Augmenting a Conceptual Model withGeospatiotemporal AnnotationsVijay Khatri, Member, IEEE, Sudha Ram, Member, IEEE, andRichard T. Snodgrass, Senior Member, IEEEAbstract—While many real-world applications need to organize data based on space (e.g., geology, geomarketing, environmentalmodeling) and/or time (e.g., accounting, inventory management, personnel management), existing conventional conceptual models donot provide a straightforward mechanism to explicitly capture the associated spatial and temporal semantics. As a result, it is left todatabase designers to discover, design, and implement—on an ad hoc basis—the temporal and spatial concepts that they need. Wepropose an annotation-based approach that allows a database designer to focus first on nontemporal and nongeospatial aspects (i.e.,“what”) of the application and, subsequently, augment the conceptual schema with geospatiotemporal annotations (i.e., “when” and“where”). Via annotations, we enable a supplementary level of abstraction that succinctly encapsulates the geospatiotemporal datasemantics and naturally extends the semantics of a conventional conceptual model. An overarching assumption in conceptualmodeling has always been that expressiveness and formality need to be balanced with simplicity. We posit that our formally definedannotation-based approach is not only expressive, but also straightforward to understand and implement.Index Terms—Data semantics, database design, semantic model, geospatial databases, temporal databases.æ1INTRODUCTIONMANY real-world georeferenced (e.g., land informationsystems, environmental modeling, transportationplanning, geomarketing, geology, archaeology) and time-varying (e.g., accounting, portfolio management, personnelmanagement, inventory management) applications need toorganize data based on space and/or time. Underlyingthese applications are temporal and/or geospatial data,collectively referred to as geospatiotemporal data. Conceptualdatabase design is widely recognized as an important stepin the development of database applications [1], [3], [7]such as those listed above. During conceptual databasedesign, a conceptual model provides a notation and formal-ism that can be used to construct a high-level description ofthe real world—referred to as a conceptual schema—inde-pendent of implementation details. The data semanticsprovides a mapping from the conceptual schema to aspectsin the real world. However, conventional conceptualmodels [1], [3], [7] do not provide a straightforwardmechanism to explicitly capture the semantics related tospace and time. As a result, it is left to the databasedesigners to discover, design and implement—on an ad hocbasis—the temporal and spatial concepts that they need. Inthis paper, we present a methodical approach thataugments a conventional conceptual model using geospa-tiotemporal annotations.Many prior studies [10], [23] attribute project failures tolack of identifying real needs during conceptual design.One of the problems with developing geospatiotemporalapplications is that there is “a gulf between the richness ofknowledge structures in the application domains and therelative simplicity of the data model in which the structurescan be expressed” [33], which in turn impacts the ability toelicit the application requirements. Considering that geo-graphic data are finding their way into traditional applica-tions (e.g., insurance, retail, distribution), there is a need foran overall geospatiotemporal conceptual database designmethodology that can be integrated into conventionalconceptual design. Thus, it would be helpful to developan approach that is compatible with an existing general-purpose methodology [1], [3], [7].Our annotation-based approach divides geospatiotem-poral conceptual design into two steps: 1) elicit the currentreality of an application using a conventional conceptualmodel without considering the geospatial and temporal aspects(“what”) and, only then, 2) annotate the schema with thegeospatiotemporal semantics of the application (“when”and “where”). Rather than creating new constructs in aconceptual model, we use annotations to elicit the geospa-tiotemporal aspects of the application. Our annotation-based approach is generic and can be applied to anyconventional conceptual model [1], [3], [7] to transform thatmodel into a geospatiotemporal conceptual model. In thispaper, we apply our annotation-based approach to theUnifying Semantic Model (USM) [22]—an extended versionof the Entity-Relationship (ER) Model [3]—to propose thegeoSpatioTemporal Unifying Semantic Model (ST USM).We mention here the assumptions in this paper todelineate the scope of our work.1. Based on perception, space may be differentiated aslarge-scale and small-scale [17]. As with Mark andFrank [19], we construe large-scale space as equiva-lent to geographic space. In the following, we use the1324 IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEER ING, VOL. 16, NO. 11, NOVEMBER 2004. V. Khatri is with the Information Systems Department, Kelley School ofBusiness, Indiana University, 1309 East 10th Street, BU 572, Blooming-ton, IN 47405-1701. E-mail: [email protected].. S. Ram is with the Department of MIS, University of Arizona, 1130 E.Helen St., Tucson, AZ 85721-0108. E-mail: [email protected].. R.T. Snodgrass is with the Department of Computer Science, University ofArizona, 711 Gould Simpson, PO Box 210077, Tucson, AZ 85721-0077.E-mail: [email protected] received 10 Jan. 2002; revised 26 Aug. 2003; accepted 13 Oct.2003.For information on obtaining reprints of this article, please send e-mail to:[email protected], and reference IEEECS Log Number 115685.1041-4347/04/$20.00 ß 2004 IEEE Published by the IEEE Computer Societyterm space interchangeably to mean large-scale spaceor geographic space.2. According to Peuquet [21], absolute space is objectivesince it provides an immutable structure that ispurely geometric. On the other hand, relative space isan ordering relation between objects that determinestheir relative position. We concentrate on absoluterepresentations, which are typically employed indatabases.3. A database schema can evolve with time. Schemaversioning [24] is an important area of research;however, we do not focus on schema versioning.In summary, this paper focuses on establishing afoundation for capturing the geospatio temporal datasemantics during conceptual design and does not delveinto