Matthew T. Rice

Visualizing 3D/4D environmental data using many-core graphics processing units (GPUs) and multi-core central processing units (CPUs)

Visualizing 3D/4D environmental data is critical to understanding and predicting environmental phenomena for relevant decision making. This research explores how to best utilize graphics process units (GPUs) and central processing units (CPUs) collaboratively to speed up a generic geovisualization process. Taking the visualization of dust storms as an example, we developed a systematic 3D/4D geovisualization framework including preprocessing, coordinate transformation interpolation, and rendering. To compare the potential speedup of using GPUs versus that of using CPUs, we have implemented visualization components based on both multi-core CPUs and many-core GPUs. We found that (1) multi-core CPUs and many-core GPUs can improve the efficiency of mathematical calculations and rendering using multithreading techniques; (2) given the same amount of data, when increasing the size of blocks of GPUs for coordinate transformation, the executing time of interpolation and rendering drops consistently after reaching a peak; (3) the best performances obtained by GPU-based implementations in all the three major processes, are usually faster than CPU-based implementations whereas the best performance of rendering with GPUs is very close to that with CPUs; and (4) as the GPU on-board memory limits the capabilities of processing large volume data, preprocessing data with CPUs is necessary when visualizing large volume data which exceed the on-board memory of GPUs. However, the efficiency may be significantly hampered by the relative high-latency of the data exchange between CPUs and GPUs. Therefore, visualization of median size 3D/4D environmental data using GPUs is a better solution than that of using CPUs.

Demarcating new boundaries: mapping virtual polycentric communities through social media content

The proliferation of social media has led to the emergence of a new type of geospatial information that defies the conventions of authoritative or volunteered geographic information, yet can be harvested to reveal unique and dynamic information about people and their activities. In this paper we address the identification and mapping of global virtual communities formed around issues of specific national interest. We refer to these connected virtual communities formed around issues related to a specific state as the polycentric virtual equivalent of that state. Identifying, mapping, and analyzing these virtual communities is a novel challenge for our community, and this is the subject we pursue in this paper. We present these communities relative to established conventions of statehood, address the harvesting of relevant geographical information from social media feeds, and discuss the challenge of visualizing such information. In order to do so we use the current geopolitical situation in Syria as a demonstrative example.

Supporting Accessibility for Blind and Vision-impaired People With a Localized Gazetteer and Open Source Geotechnology

Disabled people, especially the blind and vision-impaired, are challenged by many transitory hazards in urban environments such as construction barricades, temporary fencing across walkways, and obstacles along curbs. These hazards present a problem for navigation, because they typically appear in an unplanned manner and are seldom included in databases used for accessibility mapping. Tactile maps are a traditional tool used by blind and vision-impaired people for navigation through urban environments, but such maps are not automatically updated with transitory hazards. As an alternative approach to static content on tactile maps, we use volunteered geographic information (VGI) and an Open Source system to provide updates of local infrastructure. These VGI updates, contributed via voice, text message, and e-mail, use geographic descriptions containing place names to describe changes to the local environment. After they have been contributed and stored in a database, we georeference VGI updates with a detailed gazetteer of local place names including buildings, administrative offices, landmarks, roadways, and dormitories. We publish maps and alerts showing transitory hazards, including location-based alerts delivered to mobile devices. Our system is built with several technologies including PHP, JavaScript, AJAX, Google Maps API, PostgreSQL, an Open Source database, and PostGIS, the PostgreSQLs spatial extension. This article provides insight into the integration of user-contributed geospatial information into a comprehensive system for use by the blind and vision-impaired, focusing on currently developed methods for geoparsing and georeferencing using a gazetteer.

Crowdsourcing techniques for augmenting traditional accessibility maps with transitory obstacle information

One of the most scrutinized contemporary techniques for geospatial data collection and production is crowdsourcing. This inverts the traditional top-down geospatial data production and distribution methods by emphasizing on the participation of the end user or community. The technique has been shown to be particularly useful in the domain of accessibility mapping, where it can augment traditional mapping methods and systems by providing information about transitory obstacles in the built environment. This research paper presents details of techniques and applications of crowdsourcing and related methods for improving the presence of transitory obstacles in accessibility mapping systems. The obstacles are very difficult to incorporate with any other traditional mapping workflow, since they typically appear in an unplanned manner and disappear just as quickly. Nevertheless, these obstacles present a major impediment to navigating an unfamiliar environment. Fortunately, these obstacles can be reported, defined, and captured through a variety of crowdsourcing techniques, including gazetteer-based geoparsing and active social media harvesting, and then referenced in a crowdsourced mapping system. These techniques are presented, along with context from research in tactile cartography and geo-enabled accessibility systems.

