This is normal, isometrics - rotate by 45 degrees, and the vertical compression twice. Additionally interferes with a surface defect.
If we take a monochromatic texture such as yellow, we see the band on the map brightness. It also distorts the texture, even if we made it seampless (no tiling).Added (25/July/2013, 7:46 PM)
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That's what I meant. The top texture - monophonic fill. On the map are streaks and spots. And the bottom texture - white color, but the results are so different.