Surveying and Land Information Systems

 

VOLUME 59, No. 1 (1999)

Development of and Elevation Database for the U.S. Coastal Zone

Lincoln Pratson, David Divins, Tanja Butler, Dan Metzger, Mark Steele, George Sharman, Todd Berrgren, Troy Holcombe, and Richardo Ramos

Grids that integrate land and seafloor elevations are needed by planners using LIS/GIS software to manage the U.S. coastal zone which includes the country’s 200-mile offshore limit.  The national Geophysical Data Center is addressing this need by assembling a gridded database that merge the U.S. Geological Survey 3-arc-second DEMs with a vast compilation of hydrographic soundings collected by the National Ocean Service and various academic institutions.  This paper describes how the database is being constructed, using newly completed and now available grids of the eastern U.S. coastal zone (extending from Maine to Georgia) as an example.  The paper also describes the novel software that accompanies the grids on CD-ROM.  This software allows the user to navigate the CD-ROM, view grid images, and modify the grids for importation into GIS/LIS applications.

 

Using the HTDP Software to Transform Spatial Coordinates Across Time and Between Reference Frames*

Richard A. Snay

The Horizontal Time-Dependent Positioning (HTDP) software program may be used to predict the velocities and displacements associated with horizontal crustal motion, including that related to plate tectonics and earthquakes.  The software may also be used to account for this motion in updating positional coordinates and/or survey observations of one data to corresponding ones for another date.  Because HTDPP supports these activities for coordinates expressed in the North American Datum of 1983 (NAD 83) as well as for coordinates expressed in any official realization of the International Terrestrial Reference Frame (ITRF), this software may be used to transform 3-dimensional positional coordinates from one reference frame to another in a manner that rigorously addresses the relative motion between these frames.

 

 

 

Spatial Data Accuracy As Defined by the GSDM

Earl F. Burkholder

The concept of a global spatial data model (GSDM) which combines  horizontal and vertical spatial data into a single three-dimensional database is defined and described in Burkholder (1997a).  This paper describes how the GSDM accommodates Spatial data accuracy, providing specific equations for computing various accuracies.  A careful distinction is made between describing GSDM features and issues of implementation.  As a consistent set of equations and relationships, the GSDM can be used immediately by anyone.  Greater benefits will, however, accrue as the concepts gain acceptance and the GSDM procedures are standardized and adopted by the spatial data user community at large (implementation).

Elevation Comparisons from the 1994 Northridge, California, Earthquake GPS Leveling Project

Jay Satalich

GPS-derived orthometric heights are compared with benchmarks leveled after the 1994 Northridge, California, earthquake.  The heights of over 1200 North American Vertical Datum of 1988 (NAVD 88) benchmarks were estimated through geodetic leveling.  GPS observations were made at 94 benchmarks in the network, with an average spacing of 5km between adjacent stations.  GPS observations followed draft National Geodetic Survey Guidelines for estimating ellipsoid heights are the 2 cm (2s) accuracy standard.  GPS orthometric heights were estimated using the GEOID96 geoid model.  Using the GEOID96 height model, comparisons between GPS- and leveling-derived orthometric heights ranged from a minimum of –3.5 cm to a maximum of +10.3 cm.  Benchmarks located near the Santa Monica Mountains, Palos Verdes peninsula, and Angeles National Forest experienced the largest differences.

 

Evaluating the Accuracy of Differential, Trigonometric and GPS Leveling

Abdullah S.A. Alsalman

The results of six differential heightening measurement techniques for a precisely known level line were compared under various temperature ranges.  The static GPS technique was found to have comparable results with the third-order differential leveling without any significant degradation of accuracy at higher temperature ranges.  The worst relative increase in error due to temperature increase was in the trigonometric leveling technique.  The change in temperature from 20 degrees C to 40 degrees C caused increase in error by about 42, 14, and 55 percent for ordinary differential, stadia and trigonometric leveling, respectively.

 

Private Property, Public Rights, and Shifting Sands: The Public Trust Doctrine as a Source of Authority for Coastal Management Decisions*

Stephen T. Mague

This paper gas been condensed from Master’s work conducted by the author at the University of Massachusetts, Boston, integrating the science of coastal processes with current law and policy to create a sound legal framework for revised coastal armoring policy in the Commonwealth of Massachusetts. This condensed paper focuses on the Public Trust Doctrine, with limited discussion of coastal processes and the effects of seawalls on adjacent coastal areas and their natural resources. Readers interested in more detailed discussion on the effect of seawalls are directed to the references list in the original work and at the back of this paper.

 

Conversion is Out, Measurement Is In—Are We Beginning the Surveying and Mapping Era of GIS?

