Determining line of sight vs cover

[Nikosandros]

It would seem that the best thing is simply to ignore the part in the DMG about the four lines blocked from every corner. We can just use the PHB ruling that you need LOE in order to target the square.

 

[deleteme123456]

The problem with "guessing" a square is that they want to argue "my non-blinded allies tell me '10 feet in front of you and 20 feet to the left'"... and that seems... well, on the one hand, I admire the teamwork, but on the other hand, it seems like it's defeating the purpose of blinding the wizard at all. Maybe I could have the wizard roll 1d10, on a 0 or 9 you hit the correct square, else you're off by 1 in the direction indicated starting from the top of the map / north (whichever is better defined at the moment) and continuing clockwise) to simulate the guesswork involved in measuring distances with your eyes closed.

 

[Majoru Oakheart]

Thought this might help clear a few things up.

Doesn't number one in that picture only have cover since two lines still touch corners of the enemies square? Since lines that pass along the side of an obstacle like that count as "visible"?

 

[Kordeth]

Doesn't number one in that picture only have cover since two lines still touch corners of the enemies square? Since lines that pass along the side of an obstacle like that count as "visible"?

Assuming you mean PC #1 in the big illustration at the bottom, no. You're confusing cover with line of sight. A line that touches an obstacle blocks line of sight.