I've got a situation where I need to make a large area of terrain, with some areas at higher detail/resolution than others. I have three heightmaps, one covering, say, a 10x10km area, one covering a 1x1km area and the final covering a 100x100m area, all of the smaller areas are embedded in the larger one, giving a high resolution coverage of the chosen area while still providing coverage for the larger, outer areas too.
So my question is: How do I (preferably in Blender) create a terrain which combines these three 'levels of detail'? Of course I tried just applying the heightmaps as displace modifiers to 3 different planes and putting them one on top of the other, but it didn't look great! Is there a way to apply the three different heightmaps to the same plane with each one acting on its own small area?