There are three static strings in the interface of mitkSlicedGeometry3D :

static const std::string SLICES;
const static std::string DIRECTION_VECTOR;
const static std::string EVENLY_SPACED;

These variables are never set, and a search in the MITK source trees shows no usage of these variables. Additionally, they don't seem to have any purpose.

I found these code while creating a SWIG-based wrapping as they cause a linker error. I found out this is because they are never initialized. Therefore, i suggest to remove them.