Global Terrain, brilliant, but low res grid

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I'm new to this forum so hello everyone!

Just started to use the global terrain offered on the simviation web site - brilliant. However i was flying around Caracus in Venezuela (reference SA12 and SA10) (don't ask why) when i noticed that the scenery went from high res or loads of land detail to virtually none as you would normally get with FS 2004.

I had a look on the map and when zoomed in to a point where you can see the runway detail, sure enough there seemed to be an area not covered by the high res mesh on further research I noticed that there seems to be what looks like a grid of low res mesh that covers all of the areas I