A properly designed football field does not lie perfectly flat. Its middle portion is slightly raised to promote runoff of excess water. Without it, the field can become muddy & uncomfortable.
Some flat-Earthers conducted the perspective convergence ‘experiment’. They put a camera on the surface of a football field, and record a person walking away across the field. The person started to disappear from his feet first. Because they felt the football field is flat, they took the wrong conclusion that the person disappeared due to ‘perspective’. They were wrong. The field is, in fact, not perfectly flat. If it is perfectly flat, the person would appear fully at the end of the field.
References
- Drainage management – Cornell University
- Field Crowns & Surface Drainage – Ohio State University
- Turf vs. Grass – Soccer Politics
- What Is the Crown of a Football Field? – Sports Rec
- Quandaries and Queries – University of Regina
- Handbook of Requirements for Football Turf – FIFA
- The FA’s National Ground Grading documents – The FA
- Slope – Wikipedia