Need help with a sobel edge post process effect :(

i found the delta that was calculating the edge of the entire mesh, i messed it up a little bit to see how it works, and it seems that if i decrease the minus number that divides the current edge calculate before, i get this horrid shadow in the distance, but at least i found it 388ca4d3749f73263af0aea11715d88a4fb49523.jpeg