1999 01 20       

[2014 02 14 - With valentine regard for every surveyor, from John Filson on, original links are updated with minimal edits for this 15 year update.]

The Surveyor’s GIS

The Mandate

With no fear of hyperbole, let it be said: no profession has been forced to change more than Surveying in this last 5 years of the millenium. Before 1995, few Surveyors had cracked the mystery of computers beyond some DOS commands. And at mid-decade the preoccupation was with the revolutionary transition to electro-optic distance measurement and digital data collection. While in 1995 few Surveyors thought much about geodesy, since 1997, every Professional Surveyor has been responding to the challenge to become a better geodesist. Now in 1999, having barely accomplished the transition to electronic surveying, still learning geodesy, the Surveyor is confronting the ultimate Information System: Geographic. Somehow that boring 7th grade topic has become the avant-garde.

Perhaps some may take shelter in the words of Mark Twain, who said about Cincinnati: "If the world comes to an end, just move to Cincinnati since everything happens there 10 years later". But Twain’s world one century ago seems to turn much faster now. We are in the midst of an astounding 5-year revolution. Those who haven’t learned to surf may be soon swallowed by the wave strangely coincident with El Nino.

Last year, the California BOard for Professional Engineers and Land Surveyors (BOPELS) issued a simple clarification of established code in the California Land Surveyors Act. Business and Professions Code Section 8726 {http://www.dca.ca.gov/pels/} defines the scope of responsibility of the Professional Surveyor. After enumerating the dozen categories of what surveyors do best, in items a to l, item m refers all this work to the digital age; the Surveyor:

  • (m) Creates, prepares, or modifies electronic or computerized data

  • in the performance of the activities described in subdivisions (a),(b), (c), (d), (e), (f), (k), and (l).
  • To clarify this clause in response to recent concerns about the impact on public health and safety of an inaccurate GIS, the Board issued Policy Resolution #98-03, approved July 31,1998:

  • The creation, preparation and distribution of data contained in GIS and LIS, by public agencies and private companies is becoming more prevalent. Many of the functions or activities being performed relative to the preparation of a GIS or LIS are in connection with the practice of civil engineering or land surveying. Some activities affect the health, safety, and welfare of the public.

    Electronic or computerized data created, prepared, or modified in connection with those subdivisions exhibited within Geographic Information Systems (GIS) and/or Land Information Systems (LIS) require licensure as a professional land surveyor or registration as a professional civil engineer authorized to practice land surveying.

  • To Mark Twain’s credit, it hasn’t happened yet in Cincinnati, nor in Ohio, but the trend is discernible. This policy resolution, albeit grammatically incorrect, overcomes undying contention by non-surveyors led by Bruce Joffe (a U.C.-Berkeley schooled Architect with a Master of City Planning from MIT). His case is articulated in the current issue of GeoInfo Systems magazine, where he serves on the Editorial Advisory Board [Vol 9:1, Jan 1999, "Fuzzy Data or Split Hairs? Exploring the Need for Surveyors in Developing GIS Base Maps"].

    Couple this trend with new Ohio Governor Robert Taft’s challenge, "Our frontier is knowledge and technology – a place where Ohio must be a leader among states and nations.", and we find the Surveyor at the forefront of the new age, because the GIS is the new foundation for knowledge about our world and represents a convergence of the technological revolution.

    So, where do we begin?

    While the term GIS typically refers to something managed by government, it is expected that the concept of GIS will continue to generalize such that each of us will manage a personal GIS as an important interface to the world. Indeed, spaceship Earth is the single, uncontested unifying factor for all humans. Witness the increasingly popular, web-based, Microsoft GIS at http://map.bing.com/, or [2002] emergence of MapPoint.Net.

    OK, GIS is important, and we need to learn about GIS; but what does it cost? Wrong question; since the cost of GIS may be $0. A better question is, what is the value of GIS to the Surveyor? For those managing the practice of Surveying, the concept of Executive Information System merges with that of Geographic Information System. The practice of surveying is especially well represented using GIS. The primary deliverable by the Surveyor is a digital point located geographically. Practically all information that comes through the Surveyor’s office can be stored best in digital form along with the project to which it relates.

