recently i compiled OpenCV 4.5.3 with VTK 9.0.20210919 on Windows.

i was sure that i already compiled and installed VTK flawlessly but at first try running cmake i get "VTK is not found. Please set -DVTK_DIR in CMake to VTK build directory, or to VTK install subdirectory with VTKConfig.cmake file" message.

after an investigating i changed this line as if(VTK_VERSION VERSION_GREATER "9") # VTK 9.0 and solved the problem.

maybe it is not a general or right solution but i hope this info will be useful.