Been having a look at the Rashford offside, because it didn't look right. Yes, I understand about perspective in principle, but it still looked a little distorted.
So hear me out.
What I did was take the image someone posted on here, and extended the relevant lines beyond the frame to see what happens. And whilst the way the grass is cut, and the halfway line is marked, gives straight lines across the pitch, the offside line is bent inwards at the centre of the pitch. Have a look at the below image with a line drawn across the pitch from where the offside line crosses both touchlines (you may need to enlarge it). There is a clear bend in the line, which isn't there for the grass lines. It looks like a few inches.
Not saying this is done deliberately, rather to suggest that we are accepting what happens with these lines without anyone independently appraising it. And when we do what we can to review it, the mm offside calls look a little suspect.
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Does anyone actually know how they are drawing these lines? If they are drawing them just from the images the broadcasters give them, the same images we see, how do they correct for perspective and parallax, when they don't have half the data points necessary to identify the correct angles (any more than we do). This is a complicated business and I would really like to hear how they are able to do this with the degree of accuracy they are claiming.
