Spatial analysis vector models october, 2010 joseph ferreira, jr. Lakes would typically be stored in a polygon poly vector gis file, called, e. Visual analysis methods vam, data storage vector data storage, attribute data storage, an overview of the data manipulation and analysis. Vector data can have quality issues such as undershoots, overshoots and slivers which you need to be aware of. 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. Vector model vector maps are point, segment, or polygon maps. Digitising is the process of creating digital vector data by drawing it in a gis application. A forest area stand is usually delineated and stored in a separate poly gis file, often called fri. You can use the notes editor tool to view, add, delete, or modify notes associated with individual features. It distinguishes between primary direct measurement and secondary derivation from other sources data capture for both raster and vector data types.
Spatial data entered into a gis always fits into one of two main data structures, being either raster or vector data. Vector data is arguably the most common kind of data you will find in the daily use of gis. Worboys, 1997 other definitions of gis a container of maps in digital form. It is often necessary to change between file formats, even if they are both raster, or both vector, to make data sets useable together. Is it possible to manipulate the vector layers using the information from the grid layer and save as correctly located shp files. Jun 06, 2017 data models in geographical information system gis 1. Handbook on geographic information systems and digital mapping. Raster data is made up of pixels or cells, and each pixel has an associated value. Integrated analysis of the spatial and attribute data. An introduction to geographical information systems gis what is a geographical information system.
Vector data models use points and their associated x, y coordinate pairs to represent the. The elements in a vector based gis are then the dbms data base management system for the attributes and the system that manages the topological data. Within a gis, the uses of raster data fall under four main categories. Quantum gis, grass gis, saga gis, gdal tools, mapserver, openev, udig, and more. They are less suitable for a number of gis operations, especially those dealing with map overlaying. Create, edit and work with shape files vector data.
It is fairly easy to exchange information from within these raster formats. Handbook on geographic information systems and digital mapping united nations new york, 2000 ii note. Vector data models structures vector data models can be structured many different ways. Vector processing in a gis site selection exercise using vector data. Vector data can be used for spatial analysis in a gis application, for example to find the nearest hospital to a school. Geographical information systems gis introduction geographical information system gis is a technology that provides the means to collect and use geographic data to assist in the development of agriculture.
Introduction to gis and spatial data vector and raster comparison vector raster compact data structure for homogenous areas. Introduction to basic gis and spatial analysis using qgis. According with the characteristics of this data model, geographic objects are explicitly represented and, within the spatial characteristics, the thematic aspects are associated. You have been asked to prepare a lesson that explains to beginning gis users the difference between vector and raster data. Here you can download the free lecture notes of remote sensing and gis pdf notes rs and gis pdf notes materials with multiple file links to download. Geographic information systems modules spring 2016 center for digital scholarship university of notre dame matthew l. Data issues in vector processing world is complex but data represents a simplified version in vector data, objects are represented as points, lines and polygons to get data into a gis, two procedures are used, selection and representation. I receive a lot of pdf maps vector, image, with georeference and without and i am having to convert them to an image file before i can add them to arcmap and georeference. A digital map is generally of much greater value than the same map printed on a paper as the. A gis geographic information system is a powerful tool used for computerized mapping and spatial analysis. Download vector layers and readytogo gis projects based on osm esri shape, geodatabase, geojson, pdf, csv, tab, pbf, xml, sql formats for qgis. Can overlay displays easily can easily manipulate data table can have many variables linked to one geographic file better suited for map output a simple data structure. However, the distinction between vector and raster data types is not unique to gis.
Brief introduction to grass gis temporal framework which contains a lot of general notes about spatiotemporal data data display and visualization outline. However no map projection data was saved to the pdf. Quantum gis or qgis, or quantum geographic information system is a free, open source geographic information system. These methods are indispensable for understanding the basic quantitative and qualitative trends of a dataset. Thanks for contributing an answer to geographic information systems stack exchange.
Data, created by dgmm, downloadable also from our im toolkit link provided below. Chapter 8 spatial operations and vector overlays intro. This is a comprehensive tutorials on creating, editing and working with shape filesvector data in arc map. It is one of the two main types of gis data models, the other being the raster data model. A quick guide overview quantum gis, which is often called qgis, is an open source gis desktop application. This diagram shows how gis applications deal with vector data. An introduction to geographical information systems gis. Quantum gis tutorial for science on a sphere written by audrey randall. It describes geographic data in terms of points, that may be connected into lines and polygons.
Discuss components of spatial data explain differences between the raster and vector spatial data models. Within the spatial referenced data group, the gis data can be further classified into two different types. Every object in a vector dataset is called a feature, and is associated with data that describes that feature. These pages are a compilation of lecture notes for my introduction to gis and spatial analysis course es214.
