Spatial News

SIE alumnus Xavier Lopez inducted into Francis Crowe Society

Wed, 14 May 2008 09:01:00

SIE alumnus Xavier Lopez was inducted into the Francis Crowe Society as a Distinguished Engineer at the annual Francis Crowe Society ceremony held Saturday, May 10, 2008, at Hauck Auditorium on the UMaine campus. The purpose of the Francis Crowe Society is to recognize UMaine engineering graduates as they accomplish the formidable goal of completing their engineering degrees and to recognize others who have made considerable engineering contributions and honored the profession. Lopez graduated from UMaine in 1998 with a Ph.D. in Spatial Information Engineering. Since then, he has advanced to the position of Director of Oracle Corporation's Location Services group where he leads Oracle's efforts to incorporate spatial technologies across Oracle's database, application server, and eBusiness applications. He has been active in numerous academic and government research initiatives on geographic information, is the author of a book on government spatial information policy, and has authored over 50 scientific and industry publications in areas related to spatial information technology. Congratulations to Xavier on receiving this distinguished award! (pictured: SIE Professor Kate Beard, Xavier Lopez, SIE Department Chair Mike Worboys)

SIE students graduate - UMaine Commencement May 2008

Mon, 12 May 2008 10:59:00

University of Maine held its 206th Commencement on Saturday, May 10, 2008, at the Alfond Arena. Three SIE graduate students received their Master's degree in Spatial Information Science and Engineering. Three SIE undergraduate students received their Bachelor's degree in Information Systems Engineering. The SIE faculty hosted a celebratory luncheon in the department library where family and friends joined them in congratulating our graduates on their achievements, after which all proceeded to the Alfond Arena for the formal commencement ceremony. Congratulations graduates from all of us and we wish you the best for the future!

Master's in SIE graduates: Jeremy Onysko, Isolde Frank, Vijay Venkataraman

Bachelor's in ISE graduates: Ben Weber, Gabriel Irvine-McDermott, Steve Horn

Seniors model UMaine campus in 3D with Google Earth and visualize UMaine Event calendar: ISE Capstone Project

Thu, 08 May 2008 14:16:00

ISE seniors Ben Weber and Steve Horn presented their Capstone project on May 6, 2008, in the SIE library, Boardman Hall. For the past two semesters they have been working on completing a campus model for Google Earth under the guidance of SIE Professors Harlan Onsrud and Silvia Nittel. With contributions from students in UMaine's New Media Department, Ben and Steve have been able to model a good portion of the UM campus. Their current web page serves as a way to view campus events in this model along with resources for continued expansion and improved modeling of the campus. The project has advanced to the point where this new capability could be added to the Campus Calendar on UMaine's website. This addition to the UM website, if accepted, would link users to the Capstone project's event search page where the 3D model and campus event information would be available for download to Google Earth. Great job guys! (pictured: Steve Horn (l.), Ben Weber (r.))

Identifying factors of geographic event conceptualisation

Tue, 29 Apr 2008 15:27:00

Klippel, A., Worboys, M. and Duckham, M., 2008, Identifying factors of geographic event conceptualisation. International Journal of Geographical Information Science, 22, pp. 183-204.

The present paper examines whether the formal topological characterisation of spatial relations between moving geographic regions provides an adequate basis for the human conceptualisation of motion events for those regions. The paper focuses on gradual changes in topological relationships caused by continuous transformations of the regions (specifically, translations). Using a series of experiments, the conceptualisation and perception of conceptual neighborhoods is investigated. In particular, the role of conceptual neighborhoods in characterising motion events is scrutinised. The experiments employ a grouping paradigm and a custom-made tool for presenting animated icons. The analysis examines whether paths through a conceptual neighborhood graph sufficiently characterise the conceptualisation of the movement of two regions. The results of the experiments show that changes in topological relations - as detailed by paths through a conceptual neighborhood graph - are not sufficient to characterise the cognitive conceptualisation of moving regions. The similarity ratings show clear effects of perceptually and conceptually induced groupings such as identity (which region is moving), reference (whether a larger or a smaller region is moving), and dynamics (whether both regions are moving at the same time).

Conceptual Neighborhoods of Topological Relations between Lines

Fri, 25 Apr 2008 12:29:17

R. Reis, M. Egenhofer, and J. Matos, Conceptual Neighborhoods of Topological Relations between Lines, in: A. Ruas and C.Gold (eds.), The 13th International Symposium on Spatial Data Handling (SDH 2008), Montpellier, France
Springer, June 2008.

