SaLIS Vol. 66, No. 2, June 2006
ACSM - U.S. Report to the International Federation of Surveyors, Germany, October 2006

Preface by Wesley Parks, Guest Editor

This is a special issue of Surveying and Land Information Science, a scientific and technical journal of three member organizations of the American Congress on Surveying and Mapping—AAGS, GLIS, and NSPS—and one of the principal journals of surveying in the United States of America. The issue is special because it constitutes a Report to the Federation Internationale des Geometres (FIG; International Federation of Surveyors) on the current state of U.S. surveying practice. It is also special in that it contains papers describing specific surveying activities that members of three U.S. professional surveying societies consider representative of current U.S. surveying practice. Besides being a Report to FIG, the special issue is a report to the U.S. community of surveying and mapping professionals from these three professional societies.The focus of the Report is the basic land survey. When a U.S. surveyor is retained by a client to do a survey, he or she will probably begin by performing some sort of control survey. Further, almost all land surveys have some sort of boundary aspect, thus they are at least partially land surveys. Results of surveys increasingly include various items of information georeferenced to some sort of universal coordinate system. This information may very well be used ultimately in a geographic information system or land information system (GIS/LIS). Finally, regardless of what type of surveying one is engaged in, eventually one will need to confront questions regarding such basic concepts as location and elevation. Following this focus, the Report is organized into four main sections, with an additional introductory section. The main sections are Control Surveying, Land Surveying, Geographic Information Systems, and Basic Surveying Concepts. The introductory section presents the American Congress on Surveying and Mapping and its involvement with FIG. It begins with a paper on the state of U.S. surveying by John Fenn John Hohol, and Curt Sumner, which presents a historical perspective of ACSM and describes recent changes to its structure and the impact of these changes on the relationship between FIG and ACSM. Following this introduction, John Hohol introduces a new ACSM organization, the ACSM FIG Forum, and the 2006 U.S. delegation to FIG.The section on current U.S. control surveying activity begins with a paper by Wendy Lathrop and Daniel Martin of the past, present, and future role of the American Association for Geodetic Surveying (AAGS), the principal U.S. control surveying professional society. The authors highlight activities which AAGS believes are critical to the future of positioning in the U.S. and to those using the technology. United States government involvement in control surveying is discussed in a paper by Dru Smith and David Doyle which describes the future role of geodetic datums in control surveying in the U.S. The paper outlines 200 years of U.S. government efforts to define, maintain, and provide access to geodetic datums, based on a reliance on physical monuments. Its authors focus on new space geodetic techniques that allow the National Geodetic Survey to approach datum definition and control surveys in an entirely new way, a way that minimizes the need for passive survey marks in the ground. An example of U.S. private surveying company involvement in control surveying is provided in a paper by Willam Henning. He describes the private sector surveyor as poised to enter a new era of control surveying. Henning highlights the trend away from surveys using densely spaced permanent physical monumentation towards surveys utilizing more sparse physical networks and establishing site coordinates utilizing the Continuously Operating Reference Station (CORS) system as truth. The section on current U.S. land surveying begins with a paper by Robert Dahn and Rita Lumos on the activities, accomplishments, and goals of the National Society of Professional Surveyors (NSPS), the principal U.S. land surveying professional society. United States Government involvement in land surveying is discussed in a paper by Donald Buhler on Cadastral Survey activities in the U.S. The author notes that cadastral surveys are primarily a function of the more than 3000 county governments in the U.S. and that, with the exception of the original thirteen colonial states, most county cadastres are built upon a rectangular survey system maintained by the U.S. Bureau of Land Management. The section on current U.S. geographic information systems and science begins with a paper by Joshua Greenfeld on the activities of the Geographic and Land Information Society (GLIS), the principal U.S. control GIS/LIS professional society. According to Greenfeld, a major goal of GLIS has been to bridge the gap between traditional surveying and mapping professionals and the GIS community. He notes that the society was instrumental in bringing about the realization of the importance of surveying within the GIS community. Two perspectives of GIS/LIS education in the U.S. are presented in a paper by Gary Jeffress and Thomas Meyer, faculty members of Texas A&M University-Corpus Christi and the University of Connecticut, respectively. The Report’s consideration of basic concepts of surveying is presented in three of a series of four papers by Thomas Meyer, Daniel Roman, and David Zilkoski, in which the authors ask “what does height really mean?” The first paper reviews reference ellipsoids and mean sea level datums; the second focuses on the physics of heights, including the notion of the geoid, and explains why mean sea level stations are not all at the same orthometric height. Both of these papers have previously appeared in this Journal, in, respectively, vol. 64, no.4, December 2004, and vol.65, no.1, March 2005. The third paper develops the principle notions of height from measured, differentially deduced changes in elevation to orthometric heights, Helmert orthometric heights, normal orthometric heights, dynamic heights, and geopotential numbers. The fourth paper in this series will appear in a forthcoming issue of Surveying and Land Information Science.

