Blender-osm plugin now supports terrain import.

Blender-osm is an addon for Blender. It provides one click download and import of OpenStreetMap and terrain data with global coverage.

The following items can be imported by the addon:

• Buildings. Building height and number of floors are used to create the final scene. Composition into 3D parts for a building with the complex structure is also processed. A large number of roof shapes is supported: flat, gabled, hipped (for a quadrangle outline only), mono-pitched, half-hipped, round, pyramidal, gambrel, dome, onion and saltbox. If a terrain is provided, buildings are placed on the terrain automatically.
• Water objects (rivers and lakes). Imported as polygons. Coastlines for seas and oceans are importes as edges. If a terrain is provided, polygons for water objects are projected on the terrain.
• Vegetation areas (forests, grass, scrubs). Imported as polygons. If a terrain is provided, polygons for vegetation areas are projected on the terrain.
• Highways, paths and railways. Imported as edges.
• Terrain. blender-osm downloads and imports real world terrain data with global coverage and the resolution about 30 meter. More information.
• Polygons with holes are supported

Addon costs $5.90. You can get it here.