Conceptual neighborhood graphs capture the similarity among qualitative relations. This paper derives the graphs for the thirty-three topological relations between two crisp, undirected lines and for the seventy-seven topological relations between two lines with uncertain boundaries. The analysis of the graphs shows that the normalized node degree increases, from the crisp to the broad-boundary lines, roughly at the same degree as it increases for crisp lines that are transformed from R1 into R2.

Perceptual Sketch Interpretation

Fri, 25 Apr 2008 12:27:09

Markus Wuersch and Max J. Egenhofer, Perceptual Sketch Interpretation, in: A. Ruas and C.Gold (eds.), The 13th International Symposium on Spatial Data Handling (SDH 2008), Montpellier, France Springer, June 2008.

An automated extraction of regions from sketches can be of great value for multi-modal user interfaces and for interpreting spatial data. This paper develops the Perceptual Sketch Interpretationalgorithm, which employs the theory of topological relations from spatial reasoning as well as continuity and good gestalt from gestalt theory in order to model people's perception. The Perceptual Sketch Interpretation algorithm extracts regions iteratively, removing one region at each a time, thus making the remaining sketch simpler and easier to interpret. The evaluation of the algorithm shows that the use of gestalt theory empowers the algorithm to correctly identify regions and saves processing time over other approaches.

Spatial Reasoning with a Hole

Fri, 25 Apr 2008 12:23:59

Max J. Egenhofer and Maria Vasardani, Spatial Reasoning with a Hole, in: S. Winter, M. Duckham, L. Kulik, and B. Kuipers (eds.), Conference on Spatial Information Theory (COSIT '07), Melbourne, Australia, Lecture Notes in Computer Science, Vol. 4736, Springer, pp. 303-320, September 2007.

Cavities in spatial phenomena require geometric representations of regions with holes. Existing models for reasoning over topological relations either exclude such specialized regions (9-intersection) or treat them indistinguishably from regions without holes (RCC-8). This paper highlights that inferences over a region with a hole need to be made separately from, and in addition to, the inferences over regions without holes. First the set of 23 topological relations between a region and a region with a hole is derived systematically. Then these relations' compositions over the region with the hole are calculated so that the inferences can be compared with the compositions of the topological relations over regions without holes. For 266 out of the 529 compositions the results over the region with the hole were more detailed than the corresponding results over regions without holes, with 95 of these refined cases providing even a unique result. In 27 cases, this refinement up to uniqueness compares with a completely undetermined inference for the relations over regions without holes.

Metric Details of Topological Line-Line Relations

Fri, 25 Apr 2008 12:20:06

Kostas Nedas, Max J. Egenhofer, and Dominik Wilmsen, Metric Details of Topological Line-Line Relations International Journal of Geographical Information Science 21 (1): 21-48, 2007.

Many real and artificial entities in geographic space, such as transportation networks and trajectories of movement, are typically modeled as lines in geographic information systems. In a similar fashion, people also perceive such objects as lines and communicate about them accordingly as evidence from research on sketching habits suggests. To facilitate new modalities like sketching that rely on the similarity among qualitative representations, oftentimes multi-resolution models are needed to allow comparisons between sketches and database scenes through successively increasing levels of detail. Within such a setting, topology alone is sufficient only for a coarse estimate of the spatial similarity between two scenes, whereas metric refinements may help extract finer details about the relative positioning and geometry between the objects. The 9-intersection is a topological model that distinguishes 33 relations between two lines based on the content invariant (empty-nonempty intersections) among boundaries, interiors, and exteriors of the lines. This paper extends the 9-intersection model by capturing metric details for line-line relations through splitting ratiosand closeness measures. Splitting ratios, which apply to the 9-intersection's non-empty values, are normalized values of lengths and areas of intersections. Closeness measures, which apply to the 9-intersection's empty values, are normalized distances between disjoint object parts. Both groups of measures are integrated into compact representations of topological relations, thereby addressing topological and metric properties of arbitrarily complex line-line relations.

SIE students participate in Graduate Research Exposition

Fri, 18 Apr 2008 10:55:00

The 10th Annual Graduate Research Exposition was held April 15-16, 2008, in the Buchanan Alumni House at the University of Maine. The Expo, which is organized by UMaine’s Graduate Student Government, is an opportunity for graduate students to showcase academic excellence and creative achievement. Graduate students from the Department of Spatial Information Science and Engineering with poster or oral presentations at the Expo were: David Almeida, Stacy Doore, Matthew Dube, Christopher Farah, Jixiang Jiang, Guang Jin, Qinghan Liang, Francois Neville, Arda Nural, Maria Vasardani, and Danqing Xiao. In addition, undergraduate senior Benjamin Weber participated in the Expo with a poster presentation. Three SIE students won prizes at the Expo. David Almeida won second prize and Francois Neville won third prize in the Engineering Posters category. And Maria Vasardani won second prize in the Engineering Talks category. Congratulations to David, Francois, and Maria and to all our SIE students for a job well done! (pictured, l. to r., Expo prize winners Francois Neville, David Almeida, Maria Vasardani)

