The interesting thing is that in real life the texture does not get smaller as it gets more distand, it only looks smaller. If you render a terain that is only say 30 in acros you would not expect their to be any change. If the object was larger Hundreds of feet you would expect to see the pattern getting smaller. Have you tried scalling the image UP (say by 1000%)so that you terain is larger and further across? I dont know if switching to meters or miles would mak any difference. I will give it a try later today.