Due to the nature of the flags in this game, it's easy for the vision sensor to get confused with things that are behind the net. Red and blue are common colors on t-shirts, logos on walls, and on various school mascots that may wander behind the net.
For teams to use a vision sensor properly, would it be acceptable to hold up some sort of sheet behind the field to avoid this interference? Will the fields at Worlds be set up to mitigate background interference?
Due to the nature of the flags in this game, it's easy for the vision sensor to get confused with things that are behind the net. Red and blue are common colors on t-shirts, logos on walls, and on various school mascots that may wander behind the net.
In addition to their red and blue graphics, the Flags also include green graphics; this design was specifically chosen to reduce the impact of these types of "distractions".
It is typically outside of the scope of this Q&A to provide specific technical advice. However, in this case, we would like to point out that not only does this green strip give Robots something else to look for (instead of just red or blue), the V5 Vision Sensor also has the capability to identify two-color pairs, so that Robots can target a "red-green" or "blue-green" pair.
For teams to use a vision sensor properly, would it be acceptable to hold up some sort of sheet behind the field to avoid this interference?
There are no rules in the Game Manual explicitly prohibiting this (other than <G7>, if you are proposing to have a Drive Team Member holding up this sheet).
If you are proposing to put up this sheet permanently for an event, any proposed venue modifications must be discussed with your Event Partner. While it is not explicitly prohibited, it is also not a requirement; the final decision will need to be made at the Event Partner's discretion.
Because of this, we would advise teams to utilize the engineering design process and investigate programming solutions that mitigate the impact of undesirable conditions.
Will the fields at Worlds be set up to mitigate background interference?
Any information regarding field modifications specific to VEX Worlds will be released as part of the scheduled April 5th, 2019 Game Manual update.