Master's thesis defense by Kraig King

Mon, 07 Jan 2008 16:17:00

Kraig King successfully defended his M.S. thesis, "Linking Moving Object Databases with Ontologies," on November 27, 2007. His work investigates the supporting role of ontologies for supplementing the data contained by moving object databases. Details of the spatial representation as well as the sensed location of moving objects are frequently stored within a database schema. However, this knowledge lacks the semantic detail necessary for reasoning about characteristics that are specific to each object. Ontologies contribute semantic descriptions for moving objects and provide the foundation for discovering object similarities. These similarities can be drawn upon to extract additional details about the objects around us. The primary focus of the research is a framework for linking ontologies with databases. An ontology linking tool, implemented as a stand alone application, is introduced. A major benefit gained from this kind of linking is the augmentation of database knowledge and multi-granular perspectives that are provided by ontologies through the process of generalization. Kraig's advisor is Kathleen Stewart Hornsby.

Master's thesis defense by Kripa Joshi

Mon, 07 Jan 2008 16:10:00

Kripa Joshi successfully defended her M.S. thesis on November 26, 2007. Kripa's thesis, "Combining Geospatial and Temporal Ontologies," introduced a method for automatically combining a pair of ontologies using cross products. A geospatial ontology and a temporal ontology, both represented in Protégé, are used as example ontologies in this work. Computing the cross product of the geospatial and temporal ontologies gives a complete set of pair-wise combination of terms from the two ontologies. This offers researchers the benefit of using ontologies that are already existing and available, rather than building new ontologies for areas outside their scope of expertise. The resulting framework describes a geospatial domain over all possible temporal granularities, allowing one domain to be understood from the perspective of another. Kripa's advisor is Kathleen Stewart Hornsby and support for her research comes from the National Geospatial-Intelligence Agency.

Onsrud receives College's Ashley S. Campbell award

Mon, 07 Jan 2008 11:12:00

Professor Harlan J. Onsrud received the College of Engineering's Ashley S. Campbell award at the college's annual Edward T. Bryant Recognition Banquet held November 2, 2007 in Orono. The Ashley S. Campbell award was established in 1979. The purpose of the award is to give recognition to a faculty member who has, by his or her activities, achievements, and scholarship brought distinction to the education of engineering students. Congratulations to Harlan for being nominated for this prestigious award! (pictured: Professor Mike Worboys, Department Chair (l.) handing the award to Professor Onsrud (r.))

Two tenure-track positions in ubiquitous spatial computing

Tue, 21 Aug 2007 09:48:50

The Department of Spatial Information Science and Engineering and National Center for Geographic Information and Analysis (NCGIA) at the University of Maine are seeking applications for two academic-year, tenure-track Assistant or Associate Professor level positions with research foci in ubiquitous spatial computing starting in January 2008. Further information may be found at http://www.spatial.maine.edu/~tenuretrack/.

Geo-Mobile Query-by-Sketch

Thu, 28 Dec 2006 13:18:00

David Caduff and Max J. Egenhofer, Geo-Mobile Query-by-Sketch, International Journal of Web Engineering and Technology, 3 (2): 157-175, 2007.

The advent of wireless technology, such as cellphones, PDAs, tablet PCs, and sub-notebooks, allows tranferring portions of traditional desktop-based GIS technology to mobile environments. This paper introduces Geo-Mobile Query-by-Sketch, a sketch-based spatial querying system for mobile GIS environment that combines techniques for spatial querying with mobile technologies. The system implements and adaptive client-server architecture, which copes with restrictions of mobile environments, such as fluctuating bandwidth and fre quent disconnections. The core concept analyzed is the mobile sketch, a multi-representation data structure of a sketched scene, which enables an adaption strategy that is tialored to the available transmission rates. We analyze the transmission cost of Geo-Mobile Query-by-Sketch and develop a protocol that optimizes the adaption level in order to guarantee quality of service.

The Head-Body-Tail Intersection for Spatial Relations Between Directed Line Segments

Thu, 28 Sep 2006 08:53:00

Yohei Kurata and Max J. Egenhofer, The Head-Body-Tail Intersection for Spatial Relations Between Directed Line Segments, in: M. Raubal, H. Miller, A. Frank, and M. Goodchild (eds.) GIScience 2006—4th International Conference on Geographic Information Science, Lecture Notes in Computer Science, Vol. 4197, pp. 269-286.