The American Congress on Surveying and Mapping, Inc., and ACSM’s Involvement with FIG by John Fenn, John Hohol, and Curt Sumner

Recent changes to the governance structure of ACSM have resulted in some alterations in the character of ACSM’s relationship with FIG. This article provides a historical perspective about ACSM, describes the nature of the governance changes and their impact on the ACSM/FIG relationship, and explains that the mission of ACSM remains unchanged.

The ACSM FIG Forum and ACSM FIG Delegation by John Hohol, Head of Delegation

The American Association for Geodetic Surveying: Its Continuing Role in Shaping the Profession by Wendy Lathrop and Daniel Martin

The profession of surveying and positioning, and their related technologies and activities, are evolving at a staggering rate. Additionally, the tools and technology associated with positioning, once reserved for scientists and professional surveyors, are now widely available and utilized by many professional and non-professional disciplines. These disciplines can further be broken down into categories referred to as traditional and non-traditional users. This paper will discuss the past, present, and future role of the American Association for Geodetic Surveying (AAGS), highlighting activities which AAGS believes are critical to the future of positioning in the United States and to those using the technology.

The Future Role of Geodetic Datums in Control Surveying in the United States by Dru A. Smith and David R. Doyle

For nearly 200 years, the U.S. Government has been in the business of defining, maintaining, and providing access to geodetic datums. However, for all but the last 20 years, the definition and realization of those datums has been through very similar observational techniques using passive marks in the ground. The advent of space geodetic techniques has allowed the National Geodetic Survey to approach datum definition and control surveys in an entirely new way. A plan is being established which will allow future datums to be defined through 4-dimensional coordinates on continuously operating GNSS reference stations (CORS) and an accurate gravimetric geoid, thus effectively minimizing the need for passive survey marks in the ground.

The New RTK—Changing Techniques for GPS Surveying in the USA by William Henning

The private sector surveyor in America stands poised to enter a new era of control surveying. Traditional methods of Global Positioning System (GPS) static and single base Real Time Kinematic (RTK) control surveying found in most surveying and engineering shops, will soon give way to integrated networks of reference stations interpolating corrections for the point of survey rather than at the base station. Rather than using densely spaced “permanent” or passive physical monumentation, the trend is towards using surveying from much sparser physical networks and establishing site coordinates utilizing the Continuously Operating Reference Station (CORS) system as truth. However, even these newer approaches of post-processed static GPS surveying are yielding in many venues to the rosier cost-to-benefit ratio of using networked RTK.

National Society of Professional Surveyors by Robert E. Dahn and Rita Lumos

The activities, accomplishments, and on-going efforts and goals of the National Society of Professional Surveyors (NSPS) on behalf of the surveying community are reviewed. Ranging from government affairs to educational programs, a broad stroke overview of NSPS in 2005-2006 is provided.

Cadastral Survey Activities in the United States by Donald A. Buhler

The cadastral survey activities of the United States vary in scope and detail. Cadastral surveys are primarily a function of county governments; there are over 3000 counties in the United States. Most of the cadastral systems are built upon a rectangular survey system, with the exception of the metes and bounds systems in the states of the original thirteen colonial. The Bureau of Land Management has the responsibility for this rectangular survey system and facilitates the creation of a national cadastre.

The Geographic and Land Information Society and GIS/LIS Activities in the United States by Joshua S. Greenfeld

The Geographic and Land Information Society (GLIS) is the youngest and the smallest member organization of the American Congress on Surveying and Mapping (ACSM). The main goal of GLIS is to bridge the gap between traditional surveying and mapping professionals and the GIS community. In spite of its modest size, GLIS has had a considerable impact on both professional communities. The society was instrumental in bringing about the realization of the importance of surveying within the GIS community. The GIS community is becoming more aware of the importance of surveying to GIS, and of the importance of the surveyor’s participation in GIS activities. One example of this recognition was the inclusion of surveying activities (spatial data compilation) as GIS professional experience in the Urban and Regional Information Systems Association’s GIS certification criteria. The Geographic and Land Information Society is also making headway in making the surveying community more aware of the need to become involved in GIS, by promoting GIS activities in State Surveying Societies and by providing educational opportunities for surveyors at ACSM and other surveyors’ conferences.

