在全球变化研究和持续发展战略推动下形成的地理信息科学是数字地球的科学技术基础，而数字地球也为地理信息科学的发展提供了源动力。数字地球将深刻改变人类的政治、经济和科技格局。现在还不能给数字地球一个明确的定义，但可以认为数字地球的核心是一个分布式、多尺度、多维的地理信息系统。TGIS研究是实现数字地球的关键技术之一。目前可以本着综合型和分解型两种思路对TGIS进行平行探索。

The Digital Earth(DE) is based on Geographical Information Science (GISci), which is formed by the promotion of research into Global Change (GC) and Sustainable Development (SD) strategy. On the other hand, DE will accelerate the development of GISci. DE will deeply affect human society’s pattern of politics, economic, science and technology. It is difficult to give a clear definition of DE at present. But the core of DE should be recognized as a distributed, multi scale and 4 5 dimension GIS. TGIS is a key technology for implementing DE. At the moment, TGIS model can be researched according to two thoughts of comprehensive and decomposed model. Finally, TDBDML, a TGIS prototype based on decomposed thought, is described in detail.