I need to acquire a very detailed topographic map of Istanbul, Turkey without any markers. Do you know such sources who provides these kind of maps? I tried to Google it, but the results were far from satisfactory. I found world topography from NASA, some low resolution images that does not worth much. There are a lot for US but unfortunately I failed to find one for Istanbul.
Actually since I don't the details of GIS, I don't know the technical terms to explain what I am looking for. But here is what I'll use the map for: I am going to print 3D version of Istanbul using some 3D printer, and display visualizations on top of it using projector hooked on the ceiling. In this case, I assume that I need either a 3D point cloud, or a 2D height map where I can deduce 3D points after some processing.