Philadelphia Land Cover Raster 2008 2011

High resolution land cover dataset for Philadelphia. Seven land cover classes were mapped: (1) tree canopy, (2) grass/shrub, (3) bare earth, (4) water, (5) buildings, (6) roads, and (7) other paved surfaces. The minimum mapping unit for the delineation of features was set at ten square feet. The primary sources used to derive this land cover layer were 2008 Orthophotography and 2008 LiDAR LAS data. Ancillary data sources included GIS data (building footprints, road polygons, and hydrography) provided by City of Philadelphia. This land cover dataset is considered current as of 2008. Object-based image analysis techniques (OBIA) were employed to extract land cover information using the best available remotely sensed and vector GIS datasets. OBIA systems work by grouping pixels into meaningful objects based on their spectral and spatial properties, while taking into account boundaries imposed by existing vector datasets. Within the OBIA environment a rule-based expert system was designed to effectively mimic the process of manual image analysis by incorporating the elements of image interpretation (color/tone, texture, pattern, location, size, and shape) into the classification process. A series of morphological procedures were employed to insure that the end product is both accurate and cartographically pleasing. No accuracy assessment was conducted, but the dataset was subject to a thorough manual quality control. More than 30700 corrections were made to the classification.

This data is hosted at, and may be downloaded or accessed from PASDA, the Pennsylvania Spatial Data Access Geospatial Data Clearinghouse http://www.pasda.psu.edu/uci/DataSummary.aspx?dataset=138

费城高分辨率土地覆盖数据集。本次共划定7类土地覆盖类型：(1) 树冠层，(2) 草本/灌丛，(3) 裸露地表，(4) 水体，(5) 建(构)筑物，(6) 道路，(7) 其他铺装表面。地物勾画的最小制图单元设定为10平方英尺。本土地覆盖图层的核心数据源为2008年正射影像（Orthophotography）与2008年激光雷达LAS（LiDAR LAS）数据。辅助数据源包括费城市政府提供的GIS数据，涵盖建(构)筑物基底（building footprints）、道路多边形与水文矢量数据。本土地覆盖数据集的现势性截至2008年。
研究采用面向对象影像分析（Object-based image analysis, OBIA）技术，结合当前最优的遥感与矢量GIS数据集提取土地覆盖信息。OBIA系统基于像素的光谱与空间特征，将其聚类为具备语义信息的地物对象，同时兼顾现有矢量数据集划定的边界。在OBIA处理环境中，研发了一套规则型专家系统，通过将影像解译要素（色彩/色调、纹理、格局、位置、大小与形状）融入分类流程，有效模拟人工影像解译的完整过程。此外，通过一系列形态学处理流程，确保最终成果兼具分类精度与制图美观性。本数据集未开展专门的精度评估，但经过了全面的人工质量控制，累计完成超过30700处分类修正。
本数据托管于宾夕法尼亚空间数据访问地理空间数据交换中心（Pennsylvania Spatial Data Access Geospatial Data Clearinghouse, PASDA），可通过以下链接下载或访问：http://www.pasda.psu.edu/uci/DataSummary.aspx?dataset=138