It's not required if you know CMake and know what you're doing. There's even resources, if you search for them, e.g.: https://github.com/gerkey/ros1_external_u

It's not required if you know CMake and know what you're doing. There's even resources, if you search for them, e.g.: https://github.com/gerkey/ros1_external_use https://github.com/gerkey/ros1_external_use But if you're looking for good documentation and tutorials, then yes catkin is basically required, but I don't think that's unreasonable.