Alien Panel Points?

These are two pictures. First one shows the actual brass cap monument designating a National Geodetic Control Point. These points are benchmarks used by surveyors to establish horizontal and vertical control for aerial photography and topography.

What's really bizarre with this point is Picture No. 2 which shows a “Panel Point.” Typically these points are made up of four 5' long paper “legs”. The intent of these legs is to make them visible to airplanes flying a site to generate topography for a development. This particular panel point is made up of concrete legs 20' in length.

Why it is so large and made up of concrete rather than paper is curious? We found two other points just like this one in our survey. Maybe for a very high altitude photo. Like in outer space.

National Geodetic Control Point
Brass cap monument designating a National Geodetic Control Point
panel point
Panel Point with 20 foot "legs."