One of our more seasoned Canadian friends on here offered this tip a while back on a similar thread that i use as I find it works well for me. Imagine if you were driving along the highway and you look up ahead into the distance to the point where the broken white lines seem to merge together, that's how far, not just over the nose and not the runway end.
Yes some time ago I wrote a piece on how to judge height. I can't find it now and am to lazy to re write it.
Unless you can accurately judge how high your wheels are above the runway you can not make consistent good landings.
Where you are looking is what determines how accurately you can judge height.
Look to close and the runway is a blur.
Look to far ahead and the angle is to shallow to properly judge height.
The optimum distance ahead of the airplane that you focus is where apparent movement towards you ceases.....in a light bug smasher that is about 500 feet down the runway.