The Roadmap - Guidance on How to Build a Country’s Geospatial Reference System - Version 0.2 - 23 May 2025

Sep 1, 2026

The Roadmap defines how countries can modernise and implement a Geospatial Reference System (GRS) to align geospatial information from maps, satellite imagery and GNSS technologies to a unified national reference. It explains the purpose of a strong GRS in supporting precise positioning, smart infrastructure and resilience to climate and natural disasters, while enabling integration with international geodetic frameworks. It outlines the elements of a GRS—datums, transformation methods, standards and GNSS CORS infrastructure—and clarifies the practical applications and consequences of lacking a GRS aligned to ITRF.

LanguageEnglish

CategoryPresentations

FormatDOCX

Pages24

Reading Time8 min

AccessFree to download

Introduction

Purpose of this document

What is a Geospatial Reference System?

The Roadmap Guidance on how to build a country’s Geospatial Reference System Version 0.2 23 May 2025 About the UN-GGCE At its tenth session in August 2020, the United Nations Committee of Experts on Global Geospatial Information Management (UN-GGIM), in making decision 10/104, welcomed and supported an offer by Germany to establish and host what has now become the United Nations Global Geodetic Centre of Excellence (UN-GGCE) at the UN Campus in Bonn, Germany. The UN-GGCE, established in March 2023, is envisioned to be a federated centre and welcomes offers of support from Member States, including financial contributions, in person secondments, and virtual secondment. For more information about the UN-GGCE please visit: HYPERLINK "https://ggim.un.org/UNGGCE/" https://ggim.un.org/UNGGCE/ Document in development This is a preliminary version of The Roadmap based on the information available to the UN-GGCE as of April 7, 2025. Further information will be gathered throughout 2025 as the UN-GGCE implements capacity development training sessions. Updates to The Roadmap will be made available throughout 2025 and a final version will be made available in all UN languages in early 2026. Feedback and comments Your feedback and comments on this report are welcome. Please contact: Nicholas Brown, UN-GGCE Head of Office, E-mail: HYPERLINK "mailto:nicholas.brown@un.org" nicholas.brown@un.org Content TOC \o "1-3" \h \z \u HYPERLINK \l "_Toc195648696" Introduction PAGEREF _Toc195648696 \h 4 HYPERLINK \l "_Toc195648700" 1 Understand the current Geospatial Reference System and needs of stakeholders PAGEREF _Toc195648700 \h 7 HYPERLINK \l "_Toc195648701" 2 Communicate why an update to the Geospatial Reference System is needed PAGEREF _Toc195648701 \h 8 HYPERLINK \l "_Toc195648702" 3 Establish good governance PAGEREF _Toc195648702 \h 9 HYPERLINK \l "_Toc195648703" 4 Develop business cases PAGEREF _Toc195648703 \h 9 HYPERLINK \l "_Toc195648704" 5 Create a project plan PAGEREF _Toc195648704 \h 10 HYPERLINK \l "_Toc195648705" 6 Establish a GNSS network PAGEREF _Toc195648705 \h 10 HYPERLINK \l "_Toc195648706" 7 Collect GNSS data PAGEREF _Toc195648706 \h 11 HYPERLINK \l "_Toc195648707" 8 Process GNSS data PAGEREF _Toc195648707 \h 11 HYPERLINK \l "_Toc195648708" 9 Perform national geodetic adjustment PAGEREF _Toc195648708 \h 12 HYPERLINK \l "_Toc195648709" 10 Develop 7-parameter transformation PAGEREF _Toc195648709 \h 13 HYPERLINK \l "_Toc195648710" 11 Develop plate motion, distortion or deformation model PAGEREF _Toc195648710 \h 14 HYPERLINK \l "_Toc195648711" 12 Developing a physical height datum PAGEREF _Toc195648711 \h 15 HYPERLINK \l "_Toc195648712" 13 Update legal and policy documents PAGEREF _Toc195648712 \h 16 HYPERLINK \l "_Toc195648713" Appendix A: Geodesy Factbook PAGEREF _Toc195648713 \h 18 HYPERLINK \l "_Toc195648714" Appendix B: Communications Plan (Example) PAGEREF _Toc195648714 \h 19 HYPERLINK \l "_Toc195648731" Appendix C: Airborne Gravity Business Case Example PAGEREF _Toc195648731 \h 22 Introduction Purpose of this document The United Nations Global Geodetic Centre of Excellence (UN-GGCE) vision is a future where all countries have strong political support for geodesy which enables them to – together – implement the General Assembly Resolution 69/266 and accelerate the achievements of the Sustainable Development Goals to derive social, environmental and economic benefits. Key to a country achieving their goals is an accurate and reliable Geospatial Reference System which enables them to align and combine geospatial information and make better decisions. The Roadmap provides a guidance on how to modernise and implement a country’s GRS to ensure that all geospatial data—whether from maps, satellite imagery, or GNSS-enabled technologies—is accurately aligned to a unified, nationall

FAQs

What is the main purpose of the Roadmap?

It provides guidance to modernise and implement a country’s Geospatial Reference System so geospatial data is accurately aligned to a unified national approach.

Which components are included in a Geospatial Reference System (GRS)?

A GRS includes datums or reference frames, transformation and conversion methods, positioning standards, and infrastructure such as a national GNSS CORS network and survey marks.

How does a national GRS aligned to ITRF affect countries?

It improves consistency and reliability of geospatial data, enabling evidence-based decisions and policies, while supporting accurate positioning and integration with international geodetic frameworks.

Sep 1, 2026

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