大地基準與框架之國際發展

International Developments in Geodetic Datums and Frames

大地基準（Geodetic Datum），是各國建立其測量製圖及空間資訊應用所依據之空間框架。在以三角測量為主要技術的年代，大地基準之全球連結主要仰賴天文測量加以實現。而今，包含特長基線干涉測量（Very-Long Baseline Interferometry，VLBI）、衛星雷射測距（Satellite Laser Ranging，SLR），與全球導航衛星系統（Global Navigation Satellite System，GNSS）等空間測地技術的整合，已為全球一體且高精度之空間參考架構，奠定了堅實的實現基礎。
當今國際上各國的大地基準，多已採用GNSS的連續運營參考站（Continuous Operating Reference Station，CORS）所構成之網系，並對齊特定曆元的國際地球參考框架（International Terrestrial Reference Frame，ITRF），作為國家大地基準之實現方法，臺灣大地基準（Taiwan Datum 1997，TWD97）亦屬此類架構。隨著板塊運動、地殼變形及地震等效應日益受到重視，大地基準由靜態模式逐步朝向可反映時變之動態模式發展。紐西蘭於1998年正式發佈並實施稱為New Zealand Geodetic Datum 2000（NZGD2000）半動態大地基準，即為此一轉型的重要里程碑，代表國家大地基準管理進入兼顧空間與時間變化的新階段。本文回顧美國、日本、歐盟、澳洲、紐西蘭的大地基準發展，分析其在基準框架維護、曆元更新及動態管理方面之作法，作為規劃新一代臺灣大地基準之重要參考。

Geodetic Datum serves as the fundamental spatial reference framework for national surveying, mapping, and geospatial information applications. During the era when triangulation was the primary surveying technique, the global connection of geodetic datums was mainly achieved through astronomical observations. With advances in geodetic technology, the integration of space geodetic technologies, such as Very-Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), and Global Navigation Satellite Systems (GNSS), has established a solid foundation for the realization of a globally unified and highly accurate spatial reference framework.
At present, most countries have adopted national geodetic datums based on networks of GNSS Continuous Operating Reference Stations (CORS), and aligned with the International Terrestrial Reference Frame (ITRF) at a specific reference epoch. Taiwan’s geodetic datum, TWD97, is also implemented under this framework. As tectonic plate motion, crustal deformation, and seismic activities have become increasingly significant, geodetic datums have gradually evolved from static models toward dynamic frameworks capable of reflecting temporal variations. In 1998, New Zealand officially released and implemented a semi-dynamic geodetic datum known as the New Zealand Geodetic Datum 2000 (NZGD2000), marking an important milestone in this transition, representing a new stage in national geodetic datum management that considers both spatial and temporal changes.. This paper reviews the geodetic datum developments in the United States, Japan, the European Union, Australia, and New Zealand, and analyzes the approaches to reference frame maintenance, epoch updates, and dynamic management. The findings are intended to provide important references for the planning and development of the next-generation geodetic datum in Taiwan.