David W. Gibson

Many people are questioning the applicability and coverage of state regulatory statutes on surveying and mapping. Could it be that the legislature really believes that unlicensed “surveying and mapping of land, water, and space presents a significant threat to the public?” (1997 Florida Statutes).  At issue is whether new activities in geographic information systems (GIS) and global positioning systems (GPS) fall under regulation.  Most statutory definitions clearly cover professional services involving specialized knowledge of mathematics, science, and the legal requirements for the determination of the facts of size, shape, topography, orientation and legal or geodetic location of features on or near the Earth’s surface. Statutes usually state that no person shall practice surveying and mapping unless such a person is licensed.  Many questions emerge. What is surveying?  Is cartography a branch of surveying?  Is GIS activity a form of surveying? Perhaps some answers can be found in a brief review of GIS in relation to traditional surveying activities

 

 

 

 

 

The International Federation of Surveyors Commission 1: Professional Standards and Practice

Robert W. Foster

This paper describes Commission 1 (Professional Standards and Practice) of the International Federation of Surveyors (FIG).  The commission is defined and its primary areas of interest are described.  In future issues of Surveying and Land Information Systems all commissions will be presented in a comprehensive discussion of their composition and the people who will achieve them.

 

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Surveying and Land Information Systems

Vol. 59, No. 2 (199)

Airborne Laser Swath Mapping: Accuracy Assessment for Surveying and Mapping Applications

Ramesh L. Shrestha, William E. Carter, Mark Lee, Paul Finer and Michael Sartori

Evolving and emerging technological advances in laser-ranging instrumentation, phase difference kinematic Global Positioning System (GPS) positioning, Inertial Navigation Systems (INS), and the speed as well as the storage capacity of personal computers have all resulted in the development of a compact, lightweight, and energy-efficient Airborne Laser Swath Mapping (ALSM) system.  ALSM, also referred to as Light Detection and Ranging (LIDAR), can be performed using a light twin or single engine aircraft.  Flying at speeds of 200 to 250 kilometers per hour, at an altitude of 500 to 2,000 meters with scan angles of + or – (10 to 20) degrees, and at laser repetition rates of 2,000 to 25,000 pulses per second, it is possible to blanket the surface of the Earth with accurate elevations every 2 to 3 meters.  Swaths exceeding one kilometer in width and hundreds of kilometers in length can be mapped in just a few hours to produce accurate Digital Terrain Models (DTMs) economically and with turn-around times never before possible.  Operating costs, exclusive of the 1.2 million purchase of the instrumentation, can be as low as a few dollars per kilometer of single swatch coverage, and preliminary DTMs can be produced within hours of collecting the data.  This paper examines the accuracy of elevations from ALSM technology.  The results show that elevations accurate to + or – 5-10 cm can be obtained routinely.

 

Private Property, Public Rights, and Shifting Sands: The Public Trust Doctrine as a Source of Authority for Coastal Management Decisions (Part 2 of 2)

Stephen T. Mague

This paper has been condensed from Masters’ work conducted by the author at the University of Massachusetts, Boston, integrating the science of coastal processes with current law and policy to create a sound legal framework for revised coastal armoring policy in the Commonwealth of Massachusetts. This condensed paper focuses on the Public Trust Doctrine, with limited discussion of coastal processes and the effects of seawalls on adjacent coastal areas and their natural resources. Readers interested in more detailed discussion effects of seawalls are directed to the references listed in the original work at the back of this paper.

 

A Linear Mapping Approach to Map Conflation: Matching of Polylines

Sagi Filin and Yerahmiel Doytsher

This paper presents a new approach towards map conflation, based on transformation of linear features according to their positional inconsistency with respect to their counterpart elements. This approach is in contrast the traditional and commonly used node-based approach.  The suggested concept provides a more natural solution for the map conflation problem, since linear features are the dominant elements within maps.  The paper outlines a strategy, elaborating on the transformation between two counterpart features, the core of the proposed concept.  It discusses the properties of the desired transformation, evaluates the suitable transformation methods, and presents an algorithm adopted for the matching polylines.  The suggested algorithm may also be suitable for other applications such as map generalization and change detection.  

 

Land Information in the Federal Republic of Germany: State-of-the-Art

Hartmut Mueller

In Germany, all official land information is registered in the real estate cadastre and the legal land property register.  The real estate cadastre consists of documents in text and graphic form.  All land information, kept on paper in the past, is presently being transformed into digital databases.  This paper describes the progress of this work in different fields of land information, providing details about some of the problems involved, such as the choice of an appropriate data model and the specification of a feasible spatial data exchange standard.  The paper analyzes the solutions presently being applied and emerging future developments.