    The domain of the Surveyor typically extends over several counties or even states. On the other hand (provincial) governmental GIS is typically bounded and discontinuous across governmental boundaries. For example, what GIS encompasses Dayton and Columbus? OK, the answer is the Ohio GIS –but at the cost of accuracy and detail. Now, what GIS encompasses Cincinnati and Northern Kentucky? The answer, is the Surveyor’s GIS.

    That is, for the moment, we are not interested in any other GIS. We will build one "from scratch" to serve only the needs of the Surveyor. We are driven by the rewards obtained from organizing our own (proprietary) work history and information needs (Executive Information System) as we develop the necessary proficiency to indeed meet the challenge of rising expectations of Surveyors by the Public.

    So where do we begin? Consider Scope and Context. What is the context for our GIS? It is not county; it is not state; the next level is federal. Fortunately, the federal government anticipates our needs. The Office of Management and Budget (OMB) {http://www.whitehouse.gov/omb/circulars/index-budget.html} is the declarative arm of the President of the United States (Executive Branch). Declarations are systematically issued, since 1948, as "Circulars". The Bush Administration issued Circular A-16 Revised (updating the original LBJ edict in 1967) on 1990oct19, directed to all department heads of the Executive Branch on the subject: "Coordination of Surveying, Mapping, and Related Spatial Data Activities".

    Circular A-16 defines the authoritative, comprehensive nation-wide civilian GIS, now termed the National Spatial Data Infrastructure, NSDI. Administration of the NSDI is entrusted to the highest-level assembly of federal officials. Chaired by the Secretary of the Interior (currently Bruce Babbitt), the Federal Geographic Data Committee, FGDC, is comprised of members from virtually every Federal Agency with interest in GIS. It’s organization is depicted in Figure 1, taken from the 100-page, 1998 publication: Framework, Introduction and Guide.

     

    Figure 1

     

    While composition of the FGDC is primarily federal, also included is the National States Geographic Information Council and the National Association of Counties. However, the concept of the Framework includes and welcomes participation by groups and individuals from all sectors, related to each other in the form of a network as depicted in Figure 2.

     

    Figure 2

    The Surveyor, limited only by reluctance, is a welcome participant in the Framework. A few hours on the internet is likely to bear fruit. More links are provided later in this article. Regarding Ohio Framework activities, the Ohio Geographically Referenced Information Program, OGRIP {http://ogrip.oit.ohio.gov/} is considered the Ohio GIS Coordinating Group from the standpoint of the FGDC. Thus OGRIP is an Ohio point of contact in getting involved, and getting guidance and data. In 1996, the FGDC began to support selected GIS consortia to test and refine the framework concept. OGRIP has completed an NSDI Competitive Cooperative Agreement Program, describing large-scale feature classification and usage statewide. Another program involving OGRIP has resulted in a state-wide coverage of digitized 7.5’ USGS quad maps. The Digital Line Graph (DLG) files can be downloaded by FTP and then typically converted to ESRI, AutoCAD or other usable formats.

    While in 1999 it appears INDOT {www.state.in.us/dot} and the Universities were not in sync in representing the Coordinating Group in Indiana, in 2014:  http://www.in.gov/gis/.  The Kentucky agency in 2014 is the Office of Geographic Information (OGI) {http://ogi.ky.gov}. In 1999, OGIS was recently granted funding from FGDC as a Federal Demonstration Projects Program focusing on road centerlines. Already in place are two KY programs: (1) Rather than digitize quad maps into DLG vector files, the KY program scanned the USGS maps into a statewide mosaic of Digital Raster Graph (DRG) files; (2) statewide panchromatic scanned aerial photography.

    While the Framework also refers to this unbounded network of people; physically, the term Framework represents a simple, nationwide, consistent basemap that serves as the common denominator for all GISs within the U.S. See Figure 3. It is expected, at more local levels, that the skeletal Framework is "fleshed out" to serve more local needs (applications). Thus, the Framework is the preferred starting point for any GIS in the U.S.

