I understand that once the center of a circle is established, a rope can be used to walk a given arc about the center. Once two ends of a line are know, a rope can be used to define the line. Those procedures are used in ordinary surveying work using tape measures ("chains") instead of ropes. The relative location of the reference points (centers and endpoints) to each other is main problem. I agree that crop circles do not have to bear any relation to existing features such as the roads, fences, pipes etc. that are part of the design of driveways and roads. The designs do have certain symmetries and this imposes some constraints on them.

If I think of laying out crop circles as complicated, at least I'm doing it from the perspective of having done surveying field work myself. I haven't heard a convincing explanation yet about why making crop circles is so simple. I understand that there could be situations where the design is a spontaneous artistic creation. This could happen if the workers can be directed from some vantage point that can see the design. I understand that with a low crop, the reference points could be set using an ordinary surveying transit since you have line-of-sight to places that you want to drive a stake. However, thinking about how I would do it in a tall crop and without some direction from an observer, I would use modern equipment like a GPS unit and a programmable calculator. Store the reference points in some coordinate system and when you get to the field, convert the coordinates to the location that you select.

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