Piotr jankowski, former professor in department of geography at ui objective the purpose of this lecture is to provide an introduction to gis and give an overview of basic theoretical and technical concepts in gis. In gis, vector and raster are two different ways of representing spatial data. The basic framework of the model is to describe each needed feature by its geometry location and shape and attributes also known as properties or characteristics. How the data is stored in the database, the applications that access it, and the client and server hardware configurations are all key factors to a successful multiuser geographic information system gis. Lecture 1 intro to gis and gis vector and raster data models. Data volume and redundancy dense grid of data involves large memory requirements and computer power. Each of these models has its own advantages and disadvantages. As sample data, a usgs quad sheet and one type of each shapefile are provided. Spatial data introduction it uses points and their x,ycoordinates to geographical. Most advanced gis software can handle both models and even convert data.
Every house, every tree, every city has its own unique latitude and longitude coordinates. Vector data models use points and their associated x, y coordinate pairs to represent the. Discuss components of spatial data centers for disease. In this current article, we will discuss in detail about what is vector data model, how data is represented using vector data model and different types of vector data structures. Gis data represents realworld objects such as roads, land use, elevation with digital data.
This chapter discusses the concepts of spatial data models, especially the model that is. However, the distinction between vector and raster data types is not unique to gis. One of the most important formats is vector data model which holds topological relationships between geographic features. Points, nodes and vertices define points, line, and polygon features in a vector data model. Thematic maps can also result from geoprocessing operations that combine data from various sources, such as vector, raster, and terrain data.
Difference between vector and raster data model vector data model. Spatial data can be manipulated in different formats and patterns. A table consists of records rows representing individual features, fields columns. The data model a logical data model is how data are organized for use by the gis. There are two essential methods used to store information in a geographic information system gis for both reflections. The focus of this paper is on an eventbased spatiotemporal data model with integrated vector and raster data. Vector representation vector representation of data in the vector based model figure 4, geospatial data is represented in the form of coordinates. The georelational data model has been used for years in gis. Understanding of vector data models as used in gis. Research and implementation of eventbased spatiotemporal.
The vector data model is based on the assumption that the earths. In this model, space is not quantized into discrete grid cells like the raster model. Spatial data models geographic information system gis. Two common data models used to represent geographic data are the vector data model and the raster data model. Practice exam 1 geospatial core technical knowledge examr the geospatial core technical knowledge exam is administered twice each year, and an individual must score at least 75% correct. Vector data can be used for spatial analysis in a gis. In contrast to the raster data model is the vector data model. In vector data, the basic units of spatial information are points, lines arcs and polygons. Vector data can have quality issues such as undershoots, overshoots and slivers which you need to be aware of. Suitability modeling workflow using arcgis prolesson 1. Practice exam 1 geospatial core technical knowledge examr. Giss have traditionally used either raster or vector for maps. An eventbased spatiotemporal data model or eventoriented approach is either rasterbased or vector based and thus the models fail to handle evolving geographical phenomena and spatiotemporal objects simultaneously. Raster model vector model points, lines, polygons features and maps a gis.
Yiping fang is an assistant professor of urban studies and planning at portland state university. Gis has five layers, which are spatial reference framework, spatial data model, spatial data acquisition systems, spatial data. What kind of applications would each be most suited to. Conclusion geographic information system is a computer system for capturing, storing, checking, and displaying data related to positions on earths surface. Exploring and deriving data download the data in this lesson, you will identify and derive criteria for the habitat submodel, one of the three submodels comprising the bobcat suitability model. Creating vector data in arcgis in this workshop, you will learn how to derive vector features from a raster dataset. As such, vector data tend to define centers and edges of features. The vector data model is a strategy for describing distinct features in a gis.
Whats the difference between gis spatial data types. The old gis adage raster is faster, but vector is corrector comes from the two different fundamental gis models. What is the difference between raster and vector data. Raster data models present information through a grid of cells raster grids are usually made up of square or rectangular cells. What is the difference between vector and raster data. The topographic maps and geographical information system gis data provided in the national map are pregenerated into downloadable products often available in multiple formats. Download vector layers and readytogo gis projects based on osm esri shape, geodatabase, geojson, pdf, csv, tab, pbf, xml, sql formats for. 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. Each model has its unique way in representing the data. There are two conceptually different data models available for storing gis databases. Gis and modeling overview the term modeling is used in several different contexts in the world of gis, so it would be wise to start with an effort to clarify its meaning, at least in the context of this book. Lecture 2 introduction to gis based on lecture notes of. The two basic data models of gis are raster and vector. Vector data are composed of points, polylines, and polygons.
Vector data use x and y coordinates to define the locations of points, lines, and areas polygons that correspond to map features such as fire hydrants, trails, and parcels. The objective of this section is to understand how vector data models are implemented in gis applications. A table consists of records rows representing individual features, fields columns representing a particular theme attribute describing the feature, and values an intersection between a record and a field. Introduction to geographic information systems 19,552 views. Vector data model attributes in gis vector files attributes are, in a simple form, stored in tables databases. Successfully implementing a gis with arcinfo and arcsde starts with a good data model. Vector data provide a way to represent real world features within the gis environment.
For example, you can process data through a geoprocessing model. Vector representation of data in the vector based model, geospatial data is represented in the form of coordinates. Vector data is comprised of lines or arcs, defined by beginning and end points, which meet at nodes. Maps and gis data are available for digital download. Her research and teaching examines spatial structures from social sciences perspective. In a gis, geoobjects are represented either as vector or raster spatial data models. The third module is geographic information system gis, which is one of the four disciplines for spatial data science. Raster data models and comparisons with vector youtube.
The georelational model is the fundamental data model used in coverages. Unlike vector data models, which show geographic data through points, lines, or polygons, raster data. The old gis adage raster is faster but vector is corrector comes from the two different fundamental gis models. In vector data, the basic units of spatial information are points, lines and polygons. It is one of the two main types of gis data models, the other being the raster data model. The raster data model, along with the vector data model, is one of the earliest and most wide ly used data models within geographic information systems tomlin, 1990. Download vector layers and readytogo gis projects based on osm esri shape, geodatabase, geojson, pdf, csv, tab, pbf, xml, sql formats for qgis. List advantages and disadvantages of vector and raster data for gis. The advantages and disadvantages of vector and raster data. Vector is a data structure, used to store spatial data. The vector model uses points and line segments to identify locations on the earth while the raster model.
154 1020 1210 1189 1088 621 581 54 742 1527 1476 594 368 947 736 878 769 98 1216 1029 689 411 1039 1057 28 1388 376 540 881 913 528