| description:
|
This dataset contains 3D rooftops for the District of Columbia in ESRI multipatch format. It includes structures originally captured from 2005 aerial imagery together with updates based on 2010 aerial imagery. It was produced under contract to the District of Columbia by CyberCity3D, Inc. using stereo imagery and a proprietary extraction process that identifies roof polygon points and then creates entire structures from them to form roof polygons.Attributes containing roof height, slope and orientation are included. This dataset is an update to a previous 3D dataset produced in 2006 using 2005 imagery. It specifically includes updates to building rooftops identified in the course of the District of Columbia’s separate planimetric update effort, which noted structures known that were added, modified between or deleted between 2008 and 2010. Although it was intended to capture all new buildings irrespective of whether or not they were identified through the planimetric update process, it is likely that building rooftop changes not identified through the planimetric update process may not have been captured. This dataset contains full rooftops, including protrusions such as gabled windows, chimneys, elevator utility rooms, etc.. There were also additional datasets delivered which broke out those roof elements into separate files, as well as deliveries which included complete 3D buildings with rooftops and facades. In many instances, row-houses and other contiguous building rooftops could not be broken apart using the process methodology and appear as a single structure. In some cases, entire blocks of row houses are represented as a single feature, though visually they can be distinguished easily. Additionally, the process captured small features, such as canopy umbrellas and other structures as building rooftops and these features may exist at various locations in the dataset.Many data gaps in the earlier dataset (largely due to missing or reduced-resolution source imagery) are corrected in this product. Based on comparison to DC’s available planimetric datasets, there are still instances where particular structures are omitted or not updated in the current product, but we believe that upwards of 99% of the District’s buildings are reflected in this dataset.All DC GIS data is stored and exported in Maryland State Plane coordinates NAD 83 meters. |