Most of the output maps for raster data could not be used by cartographers because of its inaccuracy. Lecture 2 introduction to gis based on lecture notes of. In this presentation, we will introduce types of geographic data in order to define them and differentiate between them. Includes province names, related pcodes and population of syrian individuals. It provides a way for nonprogrammers to create maps using gis information. Most of the maps are obtained by digitizing or by importing them. A computerized tool for solving geographic problems. 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. A geographical information system is a collection of spatially referenced data i. The image of a noncontiguous maps will not be as accurate as vector data map would be due to the distortion created by the different cell sizes notes paul bolstad 2008. Zhongrhen peng from fall 2003 administrative notes. Notes displayed in readonly mode originate from the workspace of the layers in the table of contents window. Import vector data to qgis from pdf and apply georeference. I have a pdf created by mapinfo, it contains multiple layers of vector data that i can open as separate vector layers in qgis.
Lecture 1 intro to gis and gis vector and raster data models. Discuss components of spatial data centers for disease. In some gis packages, the dbms is based in an existing software, i. Handbook on geographic information systems and digital. 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. Introduction to gis workbook university of maryland libraries. They are ordered in such a way to follow the course outline, but most pages can be read in any desirable order. Vector data models demo 2 is intended to introduce you to the display and manipulation of vector data in the arcmap component of arcgis. Comparing to arcgis, qgis can be installed on various operating systems, such as windows, mac os x, linux ubuntu, and unix, while arcgis only has windows version. For this seminar we will be using arcgis desktop 10, the newest version of a popular gis software produced by esri. A gis is designed for the collection storage, and analysis of objects and phenomena where geographic location is an important characteristic or critical to the analysis. A vector based gis is defined by the vectorial representation of its geographic data.
In contrast to the raster data model is the vector data model. The vector data model is a strategy for describing distinct features in a gis. Landcover data is produced by assigning each pixel in a landsat thematic mapper image to one of 16 landcover classes using a procedure known as unsupervised classification. What is the difference between vector and raster data models. In gis, vector and raster are two different ways of representing spatial data. Whats the difference between gis spatial data types. Introduction to gis basics, data, analysis case studies.
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. One of the most important topic in gis geographic information system, which is types of data. Index introduction components of gis data types in gis data representation raster data model vector data model differences between raster and vector triangulated irregular network tin digital elevation model dem conclusion reference. A representation of the world using vertices or points, connected vertices or lines, and closed connected vertices or polygons. A small pond might be stored as part of a wetlands gis file. Change data symbology change display properties set relative paths add layers to features select data measure distances use raster create map layouts to print add legends, titles, north arrows print a map to a pdf data for this exercise are located in the l1 zip file, available from the class websites. Vector maps require less disk storage space and are suitable for creating high quality outputs. In vector data, the basic units of spatial information are points, lines arcs and polygons. We will examine two of the more common data structures here vector data model. Computer tool for managing geographic feature location data and data related to those features. Every house, every tree, every city has its own unique latitude and longitude coordinates. They are the result of more than 20 years involvement in gis and spatial data handling.
Taking the raster data model first, it represents space as a continuous field consisting of squares called pixels of a standard size, like the picture on a computer monitor or tv screen. Remote sensing and gis notes pdf rs and gis notes pdf book starts with the topics principle and types of aerial photographs. A gis provides functionality to capture, store, query, analyze, display and output geographic information. Complex data structures means that phenomenonologically recognizable combination of several vector polygon maps through overlay creates difficulties simulation is difficult because each unit has a different topological form display and plotting can be expensive, particularly for. Divides space into discrete features, usually points, lines or polygons. In this model, space is not quantized into discrete grid cells like the raster model. Nsdi national spatial data infrastructure pdf portable document format pes post enumeration survey. Vector representation vector representation of data in the vector based model figure 4, geospatial data is represented in the form of coordinates. Chapter 9 gis data collection 117 gis data collection. Adding, deleting, or modifying notes requires that you start editing. A common use of raster data in a gis is as a background display for other feature layers.
It was once referred to as sieve mapping by land use planners who combined different layerseach mapped onto separate transparenciesto isolate or eliminate areas that did or did not meet a set of criteria map overlay refers to a group of procedures and techniques. The objective of this section is to understand how vector data models are implemented in gis applications. In chapter 6 data characteristics and visualization, we discussed different ways to query, classify, and summarize information in attribute tables. This lecture notes are the authors view on what the basic scientific principles of gis are that everybody should know who wants to use and understand todays geographic information system software. Jun 06, 2017 contents introduction spatial data models data representation vector data model types of vector data models advantages and disadvantages conclusion reference 3. While the structure of raster data is simple, it is exceptionally useful for a wide range of applications. What is the difference between vector and raster data. Vector data analysis zvector data analysis uses the geometric objects of point, line, and polygon. They are the result of more than 20 years involvement in gis and spatial data.
1532 1627 283 884 515 881 631 1651 441 915 927 1589 1112 892 1139 1597 221 903 1604 1011 820 1412 1017 902 955 1091 534 668 1356 1022 373 727 608 704 723 827 801 250 775 272 1072 153