URISA Journal
Table of Contents
Volume 19, Number 2

Download Volume 19, Number 2 in PDF format

In this issue:

• An Assessment of GIS-Enabled Walkability Audits
  Marc Schlossberg, Asha Weinstein Agrawal, and Katja Irvin
• Institutional and Organizational Barriers to Effective Use of GIS by Community-
  Based Organizations
  Ann-Margaret Esnard
• Coupling Multiagent Geosimulation and Spatial OLAP for Better Geosimulation
  Data Analysis
  Walid Ali, Bernard Moulin, Yvan Bédard, Marie-Josée Proulx, and Sonia Rivest
• An Interoperable Portal Supporting Prototyping Geospatial Applications
  Myra Bambacus, Phil Yang, John Evans, Marge Cole, Nadine Alameh, and Stephen Marley
• A Comprehensive Process for Linear Referencing
  Kevin M. Curtin, Greta Nicoara, and Rumana Reaz Arifin
• When Data Sharing Becomes Institutionalized: Best Practices in Local
  Government Geographic Information Relationships
  David L. Tulloch and Francis Harvey

Note: Complete text of Journal articles are in Adobe Acrobat (.pdf) format

A Digital Terrain Model for the Management of
Water Distribution Piping Nets: A Case Study

M.G. D’Urso and G. de Marinis

Version: 1/18/08
 

ABSTRACT: We illustrate the basic tasks which have been undertaken, with reference to a case study represented by a small town in the south of Italy, in order to generate a digital terrain model to be used as support for real-time management of water distribution piping nets. A graphycal interface has been implemented to connect the softwares employed for simulating the working conditions of the net and for generating the digital terrain model by showing how it allows the user for a real-time visualization of the plan of loads acting on the net and the relevant variations associated with regulation manoeuvres. Thus, it becomes possible for public companies supplying water distribution to address both a rational planning of water resources, reducing wastes due to losses in the nets or bad functioning, and an effective monitoring of the emergencies caused by breaks and/or substitution of pieces of pipes.

Consumer-grade GPS Measurement Accuracy in Open and Urban Settings

Anonymous

Version 1/3/08

ABSTRACT: Consumer-grade GPS receivers are available for several hundred dollars or less and can be used for many measurement applications including collecting data for information systems provided that acceptable accuracies are achieved. We examined the measurement accuracy and reliability of six identical contemporary consumer-grade GPS receivers that collected data simultaneously at two distinct test courses. One test course was located in an open field while the other test course was placed under tree canopy and had several buildings blocking a view of the horizon. We also varied data collection techniques by using one, ten, and 30 point averaging intervals to examine the influence of different intervals on measurement accuracy and precision. Measurement accuracies for all GPS receivers averaged 1.8 m from true position at the open field course and 3.8 m from true position at the tree canopy course with variations depending on when the courses were visited. We also found that although six identical receivers were used to collect measurements simultaneously and in close proximity to one another, there were statistically significant differences in the measurement accuracies of the receivers. No statistically significant influence of different point averaging intervals (1, 10, and 30) on measurement accuracy was detected.

Reading, ‘Riting, ‘Rithmetic...GIS - The Fourth “R” in Education?

(Version 11/7/07)

Donna L. Goldstein

ABSTRACT: For better or worse, computers have revolutionized every aspect of our lives. As we quickly make the transition from an industrial to an information age, computer literacy skills have become a basic necessity. Technology skills are now referred to as the "Fourth R" in education. To successfully learn and use GIS (Geographical Information Systems) technology, one must incorporate the skills of reading, writing, and arithmetic. Understanding and utilizing a GIS system requires a holistic combination of reading instructions, data, and maps; writing hypotheses, reports, and presentations; and using arithmetic to understand queries and spatial analysis. Thus the 4th R as it relates to GIS is a new elevated skill that incorporates the three original R’s in education. Teaching GIS may be just the boost our public educational system needs to adequately prepare students for entrance into the emerging global society.

Automatic Generation of High Quality 3D Urban Buildings from Aerial Images

(Version 11/5/07)

Ahmed F. Elaksher and James S. Bethel

ABSTRACT: High quality 3D building databases are essential inputs for urban area Geographic Information Systems. Since manual generation of these databases is very costly and time consuming, the development of automated algorithms is of great need. This article presents a new algorithm to automatically extract accurate and reliable 3D building information. High overlapping aerial images are used as input to the algorithm. Radiometric and geometric properties of buildings are utilized to distinguish building roofs in the images. This is accomplished using image segmentation and neural network techniques. A rule-based system is used to extract the vertices of the roof polygons in all images. The 3D coordinates of these vertices are computed using photogrammetric mathematical models. The algorithm is tested on a number of buildings in a complex urban scene. Results showed a detection rate of 99% and a false alarm rate of 5.0%. The root mean square error for the extracted building vertices is 0.25 meter using 1:4000 scale aerial photographs scanned at 30 micron.

Flint River Basin Plan Implementation: Hydrologic Information Systems for Surface Water Permitting

(Version 10/29/07)

Amber Alfonso, James E. Hook and Kerry Harrison

ABSTRACT: Water resources management in Georgia has become increasingly complex. Recent droughts, lawsuits by neighboring states, and in-state competition for water have created a patchwork of new regulations on water withdrawal permits. In some watersheds, streams have designated protection corridors; in others, subwatersheds have withdrawal limitations. In order to efficiently and objectively apply location-specific regulations, State agency hydrologists and geologists need geospatial evaluation tools. This research develops methodologies for joining and relating spatial and temporal data using the Arc Hydro data model and geodatabase functionality for surface water evaluations. The features contained within this hydrologic information system are employed as inputs to the process model, which is in turn used to create appraisal reports. The research was done under contract to the Georgia Department of Natural Resources, Environmental Protection Division.

Using GIS to Quantify the Anthropogenic-Induced
Raven Threat to Desert Tortoise

(Version 10/4/07) 

Blodwyn M. McIntyre, Thomas E.J. Leuteritz and Mark P. Kumler

ABSTRACT: Common ravens (Corvus corax) are a threat to desert tortoise (Gopherus agassizii) populations in the Mojave Desert. The U.S. Army is expanding its National Training Center (NTC) at Fort Irwin near Barstow California. This will involve the translocation of several hundred tortoises from the expansion area to several new sites outside of the base. In this study we use GIS to quantify the threat ravens pose to desert tortoises in the translocation area prior to initial tortoise release. A survey of ravens within the translocation area allows for a comparison to raven densities at this site in the future. A spline with barriers analysis was used to create a density surface over the translocation area. According to this analysis, raven densities were highest in association with anthropogenic features, linear features, and features with vertical strata. This paper may be the first to actually make a spatially-based connection between highway rest stops and elevated raven densities based on real data.  The study also provides scientists with a baseline for ongoing research into the effectiveness of tortoise translocation.