 

Landslides and Earthquakes Displacement of Land Survey Monuments and Land Lines

C. Albert White

This paper is a technical note on survey legal issues related to landslides and earthquakes. It was developed by C. Albert White as a report to the Bureau of Land Management, Oregon State Office, Branch of Geographic Sciences. White has contributed significant works to the cadastral community. He is a volunteer to the Bureau and, as evidenced by this paper, continues to provide his extraordinary insight for practicing surveyors. The graphics and case studies supporting Mr. White’s work can be found on the World Wide Web at http://www.or.blm.gov/or957/landreport/index.htm.

 

The International Federation of Surveyors Commission 2: Professional Education

Robert W. Foster

Surveying and Land Information Systems

Vol. 59, No. 3 (1999)

The BLM’s GCDB: A Shared Database

Daniel T. Mates

In the 1980’s the U.S. Bureau of Land Management (BLM) designed a Geographic Coordinate Database (GCDB) as a foundation for an automated land information system.  This coordinate database has been designed as a map product based on survey measurements to spatially portray boundaries and land parcels. The GCDB is often utilized by local governments as a basis for map control, and it is enhanced through cooperative agreements with the BLM. Federal, state, county, and local governments as a state, county, and local governments, as well as the private sector, are discovering the usefulness of GCDB.  The BLM will endeavor to constantly improve the product in the coming years.

 

Creating a County Mapping Control Network: A Work in Progress

Rj Zimmer

This article discusses the planning and development of a county mapping control network. The initial need was identified be a county, but the planning of the network involved federal, state, and local agencies and private land surveyors. The outcome was a plan for a multi-tiered mapping control network that will meet a variety of needs for years to come.

 

Automating the Parcel Mapping Process: The Montana Cadastral Project

Craig C. Bacino

The proliferation of computer systems capable of handling geographic data has led to a demand for digital data sets, including cadastral, or parcel, information. In Montana, this demand has initiated a formal project to create a statewide digital land ownership database. Several factors, including the rural nature of the state and limitations of budget and staff, prompted an alternative approach to digital cadastral mapping. The resulting application digitally maps a high percentage of the land area of each township by integrating the U.S. Bureau of Land Management Geographic Coordinate Database and the State of Montana property appraisal database. Parcels not captured by the application are mapped by contracted vendors using conventional methods not appended to the database.

 

Don’t Duck Metadata

Kris Larson, Gretchen Burton, Patty Scarrah, and Bob Snyder

Montana is one of the first states to widely implement metadata collection and establish a Metadata Coordinator position.  The state also serves as a national model for providing data and metadata through the National Spatial Data Infrastructure (NSDI).  This paper reviews Montana’s metadata history, highlighting the success and challenges that other states and regions might face in their own efforts to institute metadata collection and participate in the NSDI.

 

Montana’s Natural Resource Information System (NRIS) Streamlining Access to Important Information

Jim Stimson

The Montana Natural Resource Information Systems (NRIS) was created by the Montana Legislature out of a realization that information retains value only when it is easy to find and it is in a useable format. NRIS is an information provider to a wide range of entities within and outside of Montana. Enhanced services are provided to state and federal natural resources agencies that require resources beyond their immediate capabilities.  NRIS is funded from a number of sources and strives to provide affordable and accessible geographic information. Citizens, resource managers and decision-makers all benefit from Montana’s information investment. 

 

Washington State Cadastral Framework Project: Implementing the FGDC Cadastral Data Content Standard and Integrating Data from Multiple Sources

Gregory S. Tudor and Carrie Wolfe

The Washington Cadastral Framework Project is a National Spatial Data Infrastructure (NSDI) demonstration project intended to show the benefits of building partnerships, sharing costs and coordinating work, standardizing data and tools, speeding up application development, improving and documenting data, resolving data conflicts, and sharing data.  The Washington Cadastral Framework Project is broken down into two phases which are pilot projects designed to implement a standard cadastral data set to intergrate cadastral data from multiple data sources.  Phase 1 (September 1997 to September 1998) involves extending and implementing the Federal Geographic Data Committee (FGDC) Cadastral Data Content Standard in SDE/Oracle, populating the database with initial data, developing metadata on the data, and distributing the data over the other framework data content themes: Geodetic Control, Hydrography, Transportation, and Governmental Units.  Phase 2 (September 1998-September 1999) involves adapting the FGDC Cadastral Data Transfer Standard for data exchange, intergrating data from several representative partner sources (federal, state, regional, county, city, and private organizations), developing update-locking procedures for long transactions over the Internet, and automating the integrating process so that minimal intervention is required for enforcing standards and resolving conflicts.