     

    Figure 3

     

    A GIS may have an unlimited number of layers. The 7 foundation layers of the Framework, depicted in Figure 3, are thought to be both essential and universally of interest in representing geography. All of these layers are important to the Surveyor and it is in the interest of Public Safety that features on these layers are as accurately positioned as possible. Of course, based on the accuracy of USGS quad maps, the NSDI starting point is insufficient for the Surveyor’s GIS except as a comprehensive vicinity map for all the work areas defining the extent of the Surveyor’s GIS. More digging may uncover more accurate, local GIS datasets such as is represented by the Cincinnati Area GIS (CAGIS). However, a local GIS is less likely to conform to the Framework primarily based on our next topic.

     

    Coordinate System

    Figure 4

    The FGDC recommends that the coordinate system used for the Framework meet the criteria of global consistency. This is most convenient as we expand the extent of our GIS beyond state boundaries. Therefore the preferred coordinate system is based not on a plane, but on a 3-dimensional space in which Earth occurs as nearly a sphere. The datum (reference surface) is an ellipsoid with origin at Earth’s Center of Mass (CoM). While there are other candidates, basic units of measure in a spheroidal coordinate system are typically latitude and longitude expressed in angular decimal degrees of rotation from an origin plane. As commonly used, the origin of latitude is the equatorial plane (which includes CoM). The origin of longitude is the plane (also including CoM) defined by the axis of rotation of Earth and a point arbitrarily chosen in a borough of London on the Thames River at the Royal Greenwich Observatory. The arc representing the intersection of the datum and this plane is termed the Prime Meridian, at 0 of longitude.

    Such a system is maintained by the International Earth Rotation Service, IERS. This service, headquartered at the Paris Observatory, was started on day one of 1988 by the International Union of Geodesy and Geophysics (IUGG) and the International Astronomical Union (IAU). IERS is one of 11 services sponsored by the Federation of Astronomical and Geophysical Data Analysis Services (FAGS). Another FAGS service, the International GPS Service, IGS, was established in 1994 by the International Association of Geodesy, IAG, to support the IERS by collecting GPS observations from a global network of continuously operating reference stations. Just as NGS in Washington, D.C. administers the nationwide network of 140 CORS; IGS, hosted by NASA at the Jet Propulsion Laboratory in Pasadena at the California Institute of Technology (CalTech), compiles observations from nearly 200 stations globally distributed.

    The IERS maintains 2 primary reference systems: celestial and terrestrial; and thereby determines the insertion of "leap seconds" into Universal Time Coordinated, UTC (father Time). The celestial reference system provides the context for the Earth-Centered, Earth-Fixed terrestrial reference system. Realization of the latter is made possible by 3 technologies in conjunction with GPS: Very Long Baseline Interferometry (VLBI), Dopler Orbitography by Radiopositioning Integrated on Satellite (DORIS), and Satellite Laser Ranging. The IGS network of GPS reference stations form a global polyhedron of baselines which are periodically least-squares adjusted to a set of coordinates and reported annually as the International Terrestrial Reference Frame, ITRF. Each year there is a new adjustment; each year residuals decline along an asymptotic curve toward zero.

    The United States Department of Defense, by way of the National Imagery and Mapping Agency, NIMA, (formerly Defense Mapping Agency) has established the Global Positioning System, GPS, coincident with the ITRF. In the current document, DOD WGS84: Its Definition and Relationship with Local Geodetic Systems [1997 07 04], on page 2-2:

  • Readers should note that the definition of the WGS 84 Conventional Terrestrial Reference System has not changed in any fundamental way. This CTRS continues to be defined as a right-handed, orthogonal and Earth-fixed coordinate system which is intended to be as closely coincident as possible with the CTRS defined by the IERS or, prior to 1988, its predecessor, the Bureau International de l’Heure (BIH) [translation: Bureau of Time].
  • While the set of monitoring stations used by DOD is slightly different than that used by IGS, there is overlap; and "By constraining the solution to the appropriate ITRF, the improved coordinates for these permanent DoD stations represent a refined GPS-realization of the WGS 84 reference frame." [ibid, page 2-3]. Thus, we are correct in making reference to either reference system interchangeably and shall hereafter opt for the ITRF. Specific reference shall always include the adjustment epoch, such as: ITRF96, the current basis for WGS 84 (G873), where "G" refers to GPS and "873" indicates the GPS week number up to which the data supporting the epochal adjustment was used.

