yep as ello put it above. rememeber both skins ahve to be power of 2 sizes, and both skins cannot be the same size ( typicaly the 2nd skin is smaller)

the first skin turn mipmap off, the second skin ( details skin) turn mipmap on

then in script adjust the detail_size value ( defualt is 4) > the value the more pixels are mapping


(same terrain detail size set to 2 in top image set to 9 in bottem image)


(note: detail_size is removed from manul because its suppost to be replaced by shaders, but it still working as of 6.4 but not for much longer in the later updates)