Hi Degeus,
if you want "improved" photoscenery you should consider using an utility like FsEarthTile.
This program connects on a server, it downloads photorealistic tilemaps and then you can generate realistic terrains with appropriate terrain meshes.
The drawback of this, it takes a lot of time to generate tilemaps.
I don't know if it works with Prepar3d.
This utility is suitable for FSX