    In as much as we now enjoy a globally consistent and accurate coordinate system for which we have consistent, reliable, accurate measuring tools, it makes sense, when building a GIS, to consider also founding the GIS in this Frame. The drawbacks to use of this coordinate system are basically two-fold: (1) sources of data are rarely provided in updated ITRF coordinates. (2) civil projects traditionally are based on a planar surface frame to facilitate distance computations. The solution, in both cases, involve:

     

    Projections

    While the Surveyor’s GIS is founded on the ITRF, common sources of data, other than GPS data, rarely are provided in updated ITRF coordinates. However, since there are tools to convert data bi-directionally between the ITRF and other coordinate systems, GIS data can be pre-processed for conformance with ITRF. Further, commonly available software supporting the viewing of geographic coordinate-based data supports the dynamic projection of this data for interactive distance determinations and map production. Thus, the price for enjoyment of globally-consistent Geographic Information Systems is mastery of the projection process.

    Today, nearly every Surveyor is equipped with software tools from one or more of three common providers: Autodesk, Intergraph, and Environmental Systems Research Institute, ESRI. In our presentation and demonstration, we will focus on tools from Autodesk and ESRI.

    With caveats in 1999 that are expected to subside as we enter the next millenium, these software tools enable building consistent models of our world which then facilitate the communication and registration of geographic data among increasing sets of users participating in the NSDI.

     

    MetaData

    Ultimately a feature, point-by-point, is located on the GIS. The existence of an individual feature on the GIS implies a data record in a table to which fields of data may be added elaborating what is considered useful knowledge about the feature. As data fields (attributes) are added and more records (features) are added to the table, the table becomes a repository of information. But large drawings and tables are time-consuming to download and open; so before investing the required time to look directly at the data, it is desirable to learn about the structure of the table before taking on the burden of accessing its content.

    MetaData is simply data about data, similar to a Table of Contents for a book. Since geographic data can be time-consuming to browse directly, metadata becomes an important adjunct to facilitating use of the GIS. The most graphic depiction of metadata is the preview window provided in AutoCAD when browsing for a file to open and edit. This also illustrates that metadata is not easy. It took one of the world’s most driven software companies 13 iterations over a decade to enable the user to easily spin through 20 drawings, searching for the right one, during the time it would otherwise take to open just one. In addition to this programmer-composed, quick visual indication of an AutoCAD drawing, other metadata about that drawing file may include the log-in name who saved the file, date, file size, title, etc. Essentially, metadata is minimal, summary information enabling accurate expectations about the content of data without paying the price of actually getting it.

    The FGDC last year completed its update of the recommendation for MetaData: Content Standard for Digital GeoSpatial MetaData, FGDC Version 2, 98jun. This standard, though unwieldy, is an effort to both accommodate all classes of information that may be included in a GIS and to provide a structure for the presentation of this information consistent with other like forms of data. Figure 5 may be considered metadata for this metadata standard. As the GIS evolves into the Knowledge System and common model of our world, metadata grows hierarchically, chunking details into levels that can be viewed from the top-most, big-picture level while providing for "drilling" down to the specific object of our query.

    Especially important for the Surveyor is the aspect of metadata which characterizes the quality of the data, or, in particular, the quality of the position. It is no longer sufficient to locate a property corner by reporting coordinate values. Metadata includes information about the SEP, Spherical Error Probable. This information today, is commonly left behind in closure reports and associated data such as RMS and residuals in a spatial analysis. The GIS enables the Surveyor to include data fields indicating the quality of each numeric value determining the point’s location in the GIS.