Abstract

Directed line segments are fundamental geometric elements used to model through their spatial relations such concepts as divergence, confluence, and interference. A new model is developed that captures spatial relations between pairs of directed line segments through the intersections of the segments' heads, bodies, and tails. This head-body-tail intersection identifies 68 classes of topological relations between two directed line segments highlighting two equal-sized subsets of corresponding relations that differ only by their empty and non-empty body-body intersections. The relations' conceptual neighborhood graph takes the shape of a torus inside a torus, one for each subset. Another 12 classes of topological relations are distinguished if the segments' exteriors are considered as well, lining up such that their conceptual neighborhood graph forms another torus that contains the other two tori. These conceptual neighborhoods as well as the relations' composition table enable spatial inferences and similarity assessments in a consistent and reasoned manner.

Changes in Topological Relations when Splitting and Merging Regions

Fri, 08 Sep 2006 00:00:00

M. Egenhofer and D. Wilmsen, Changes in Topological Relations with Splitting and Merging Regions, in: A. Riedl, W. Kainz, and G. Elmes (eds.), Progress in Spatial Data Handling -- 12th International Symposium on Spatial Data Handling, Springer, pp. 339-352.

Abstract

This paper addresses changes in topological relations as they occur when splitting a region into two. It derives systematically what qualitative inferences can be made about binary topological relations when one region is cut into two pieces. The new insights about the possible topological relations obtained after splitting regions form a foundation for high-level spatio-temporal reasoning without explicit geometric information about each object’s shapes, as well as for transactions in spatio-temporal databases that want to enforce consistency constraints.

GeoSpatial Semantics--First International Conference, GeoS 2005

Wed, 09 Nov 2005 00:00:00

A. Rodríguez, I. Cruz, M. Egenhofer, and S. Levashkin (editors), GeoSpatial Semantics--First International Conference, GeoS 2005, Lecture Notes in Computer Science, Vol. 3799, Spinger, New York, 2005.

This book contains the fully refereed papers of the First International Symposium on Geospatial Semantics, GeoS 2005, to be held in Mexico City, Mexico in November 2005.

Ontology-Driven Map Generalization

Wed, 12 Oct 2005 00:00:00

L. Kulik, M. Duckham, and M. Egenhofer, Ontology-Driven Map Generalization Journal of Visual Languages and Computing 16 (3): 245-267, 2005.

Abstract

Different users of geospatial information have different requirements of that information. Matching information to users' requirements demands an understanding of the ontological aspects of geospatial data. In this paper, we present an ontology-driven map generalization algorithm, called DMin, that can be tailored to particular users and users' tasks. The level of detail in a generated map is automatically adapted by DMin according to the semantics of the features represented. The DMin algorithm is based on a weighting function that has two components: (1) a geometric component that differs from previous approaches to map generalization in that no fixed threshold values are needed to parameterize the generalization process and (2) a semantic component that considers the relevance of map features to the user. The flexibility of DMin is demonstrated using the example of a transportation network.

Spherical Topological Relations

Thu, 01 Sep 2005 00:00:00

M. Egenhofer, Spherical Topological Relations, Journal on Data Semantics III: 25-49, 2005.

Abstract

Analysis of global geographic phenomena requires non-planar models. In the past, models for topological relations have focused either on a two-dimensional or a three-dimensional space. When applied to the surface of a sphere, however, neither of the two models suffices. For the two-dimensional planar case, the eight binary topological relations between spatial regions are well known from the 9-intersection model. This paper systematically develops the binary topological relations that can be realized on the surface of a sphere. Between two regions on the sphere there are three binary relations that cannot be realized in the plane. These relations complete the conceptual neighborhood graph of the eight planar topological relations in a regular fashion, providing evidence for a regularity of the underlying mathematical model. The analysis of the algebraic compositions of spherical topological relations indicates that spherical topological reasoning often provides fewer ambiguities than planar topological reasoning. Finally, a comparison with the relations that can be realized for one-dimensional, ordered cycles draws parallels to the spherical topological relations.

Advances in Spatial and Temporal Databases--9th International Symposium, SSTD 2005

Mon, 22 Aug 2005 00:00:00

C. Bauzer Medeiros, M. Egenhofer, and E. Bertino (editors), Advances in Spatial and Temporal Databases--Nineth International Symposium, SSTD 2005, Lecture Notes in Computer Science, Vol. 3633, Spinger, New York, 2005.

This book contains the fully refereed papers of the 9th International Symposium on Spatial and Temporal Databases, SSTD 2005, held in Angra dos Reis, Brazil in August 2005.