"GT" wrote in message
...
Recently, I needed to measure a distance in the garden, of roughly 30
feet, which I know can be done adequately with a simple tape measure,
to withing an inch or so.

But then I got to thinking....purely out of curiosity, what would be
the MOST accurate way to measure distances of say 20 to 50 feet,
outside, on uneven land. Or for that matter, between any two points !

I expect to hear all about sonic measuring devices, tape measures
pulled very tight etc. etc., but what i'm really trying to discover is
who can come up with the MOST ACCURATE, regardless of cost.

Then, the MOST ACCURATE, at the least cost.

Over that distance: a tape measure in both cases.
One by putting it through a ridged tube to keep it straight.

Unless you are talking about building a temperature controlled room and
using an interferometer to measure differences of a few wavelengths of light
that is.