Cincinnati Benchmarks - Open Data

In surveying, a benchmark - or bench mark or survey benchmark - is a post or other permanent mark established at a known elevation that is used as the basis for measuring the elevation of other topographical points. Updated quarterly.在测量学领域，水准基点（benchmark，亦称bench mark或测量基准点）是设置于已知高程处的标桩或其他永久性标记，可作为测算其他地形点高程的基准依据。该数据集每季度更新一次。