Two Perspectives of GIS/LIS Education in the United States by Gary Jeffress and Thomas Meyer

Education in Geographic information science (GIS/LIS) happens in the United States both within surveying-related academic programs and in other academic programs that use spatially oriented data and information. This article presents an overview of two such programs. The first is a four-year Bachelor of Science degree program in Geographic Information Science at Texas A&M University-Corpus Christi. The second is a concentration with a four-year Bachelor of Science degree program in Natural Resources at the University of Connecticut (UConn). Geographic information science is the primary focus of the Texas A&M program, whereas GIS/LIS is an emphasis of the UConn program. Both approaches are presented for comparison.

Basic Surveying Concepts

In this section of the ACSM-U.S. Report to FIG, we present three papers of the “What Does ‘Height’ Really Mean? series by Thomas Meyer, Daniel Roman, and David Zilkoski, which provides the conceptual basis for projects aiming to improve resource management through the use of accurate height data. “Height modernization” projects have become a major focus of the work of several U.S. federal agencies in the past four years. The first two “Height” papers in the series have already been published in this Journal, as Part 1: Introduction [vol. 64, no. 4, pp. 223-233] and Part II: [vol. 65, no. 1, pp. 5-16]. Their reprinting in this issue is intended to provide a comprehensive background to the third paper in the series, Part III: Height Systems.

What does height really mean? Part I: Introduction by Thomas H. Meyer, Daniel R. Roman, David B. Zilkoski

This is the first paper in a four-part series considering the fundamental question, “what does the word height really mean?” National Geodetic Survey (NGS) is embarking on a height modernization program in which, in the future, it will not be necessary for NGS to create new or maintain old orthometric height benchmarks. In their stead, NGS will publish measured ellipsoid heights and computed Helmert orthometric heights for survey markers. Consequently, practicing surveyors will soon be confronted with coping with these changes and the differences between these types of height. Indeed, although “height’” is a commonly used word, an exact definition of it can be difficult to find. These articles will explore the various meanings of height as used in surveying and geodesy and present a precise definition that is based on the physics of gravitational potential, along with current best practices for using survey-grade GPS equipment for height measurement. Our goal is to review these basic concepts so that surveyors can avoid potential pitfalls that may be created by the new NGS height control era. The first paper reviews reference ellipsoids and mean sea level datums. The second paper reviews the physics of heights culminating in a simple development of the geoid and explains why mean sea level stations are not all at the same orthometric height. The third paper introduces geopotential numbers and dynamic heights, explains the correction needed to account for the non-parallelism of equipotential surfaces, and discusses how these corrections were used in NAVD 88. The fourth paper presents a review of current best practices for heights measured with GPS.

What Does Height Really Mean? Part II: Physics and Gravity by Thomas H. Meyer, Daniel R. Roman, and David B. Zilkoski

This is the second paper in a four-part series considering the fundamental question, “what does the word height really mean?” The first paper in this series explained that a change in National Geodetic Survey’s policy, coupled with the modern realities of GPS surveying, have essentially forced practicing surveyors to come to grips with the myriad of height definitions that previously were the sole concern of geodesists. The distinctions between local and equipotential ellipsoids were considered, along with an introduction to mean sea level. This paper brings these ideas forward by explaining mean sea level and, more importantly, the geoid. The discussion is grounded in physics from which gravitational force and potential energy will be considered, leading to a simple derivation of the shape of the Earth’s gravity field. This lays the foundation for a simplistic model of the geoid near Mt. Everest, which will be used to explain the undulations in the geoid across the entire Earth. The terms geoid, plumb line, potential, equipotential surface, geopotential number, and mean sea level will be explained, including a discussion of why mean sea level is not everywhere the same height; why it is not a level surface.

What does height really mean? Part III: Height Systems by Thomas H. Meyer, Daniel R. Roman, and David B. Zilkoski

This is the third paper in a four-part series considering the fundamental question, “what does the word “height” really mean?” The first paper reviewed reference ellipsoids and mean sea level datums. The second paper reviewed the physics of heights culminating in a simple development of the geoid and explained why mean sea level stations are not all at the same orthometric height. This third paper develops the principle notions of height, namely measured, differentially deduced changes in elevation, orthometric heights, Helmert orthometric heights, normal orthometric heights, dynamic heights, and geopotential numbers. We conclude with a more in-depth discussion of current thoughts regarding the geoid.