 

 

 

Error Modeling and Analysis of Terrestrial Stereo Imaging Systems for Mobile Mapping

Chuang Vincent Tao

The design and development of a stereo imaging system for mobile mapping applications requires knowledge of the achievable system positioning accuracy, the effect of imaging system geometry on the object positioning accuracy, and of the accuracy requirements for the calibration of the imaging system. The errors of mobile mapping systems are mainly comprised of two components: the navigation component and the stereo imaging component. This paper presents a quantitative analysis in the above three aspects, focusing on errors from the stereo imaging component. The paper is organized into three parts: (1) estimation of error distributions and analysis of absolute and relative accuracy; (2) systematic examination of the error contributions of various imaging system parameters and development of a new method to optimally configure imaging parameters; and (3) derivation of the quantitative error models of the imaging system calibration errors and determination value to researchers, developers and users of mobile mapping systems. They will also be of interest to those who use digital cameras for photogrammetric applications.

 

The Impact of RTK GPS at Oregon Institute of Technology

Dennis D. Findorff and Marshall M. “Mark” Ager

This paper describes the need for, and the impact of, integrating RTK GPS into surveying education at Oregon Institute of Technology.

 

Differential Global Positioning Systems: Determination of Franklin-Lebanon Town Line, Fall 1998

Gregory Cohen

This paper reports on an independent study of differential global positioning systems carried out at the Civil & Environmental Engineering Department of the University of Connecticut.  It comprises an overview of global positioning systems and of the benefits of differential GPS, a description of the GPS equipment used in the study, an evaluation of goals and methods used to achieve them, and conclusions.

 

 

 

The International Federation of Surveyors Commission 3: Spatial Information Management

Robert W. Foster

This paper describes Commission 3 (Spatial Information Management) of the International Federation of Surveyors (FIG). The commission is defined and its primary areas of interest are described. This is the fourth in a series of articles on the nine commissions of FIG. The composition of the remaining six FIG commission, their goals, and the people who will achieve them, will be presented in future issues of Surveying and Land Information Systems.

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Surveying and Land Information Systems

Vol. 59, No. 4 (1999)

Establishment of a Parcel-based Land Information System in Korea

Yong-Il Kim and Sang-Su Kim

This paper describes the present status of developing a parcel-based land information system in Korea.  It also describes the cadastre reform currently taking place in the country and provides other technical information with the aim of forming conducive to further discussion among specialists in the field.

The Greater City and the Wishing Well

Donald G. Richards

This is a story about land and business—and the people who owned them—as it had played itself out at the dawn of the twentieth century in sleepy little Flint, in Michigan, which, eventually, turned into the site of the multimillion dollar business of General Motors.

 

Automatic Filtering and Classification of Raw Field Surveying Data

Eytan Gelbman and Yerahmiel Doytsher

The current methods for handling the “mixed field observations” involve manual operators, and they enable the use of modern computing and drawing software packages only through tedious editing and rearranging of the data.  This article describes a new and efficient solution for processing the field-surveyed data so as to obtain a fully automated procedure from the field measurement stage to the final stage of defining the spatial databases. The new method is based on implementing computer science ideas: wrappers, wrapper of wrappers, and mediators.  A very efficient procedure has been developed and implemented as a computer software package.  Several field tests comparing the traditional and the new methods display the impressive results of the applied algorithms, reducing the duration of the manual phase of the traditional method to 20 to 30 percent.

 

Accuracy Evaluation of the Geoid Height Model GEOID96 for the Rocky Mountain States

Vladimir S. Argeseanu

This study evaluates the geoid discrepancies (nominal, and offset and tilt corrected) of the NGS Data Sheets geodetic control in the Rocky Mountain States (Colorado, Idaho, Montana, Utah, and Wyoming).  The geoid discrepancies and associated statistics and statistical tests are used as indicators of accuracy assessment of the conversion model in the region.  It was concluded that the dominant error sources are the GPS ellipsoid heights.  At 0.683 confidence level, the height data are compatible with the data used to calculate the GEOID96 geoid height model over the conterminous United States.  At 0.95 confidence level, the uncorrelated and correlated errors are 6.4cm and 4.1 cm, respectively.

 

Accuracy of GPS-derived Orthometric Height in San Diego County, California

Wesley Parks

The accuracy of GEOID93 was evaluated using new estimates of ellipsoidal and orthometric height for 28 benchmarks in eastern and northeastern San Diego County, together with existing estimates for 17 benchmarks.  This analysis completes a series of investigations begun in 1992.  Results suggest that orthometric height can be estimated in San Diego County using precise vertical GPS-derived orthometric height is accurate to 3.4 cm at the 1-sigma confidence level.  If a West County-specific correction plan is used, results show that GPS-derived orthometric height is accurate to 3.3 cm at the 1-sigma confidence level.

 

 

 

The International Federation of Surveyors: Commission 4 Hydrography

Robert W. Foster

This paper describes Commission 4 (Hydrography) of the International Federation of Surveyors (FIG).  The commission is defined and its primary areas of interest are described. This is the fifth in a series of articles on the various commissions of FIG. In future issues of Surveying and Land Information Systems, all commissions will be presented in a comprehensive discussion of their composition and goals and the people who will achieve them.