<SG9> Robots may not enter (i.e. break the plane) of any Goal. Minor violations of this rule that do
not affect the match will result in a warning. Egregious (match affecting) offenses will result in
a Disqualification. Teams that receive multiple warnings may also receive a Disqualification at the
head referee’s discretion.
Would the plane of the low goal be the field-side of the PVC pipe or the inner goal side of the pipe?
Neither. Let’s take a look at the definition of the Low Goal.
Thus the plane in question is the plane that is perpendicular to the outer (closer to the center of the field) edge of the white tape line under the pipe. Since this will be hard to see in cases like the one you’ve shown, our referees will be instructed to be very lenient here and give teams the benefit of the doubt.