Urban Historical Boundaries, 1850

Urban area boundaries for 1850, part of the Baltimore-Washington Spatial Dynamics and Human Impacts dataset. The Baltimore-Washington Spatial Dynamics and Human Impacts dataset is an integrated and flexible temporal urban land characteristics database for the Baltimore-Washington metropolitan area. The compilation of this data is a collaborative effort led by the U.S. Geological Survey and the University of Maryland Baltimore County. The database provides visual and historical perspective of the urban growth experienced in the area between 1792 and 1992. Data on built-up areas exists as separate geographic layers for the dates: 1792, 1801, 1822, 1850, 1878, 1900, 1925, 1938, 1953, 1966, 1972, 1982, and 1992. Temporal urban mapping reconstructs past landscapes by incorporating historic maps, census statistics, and commerce records to generate a progressive geo-referenced picture of the past changes in a region. Contemporary mapping focuses on the use of remotely sensed data, existing digital land use data, digital census information, and a variety of earth science infrastructure data, such as Digital Line Graphs, Digital Elevation Models, and key ancillary demographic information. Different procedures were used for different time periods, more fully described for each file in the Process Step Section 2.5.2. The resulting database of temporal urban land use/land cover and demographic changes provides an ideal source of test data and information for both urban geographers and global change research scientists. While this dataset was developed by the University of Maryland Baltimore County final quality control and metadata generation was performed by the University of Vermont's Spatial Analysis Lab. Two significant problems were noted regarding this dataset. The first anomoly is that the 1801, 1822, and 1878 layers have a much smaller extent, and contain data only for Baltimore City. The second discrepancy is that there are also some very obvious positional errors causing misalignments between layers of different dates (i.e. urban areas become non-urban in a very short time period, an unlikely occurance). This is part of a collection of 221 Baltimore Ecosystem Study metadata records that point to a geodatabase. The geodatabase is available online and is considerably large. Upon request, and under certain arrangements, it can be shipped on media, such as a usb hard drive. The geodatabase is roughly 51.4 Gb in size, consisting of 4,914 files in 160 folders. Although this metadata record and the others like it are not rich with attributes, it is nonetheless made available because the data that it represents could be indeed useful. This is part of a collection of 221 Baltimore Ecosystem Study metadata records that point to a geodatabase. The geodatabase is available online and is considerably large. Upon request, and under certain arrangements, it can be shipped on media, such as a usb hard drive. The geodatabase is roughly 51.4 Gb in size, consisting of 4,914 files in 160 folders. Although this metadata record and the others like it are not rich with attributes, it is nonetheless made available because the data that it represents could be indeed useful.

1850年城市区域边界数据，属于巴尔的摩-华盛顿空间动态与人类影响（Baltimore-Washington Spatial Dynamics and Human Impacts）数据集。巴尔的摩-华盛顿空间动态与人类影响数据集是面向巴尔的摩-华盛顿大都市区的集成化、可灵活复用的时态城市土地特征数据库。本数据集的汇编工作由美国地质调查局（U.S. Geological Survey）与马里兰大学巴尔的摩分校（University of Maryland Baltimore County）牵头的合作团队完成。该数据库可直观展现该区域1792年至1992年间的城市扩张历程与历史变迁。建成区数据按年份划分为独立的地理图层，对应年份分别为：1792、1801、1822、1850、1878、1900、1925、1938、1953、1966、1972、1982及1992年。
时态城市制图通过整合历史地图、人口普查统计数据与商业记录，重构区域过去的景观演变，生成具有地理参考坐标的区域历史变迁时序图谱。现代城市制图则依托遥感数据、现有数字土地利用数据、数字人口普查信息，以及各类地球科学基础设施数据，例如数字线图（Digital Line Graphs）、数字高程模型（Digital Elevation Models）与关键辅助人口统计信息。针对不同历史时期采用了差异化的处理流程，各文件的详细处理步骤参见2.5.2节处理步骤部分。
最终生成的时态城市土地利用/土地覆盖与人口变化数据库，可为城市地理学家与全球变化研究学者提供优质的测试数据与研究参考资料。本数据集由马里兰大学巴尔的摩分校开发，最终的质量控制与元数据（metadata）生成工作由佛蒙特大学空间分析实验室（University of Vermont's Spatial Analysis Lab）完成。
该数据集存在两处明显问题：其一，1801年、1822年与1878年的地理图层覆盖范围显著更小，仅包含巴尔的摩市的数据；其二，存在较为明显的位置偏移误差，导致不同时期的图层出现对齐偏差（例如，城市用地在极短时间内转变为非城市用地，这一情况不符合现实逻辑）。
本数据集属于指向某一地理数据库（geodatabase）的221条巴尔的摩生态系统研究（Baltimore Ecosystem Study）元数据记录之一。该地理数据库体量庞大，可在线获取。若符合特定条件并提出申请，也可通过USB硬盘等存储介质寄送。该地理数据库总容量约为51.4吉字节（Gb），包含160个文件夹下的4914个文件。尽管本条元数据记录与其他同类记录的属性信息不够丰富，但鉴于其所代表的数据具备较高的实用价值，仍予以公开共享。
本数据集属于指向某一地理数据库（geodatabase）的221条巴尔的摩生态系统研究（Baltimore Ecosystem Study）元数据记录之一。该地理数据库体量庞大，可在线获取。若符合特定条件并提出申请，也可通过USB硬盘等存储介质寄送。该地理数据库总容量约为51.4吉字节（Gb），包含160个文件夹下的4914个文件。尽管本条元数据记录与其他同类记录的属性信息不够丰富，但鉴于其所代表的数据具备较高的实用价值，仍予以公开共享。