Can't build VTK sample project: Missing module

Regarding the source installation: I just checked the CMakeCache.txt in the build folder. I found this entry:

//The directory containing a CMake configuration file for VTK.
VTK_DIR:PATH=VTK_DIR-NOTFOUND

The directory I specified isn’t applied. Am I giving cmake the wrong directory? I just assumed (following the build directions) I had to point to “vtk/build”. The instructions say

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

…but this clearly failed