Though millions of geo-service layers exist just a click away, there is no good way to discover most of them. In the early days of the web it was hard to find a web page; this situation holds today for most geo-data.
With a grant from the National Endowment for the Humanities, the CGA is building a platform to create, maintain, and deploy a global public registry of web map services, and has developed a new visual interface to support searches by time and space. The technology can scale to millions, even billions of objects.
The CHGIS project has produced a comprehensive series of datasets related to the administrative geography of Chinese History. The data layers include nationwide coverages (for the years 1820 and 1911), and time series (for the Dynastic period from 221 BCE to 1911 CE). The administrative features include Provinces, Circuits, Prefectures, and Counties as they changed over time. Supplemental datasets include G.W. Skinner regional systems, Buddhist sites, features from historic Russian maps of China, Tibetan townships, modern gazetteer layers for each province, and many others.
Writer Paul Salopek is walking the path of human migration from Africa to the tip of South America, and writing stories along the way, as part of a 7 year journalism project. The CGA is making maps for Paul as he travels this route.
Map 1: Shows exposed sea beds at the human migration started, and the rough path humans took.
Map 2: uses Fuller projection and spectral coloring scheme to illustrate distance traveled and time required for humans to travel this path.
Map 3: Thematic map of elevation to illustrate the undulating nature of the first leg of the walk.