I made two adjacent geoconvert sceneries of Sydney immediately touching each other (the latitude of the southern border of one is the same as that of northern border of the other. I have attached the coordinates below). There appears a thin black line in exactly the same location of the border. It is especially obvious below 1000 feet. This is not to be confused with the abnormal stripes we mentioned earlier, which can also be seen ahead of the black line in my pic attached.
I have to make a lot of adjacent regions and join them into a very large region because one large region will crash my computer. Now this thin black line makes this process more difficult. I will try making regions overlapping each other to see if can eliminate the black line.