The grass grainer is an idea i stole from the flytampa folks, but they do it with a transparent mask of the photo layer letting the grainer come up through from behind.... I tried this but could not get enough contrast in the sat layer unless i hard contrasted the sat layer and it still didn't look right... the grainer texture i made looked nice, but it never looked right when i tried their technique... i just wasn't getting the mix right, and it was alot of work to mask the sat texture with a detiled alpha channel and still not get it to look good at all...
So what I did was put the satellite layer first, then layed the grainer over the top, using an alpha mask to let it 'texture' the smooth satellite layer below it. Very sloppy, but it kept the contrast and color of the sat ground texture, and detailed it with a grassy grain to give it some detail.... i cheated, it was easier to get it to look better...
What DOES happen, is it graines everything its above... not a problem for most things, it doesnt show through the slightly transparent taxiway textures, so there is no issue there, and the runways are fully textures, with no bleedthrough, so no problem there either...
I dont want to get into process here in the showroom, as these techniques should be outlined in the gmax rooms, and not here... there may be some techniques in the gmax room already to explain how to do this, it IS quite easy... its all in the way you prepare the grainer texture. and its alpha.
I appreciate your kind comments to my work, thank you