Not really sure what you mean with "the real place". Also would be nice to know which engine. For Unreal 4 I would recommend checking out the documentation here, there is almost everything you need to know for importing a heightmap: https://docs.unrealengine.com/latest/INT/Engine/Landscape/TechnicalGuide/
You can resize your heightmap in Photoshop or other software to any of these sizes listen in the link below. (Look for Overall Size column) https://docs.unrealengine.com/latest/INT/Engine/Landscape/TechnicalGuide/index.html#recommendedlandscapesizes Then when you import your heightmap in UE4 it'll create a landscape of…