatial resolution and reproducibility.
The ITS Tomography Toolsuite has two further options to the standard LBP package.
The first is modified standard back projection (MSBP) which extends the operating range of the standard package. A characteristic of many reconstruction schemes which utilise a reference measurement is that reconstructed images taken from process conditions significantly away from the reference conditions are likely to have reconstruction artefacts. The MBSP algorithm extends the measurement range of data which can be reconstructed.
Capacitance tomography data can also be extended using the HDR (high dielectric reconstruction) which enables data taken with processes containing high dielectric materials (primarily water) to be analysed and reconstructed.
In addition to the above extensions to linear back projection, ITS also provides iterative reconstruction schemes. These generally are more mathematically robust methods and can produce more accurate reconstructions. However they need to be used with care as they can sometimes amplify the effect of process noise and also force boundaries between different regions in the process. The latter feature is very helpful where such boundaries exist (such as liquid gas interfaces in stratified flow regimes), however are less useful in the process exhibits a concentration gradient.
In the case of ERT data ITS offers algorithms based on the sensitivity conjugate gradient (SCG) method and has recently developed Landwebber based algorithm for ECT data sets.
Overall, ITS offers users a selection of tools for analysing tomography data along with technical support to advise users on the most appropriate for their application.