Each circle-sphere containment is mapped into an incidence between a point and a semicircle.
One young man stepped from the semicircle and motioned towards the one with the camera.
Here parent trees had most likely died and left spaces in the centres of the semicircles of what are now their offspring.
Another young man in the wider semicircle wore a baseball hat.
Clearly, these semicircles form a collection of pseudo-segments, that is, each pair of them intersects at most once.
He looked at the semicircle, including the four people on chairs.
A radial line from the center of the semicircle to a given target location indicates intact orienting at that target location.
We recorded birds which appeared within a semicircle with a radius of 25 m from the fixed point.
