I am changing a small part of the default coastline and I am using the technique of making a poly around a Qmid12 area, excluding all terrain from this (Poly1), inside this I make another poly (2) but still larger than the Qmid12 block. I then trace out the coast line overlapping poly2 I then make poly 2 generic ocean, then I slice all the polys to Qmid 12 (see another thread in this forum "Changing a small piece of the Alaskan coastline". My problem is this, all of the above works fine, almost all of the time but occasionally one or sometimes two adjacent Qmid blocks are solid land, I have checked at large zoom whether any of the poly's are over lapping but they are not. I have run out of ideas. Can anyone throw some light on this?
Cheers Norry.