Evaluating angles in soccer footage

I need to outline checks for assessing kicking angles, like the best spot for the "kick point," ensuring camera calibration aligns with pitch lines, and considering line thickness and camera parallax. Misalignment might occur if the wrong camera geometry is used. I can suggest validating with freeze-frames and knowing which body parts count during a play. I’ll offer a method to draw line checks for alignment, but recordings aren't needed if we don't have network restrictions.Discussing refereeing protocols

I want to point out that refereeing protocol states that decisions should only be made if they're "clear and obvious." However, offsides are factual measurements based on player edges. Some leagues, like the Premier League, have introduced thicker lines to favor attackers since 2021. I’m curious about Serie A's approach. Additionally, the technology used varies among leagues, with SAOT relying on multiple cameras for tracking. It’s essential to remember that broadcast lines can be misleading visual aids.Analyzing offside errors

One notable instance is the offside call in the "Luis Diaz" case against Spurs, which resulted from communication issues rather than a line error. Similarly, the 2020 match between Sheffield United and Aston Villa faced a goal-line technology failure, not a VAR line issue. There can be problems due to missing camera angles, like in the Juventus vs. Salernitana match, where a defender off-screen kept an attacker onside. I wonder if they want a breakdown of the laws or a frame-by-frame analysis?Proposing image analysis

I’m offering to analyze an image if the user can upload one. If they share the match details or time, we might be able to do a search, but I think it’s best to avoid going online unless necessary. I want to propose a concise explanation with bullet points highlighting potential VAR line problems and how to check these yourself. I could also explain how offside body parts are defined: anything except arms/hands, like knees and feet. Let's make it simple and clear!Cautioning about video analysis

I need to be careful here: without actually seeing the clip, I can't make a proper judgment. Different competitions use semi-automated offside technology (SAOT), and I should mention that Serie A began using it in the 2023/24 season. To avoid providing any incorrect information, I'll say that "some leagues/events are already using semi-automated offsides." It's a good way to clarify without diving into specifics that I can't verify.

看法一致：这种“划线看着不对”的争议常见。先给你一个快速框架，帮你判断问题可能出在哪，以及如何自查。

可能出的问题

• 触球瞬间选帧不准：应以出球者第一次触球的接触帧为准，提前/滞后一帧都会改变越位结论。
• 身体部位判定错位：越位只看可合法触球的部位（不含手臂/手）。肩部的有效边界常被误判成上臂。
• 线的几何校准误差：广播画面的辅助线可能没严格按3D标定来画，和场地线条不平行/不共消失点，看起来就“歪”。
• 镜头/帧率限制：低帧率或远景镜头，球与肢体的微小先后顺序很难精确锁定。
• 视差与镜头畸变：边线附近、广角镜头会带来透视畸变，肉眼以草坪条纹判断容易被误导。
• 画面不全：若有防守队员离镜头较远甚至出画，辅助线基准选错，结论会被拉偏。（历史上出现过缺少机位导致错判的例子）
• 制度差异：有的赛事用半自动越位（SAOT，3D肢体追踪），有的仍用2D划线，稳定性与容错不同。

你可以这样快速自查一帧截图

• 锁定“出球的第一接触”帧：逐帧看出球者的脚/球开始接触的瞬间，避免用球完全离脚的帧。
• 确认有效身体部位：进攻者与倒数第二名防守者，各找“最靠近球门线”的有效部位边缘点。
• 用场地线校验几何：把你画的基准线与禁区线/小禁区线比较，看是否严格平行；不平行说明该辅助线几何不可信。
• 检查重叠/遮挡：若关键部位被挡住，任何结论都高度不确定，需要其他机位。

一些背景点

• 裁判团队用的是经标定的系统，电视台的“演示线”只是可视化，不一定与VAR用的几何完全一致。
• 有的联赛采用“厚线/容差”给进攻方好处；SAOT则基于3D模型，误差主要来自选帧与肢体点定位，而非地面透视。

如果你愿意

• 发一张关键帧截图（尽量清晰、能看到出球瞬间和最近防守者），我帮你按上面步骤逐点标注分析。
• 或告诉我比赛/时间点（联赛、日期、上半/下半第几分钟），我给你复盘要点和最可能的技术原因。