When a team either reviews to get a wicket or to over turn a wicket, there is umpires call for impact in line with the stumps and impact of the stumps.
When the ball is close to pitching in line with the stumps in DRS, why is it the case that there is no umpires call and is either pitching in line or outside leg stump.
Pitching position is determined by the actual ball on a flat surface. To the extent that an error exists, it consists of a pixel on a screen.
For the ball hitting the pads, it is not possible to reliably say from current camera angles the height at which the ball hit the pads, and therefore the error is large enough to be applied.
For the ball hitting the stumps, this is only available from computer modelling, and a fixed margin of error of half the ball's width is applied to the result.
