roadrunner wrote:My personal view:
Something like "middle feature" when there are more than 3 in the circle would be complicated - the description itself is easy enough to understand but not so easy to see on the map.
if you see "middle" in the description it probably means there are more than 3.
Unless the 3 features are virtually in a straight line it will be better to describe which way the correct feature is offest from the other 2.
The eye is quite sensitive to things being central and uncrossable features (on the map) are thick lines (0.4mm minimum) - so I would have thought that a very small offset would suffice. Have a look at this (yes, I know the colours are wrong, I don't have a recent version of OCAD with the sprint colours); the top circle is centred on the side of the "uncrossable feature", the bottom one 0.4mm further offset. I can't instantly tell which side the top one is centred but the bottom one is very clear, so that suggests that it doesn't need much of an offset. At 1:4000, 0.4mm on the map is 1.6m on the ground, so I don't think that's significant in terms of the flag not being at the centre of the circle. Of course, it might not be as clear if the uncrossable feature wasn't straight
I'm really not sure this offsetting business is a good idea. And certainly not to the extent of going so far that the centre of the circle is not even touching the mapped feature. The issue is not whether the circle is exactly at the location of the kite, but that centre of the circle identifies the feature (which may itself be offset from its true location on the map) in the description.
Yes, it is easy to see from your uncluttered and extremely enlarged example, with only one straight line bisecting the circle that it is out by a little bit one side or the other. But real control sites tend to be a lot busier than that, probably with cuts in the circle and other features interfering. Indeed you should be wary of using a control site on a straight stretch of a linear feature as it is only defined in one dimension unless there are surrounding features to nail the location.
If there were multiple uncrossable features you introduce ambiguity about which feature the control is to the side of - try your lower example with another hedge at the minimum separation running parallel.
One approach that can work is to offset the circle, but then to describe the feature that actually is at the centre of the circle. For example if the area to the west was paved and the area to the east a lawn then you could use "open land western part".