How does VAR actually decide an offside call?

[Scarlett89]

Semi automated offside technology works by tracking specific skeletal points on every player on the pitch using multiple dedicated cameras positioned around the stadium, typically around 29 or more, all recording at extremely high frame rates. Combined with a sensor inside the match ball itself that detects the exact moment of contact when a pass gets kicked, the system can pinpoint precisely which frame the ball actually left the passer's foot.

At that exact frame, the system draws a virtual line based on the specific defending player's tracked body position, and compares it directly against the attacking player's tracked position at that same identical instant. If any part of the attacker's body that is legally allowed to score, generally excluding hands and arms, is beyond that defensive line at the moment the ball was actually played, the system flags the position as offside.

This is a genuinely meaningful upgrade from the earlier manual VAR process. Where a human official had to painstakingly draw those same lines by hand using video replay, a process that was noticeably slower and introduced real potential for small human error in exactly where those lines actually got drawn on screen.

The system does not actually make the final call entirely by itself though. It generates the specific positional data and a recommended decision, but a human video assistant referee still reviews that data and the actual match officials on the pitch make the final official call, the technology functions specifically as a genuinely precise measurement tool assisting human judgment rather than as a fully independent automated decision maker.

So the actual speed improvement fans notice mainly comes from automating the tedious and error prone process of measuring exact player positions. Not from removing human officiating from the equation entirely, a real person is still very much involved in confirming and delivering every single final call

[StringTheory97]

TLDR, cameras and a ball sensor track exact player positions at the precise moment the ball is played. The system draws virtual lines and flags likely offside positions automatically, but a human official still confirms the actual final call

[ProperWolf]

The ball sensor detecting the exact contact moment is the detail most fans do not realize even exists.

That specific piece of the puzzle is exactly what makes pinning down the correct precise frame possible in the first place

[Linda52]

Fans still argue plenty about marginal toenail offside calls even with this system in place. Worth remembering that precision measurement does not automatically make a quite close call feel any less controversial to the losing side

[Maverick50]

Nice breakdown!

Always assumed this whole process was basically fully automated with zero human involvement at all, particularly did not realize an actual official still confirms every single call before it goes final. Never really thought about it that way before

[Abbie92]

Does the system account for a player's actual playing stance somehow. Or does it just track a fairly simple skeletal outline regardless of exactly how someone happens to be positioned at that moment?

[Gold Terry]

Quick recap, cameras plus a smart ball sensor measure exact positions at the exact right moment.

Generate a recommended call automatically, and a human official still confirms it before it becomes official

[CollapseState75]

Bet the 29 plus camera setup alone costs an absolute fortune. Makes sense this specific technology is currently limited to major top tier competitions rather than being used everywhere across every single league

[Steady Dylan]

This explains why the new graphics look so much slicker and faster now compared to the old manual replay lines.

That automated skeletal tracking is doing clearly serious real time computational heavy lifting behind the scenes

[GoldDriver]

Wonder how this specific system actually handles a chaotic goalmouth scramble with a dozen players all clustered together.

Seems like that would be a much harder tracking scenario than a clean simple through ball