Introduction gis does not store a map in any conventional sense, nor it stores a particular image or view of geographic area. Presentation pdf available august 2017 with 7,090 reads how we measure reads a read is counted each time someone views a publication summary such as the title. There are two primary types of spatial data models. The data base concept is central to a gis and is the main difference between a gis and drafting or computer mapping systems, which can produce only good graphic output. Data model representations of the real world source. Lecture 1 intro to gis and gis vector and raster data models. For example, a table is a very simple example of a data model, and in the way in which tables are often used in gis, the rows of the table correspond to a group or class of realworld features, such as counties, lakes, or trees, and the columns corre.
Data models are a set of rules andor constructs used to describe and represent aspects of the real world in a computer. Data models in geographic information systems citeseerx. A data model in gis is a mathematical construct for representing geographic objects or surfaces as data. As database management systems dbms represent the dominant technology in gis, we would like to briefly. In vector data, the basic units of spatial information are points, lines arcs and polygons. Vector data represents features as discrete points, lines, and polygons. In gis, a set of data models are used for various applications. A data model is a way of defining and representing real world surfaces and characteristics in gis. Geographic information system gis is defined as an information system that is used to input, store, retrieve, manipulate, analyze and output geographically referenced data or geospatial data. The attribute data are linked to the corresponding cartographic objects in the spatial part of the gis database. Data a collection of facts or figures that pertain to places, people, things, events and concepts. Two primary data models are available to complete this task.
Spatial databases and gis karl neumann, sarah tauscher ifis tu braunschweig. Many gis data models implement the defined by 21, 22. Geographic information system, data model, spatial database, accuracy. In gis, there are also locational data x,y,z coordinates representing positions on the surface of the earth.
Discuss components of spatial data centers for disease. The data model represents a set of guidelines to convert the real world called entity to the digitally and logically represented spatial objects consisting of the attributes and geometry. Gis data represents realworld objects such as roads, land use, elevation with digital data. For example, a table is a very simple example of a data model, and in the way in which tables are often used in gis, the rows of the table correspond to a group or class of. Information data structured, formatted, converted and. In some gis packages, the dbms is based in an existing software, i. Instead, a gis stores the data from which we can draw a desired view to suit a particular purpose known as geographic data. Two data models commonly used to represent spatial data in gis are the raster and vector data models within the vector data model, a representation of the world is created using lines, points, and polygons. Raster and vector data model in gis there are two essential methods used to store information in a geographic information system gis for both reflections. One of the most important formats is vector data model which holds. These are vector data model and raster data models. Keys, labels, or other indices are used so that the.
Geospatial data models geospatial science at humboldt state. The raster data model is a widely used method of storing geographic data. The attributes are managed by thematic or semantic structure while the geometry is. In essence, gis data models allow the user to create a representation of how the world looks. Vector data is focused on modeling discrete features with precise shapes and boundaries. Introduction to gis basics, data, analysis case studies. Geographic data modeling uc santa barbara geography. A later section of the chapter provides a more extended discussion of. Chapter 1 gis and modeling overview uc santa barbara geography.
Conclusion geographic information system is a computer system for capturing, storing, checking, and displaying data related to positions on earths surface. Data are usually represented by numerical values, alphanumeric characters, logical values, etc. The model most commonly takes the form of a gridlike structure that holds values at regularly spaced intervals over the. Gis does not store a map in any conventional sense, nor it stores a. Pdf data models are a set of rules andor constructs used to describe and represent aspects of the real world in a computer. The data model data model is a conceptual description mental model of how spatial data are organized for use by the gis. Full integration of geodata in gis modelling in gis models complexity according to miller e.
The two basic data models of gis are raster and vector. In order to visualize natural phenomena, one must first determine how to best represent geographic space. Pdf spatial data can be manipulated in different formats and patterns. All contemporary geographic information system incorporates a data base management system. In a gis, an entity is any fact that can be localised spatially.730 146 1102 1170 1188 769 687 1038 83 1543 364 151 974 1275 690 1210 1608 1591 775 1447 1168 1323 438 205 349 486 15 904 441 197 125 14 1345