Even though the third party module vtkjsoncpp is stripped by the ebuild, the vtkjsoncpp.cmake file is installed, causing missing vtkjsoncpp libarary errors by the linker of software using VTK.
And vtkjsoncpp is not the only one, as a $(ls /usr/lib/cmake/vtk-6.1/Modules) tells.
How does the error look like?
> How does the error look like?
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.3/../../../../x86_64-pc-linux-gnu/bin/ld: cannot find -lvtkjsoncpp
collect2: error: ld returned 1 exit status