    For every problem managing information, there are solutions in the form of software. Just as the U.S. Army Corps of Engineers developed CorpsCon to facilitate user management of coordinate systems, the Corps has authored an aid for managing metadata.  In 1999 CorpsMet95 was shareware offered at http://Corpsgeo1.usace.army.mil.  The modern link http://www.fgdc.gov/metadata/geospatial-metadata-tools  is a link from the page at http://www.fgdc.gov/. Here are some other links of interest:

    ACSM: http://www.acsm.net/  http://en.wikipedia.org/wiki/American_Congress_on_Surveying_and_Mapping

    Autodesk: www.autodesk.com

    ESRI: www.esri.com

    FGDC http://www.fgdc.gov/

    FGCS: (Subcommittees) updated:   http://www.fgdc.gov/participation/working-groups-subcommittees/fgcs/

    GIS Links: U. Edinburgh: http://www.geos.ed.ac.uk/geography/

    IAG: www.gfy.ku.dk/~iag/    2007 07 14 >>  http://www.iag-aig.org/   to Muenchen!

    IERS: hpiers.obspm.fr

    IGS: igscb.jpl.nasa.gov

    IUCC:  http://www.iugg.org/

    IUSM: lareg.ensg.ign.fr

    USACE: www.usace.army.mil

    CorpsCon: crunch.tec.army.mil/software/corpscon/corpscon.html    even wiki makes no sense of "corpscon"

     

     

     

    Figure 5

     

    Information

    The Geographic Information System may be likened to the great Pyramids. A GIS, properly administrated, is potentially more permanent (since data incurs no wear and tear from the elements) and represents an investment by many individuals to create an enduring structure that can continue serving its purpose indefinitely.

    What is the purpose of a GIS? It is the store. It is where information is stored and from where information is retrieved. Before GIS, information had no globally-consistent organizing framework on which all knowledge could be stored. Certainly, some knowledge (e.g. medical) has less requirement or dependency on geography. However, the master database is located somewhere (the hard drive is physically located); and this location may be searched for information even while the informational object may have no relation to geography.

    In fact, as long as knowledge is based on knowledge workers, all knowledge has a connection to location, if not a dependency. For example, I want to search for knowledge about angiomas and techniques for removal. I may start my search via the internet with an entry on the browser seach box. But more efficient than searching the entire internet is discovering the location of specific medical databases and gateway access to such databases. Such a specific engine is likely located at, e.g., the U.Cincinnati College of Medicine which is modeled on the GIS and provides a gateway to (geographically-independent) subject searches on angiomas. In any case, the topical search results is a set of articles whose authors are typically based at medical centers. For any subject, one department at one medical center may achieve a level of notoriety for excellence or at least specialization that provides the best answers to the query at hand. Geography indeed facilitates the search for information that is ultimately independent of position. Geography plays a significant role in organizing knowledge.

    At this formative stage, at the beginning of the millenium, we are placing the initial stones for the foundation of our GIS pyramid. The GIS will likely be around at the end of the millenium. It will serve many generations of humans increasingly efficient at managing resources, and managing an electronic virtual reality now grown beyond the confines of Spaceship Earth. The GIS is an awesomely realistic model of the world, automatically encoding knowledge, enabling high-speed travel, both physically through space and virtually, simulating being there, indeed even at the scene where news occurs.

    It is the work of the Surveyor to lay these foundation stones properly to achieve the best economy as the foundation rises with unending elaboration. If our vision is limited, the GIS is a patchwork, loosely jointed fabric. But if we are geodesists, we are building a consistent, increasingly realistic, shareable model of our world for the benefit of all who come after us.

    Ohio state motto: "With GOD, all things are possible."

    _______________________________________

    References

    1. Federal Geographic Data Committee 1997, Framework, Introduction and Guide

    2. National Imagery and Mapping Agency, Technical Report TR8350.2, Third Edition, 4 July 1997, Department of Defense World Geodetic System 1984, Its Definition and Relationships with Local Geodetic Systems

    3. GeoInfo Systems, Vol 9:1, Jan 1999, "Fuzzy Data or Split Hairs? Exploring the Need for Surveyors in Developing GIS Base Maps"

    4. john's Bibliography on Surveying