Generating seamless surfaces for transport and dispersion modeling in GIS

A standard use of triangulation in GIS is to model terrain surface using TIN. In many simulation models of physical phenomena, triangulation is often used to depict the entire spatial domain, which may include buildings, landmarks and other surface objects in addition to the terrain surface. Creating a seamless surface of complex building structures together with the terrain is challenging and existing approaches are laborious, time-consuming and error-prone. We propose an efficient and robust procedure using computational geometry techniques to derive triangulated building surfaces from 2D polygon data with a height attribute. We also propose a new method to merge the resultant building surfaces with the triangulated terrain surface to produce a seamless surface for the entire study area. Using Oklahoma City data, we demonstrate the proposed method. The resultant surface is used as the input data for a simulated transport and dispersion event in Oklahoma City. The proposed method can produce the seamless surface data to be used for various types of physical models in a fraction of the time required by previous methods.

Integrating User-contributed Geospatial Data with assistive Geotechnology Using a localized Gazetteer

We present a methodology for using cartographic-based processes to alert the vision-impaired as they navigate through areas with transitory hazards. The focus of this methodology is the use of gazetteer-based georeferencing to integrate existing local cartographic resources with user-contributed geospatial data. User-contributed geospatial data is of high interest because it leverages local geographic expertise and offers significant advantages in dealing with hazard information in real-time. For blind and visionimpaired people, information about transitory hazards encountered while navigating through a public environment can be contributed by end-users in the same public environment, and quickly integrated into existing cartographic resources. For this project, we build collections of user-contributed geospatial updates from email, voice communication, text messages, and social networks.

A Comparative Analysis of Traveling Salesman Solutions from Geographic Information Systems

The Traveling Salesman Problem is one of the most prominent problems in combinatorial optimization, and is regularly employed in a wide variety of applications. The objective of this article is to demonstrate the extent of sub-optimality produced by Traveling Salesman solution procedures implemented in the context of Geographic Information Systems and to discuss the consequences that such solutions have for practice. Toward that end, an analysis is made of Traveling Salesman solutions from implementations in four Geographic Information System packages. These implementations are tested against the optimal solution for a range of problem sizes. Computational results are presented in the context of a school bus routing application. This analysis concludes that no Traveling Salesman implementation in GIS is likely to find the optimal solution when problems exceed 10 stops. In contrast, optimal solutions can be generated with desktop linear programming software for up to 25 cities. Moreover, one GIS implementation consistently found solutions that were closer to optimal than its competitors. This research strongly suggests that for applications with fewer than 25 stops, the use of an optimal solution procedure is advised, and that GIS implementations can benefit from the integration of more robust optimization techniques.

Flood mapping in the lower Mekong River Basin using daily MODIS observations

ABSTRACT In flat homogenous terrain such as in Cambodia and Vietnam, the monsoon season brings significant and consistent flooding between May and November. To monitor flooding in the Lower Mekong region, the near real-time NASA Flood Extent Product (NASA-FEP) was developed using seasonal normalized difference vegetation index (NDVI) differences from the 250 m resolution Moderate Resolution Imaging Spectroradiometer (MODIS) sensor compared to daily observations. The use of a percentage change interval classification relating to various stages of flooding reduces might be confusing to viewers or potential users, and therefore reducing the product usage. To increase the product usability through simplification, the classification intervals were compared with other commonly used change detection schemes to identify the change classification scheme that best delineates flooded areas. The percentage change method used in the NASA-FEP proved to be helpful in delineating flood boundaries compared to other change detection methods. The results of the accuracy assessments indicate that the −75% NDVI change interval can be reclassified to a descriptive ‘flood’ classification. A binary system was used to simplify the interpretation of the NASA-FEP by removing extraneous information from lower interval change classes.

Geospatial footprint library of geoparsed text from geocrowdsourcing

AOA: The research paper reports on the generation of geospatial footprints from geoparsed text associated with geocrowdsourced platial data collected and stored in the George Mason University Geocrowdsourcing Testbed (GMU-GcT). The GMU-GcT facilitates study of social dynamics, quality assessment, data contribution patterns, and position validation for geocrowdsourced spatial data, with a primary purpose of mapping transient obstacles and navigation hazards in a dynamic urban environment. This paper reports on the automated generation of geospatial footprints using open-source software, and discusses the role of automated geospatial footprints in quality assessment for automated position validation. A detailed, local gazetteer is used to store placenames and placename variants including abbreviated, slang, former, and jargon-based instances. Obstacle reports containing location descriptions are geoparsed and processed with the help of the GMU-GcT gazetteer to generate geospatial footprints, which are used in a quality assessment process to validate the position of obstacle reports. Continuing research with the GMU-GcT has produced fifteen characteristic footprints types, which are generated and grouped into simple, complex, and ambiguous categories. The open-source tools used for generating these general footprints include MapBox, TURF.js, jQuery, and Bootstrap.

Exploring alternative map products to enhance transportation option awareness

The steady increase in automotive vehicle usage in highly populated areas, leading to intensified traffic, suggests the need for new approaches to traffic management and commuting options. Maps as communication products might hold one key to unlocking guided alternative mode choices as standalone products and as service components. However, traditional paper and web-based maps might lack properties and affordances that will guide users to consider alternative commuting opportunities. Through careful determination of content, use and media, our research group assesses the emotional, visual and tactile properties of map affordances to create novel transportation maps. With future user testing and modification, transportation map alternatives could enable and encourage commuters to explore transportation alternatives and select a mode of transportation that is suitable for the changing landscape in commuting and mass transportation.