The successful development of domain applications often requires a tremendous volume and a wide variety of data from different agencies and organizations. Location-enabled information add a brand new spatial viewpoint for determining the best strategies to resolve real world problems. Unfortunately, domain users normally have limited or even no knowledge about how the available geospatial data is collected or produced. As a result, the data selected for specific applications may contain all kinds of uncertainty and inconsistency that may endanger the quality of the decisions. SDI offers an obvious advantage for making the sharing of georesources easier, but the correct integration of data from different resources certainly demands a more comprehensive approach to enable the cross-domain data exchange and interactions on a common and reliable spatial reference basis.

Topographic maps have long been recognized as an effective medium for presenting spatial phenomena in reality. Users nowadays widely use web-based map service based on the contents of topographic maps to learn the environments and make decisions. In addition to this traditional reference map approach, we argue topographic maps have the ability to play a more active and aggressive role in serving spatial reference and linking domain data to facilitate interoperable cross-domain applications in SDI. Maintained by professional surveying agencies, government-owned topographic maps are special products that have both nation-coverage and abundant variety of themes of data with fixed data quality. Furthermore, the positional accuracy and abstracted location of individual features are also examined and ensured following rigorous surveying specifications. This implies features extracted from topographic maps are excellent sources for sharing with other agencies, provided their related information can be well described and appropriate mechanism for bridging  to other domains can be developed. We propose a self-described feature approach in this paper, where the design of distributed topographic features consists of well-formed information about the unique identifier, theme code, time, core thematic attributes, data quality and links to the technical specifications adopted. Distributed on the basis of individual features, agencies from other domains can thus easily add or link their domain-specific information to the distributed topographic features in an interoperable fashion. This can effectively reduce the duplicated cost for creating data and in the meantime improve the consistency when integrating data from different domains because their spatial references originally come from a common basis. As topographic maps are updated with a fixed time frequency, this approach further adds temporal aspects to the shared data and avoid wrong uses of data.

In Taiwan, the government agencies are collaboratively working under the umbrella of NGIS. Being one of the nine major spatial databases, the “Basic Topographic Database” is responsible for providing different types of topographic products for other agencies’ operation reference. The feature-level description framework not only makes the resource sharing and later applications more flexible and powerful, but also has potential to facilitate the innovated developments of open data and attract more users to use topographic data in the future.