Libre Map Project

Abstract: The development of linked data on the World-Wide Web provides the opportunity for the U.S. Geological Survey USGS to supply its extensive volumes of geospatial data, information, and knowledge in a machine interpretable form and reach users and applications that heretofore have been unavailable. To pilot a process to take advantage of this opportunity, the USGS is developing an ontology for The National Map and converting selected data from nine research test areas to a Semantic Web format to support machine processing and linked data access. In a case study, the USGS has developed initial methods for legacy vector and raster formatted geometry, attributes, and spatial relationships to be accessed in a linked data environment maintaining the capability to generate graphic or image output from semantic queries. The description of an initial USGS approach to developing ontology, linked data, and initial query capability from The National Map databases is presented.

Abstract: With the approaching completion of the U.S. Geological Survey's l:24,OOO-scale mapping program for the conterminous United States, map revision becomes a primary activity. Experimental techniques for ~ap revISion are being developed which require digitizing both map and photographic sources in a raster format, reCtlfymg the resulting data to a common coordinate system, simultaneously displaying the digital map and photographic data, performmg visual change detection, and manually updating the digital map data with an on-screen digitizing procedure. Updated image and line map output are generated from the raster data using a film-write device. Map revision performed completely in the raster domain achieves geometric accuracies sufficient to meet National Map Accuracy Standards at the 1:24,000 scale from 7 m pixel data and 1:100,000 scale from 28.5 m pixel data. Approximately 80 percent of the transportation and hydrography features are updated at the 1:24,000 scale from the 7 m pixel raster data.