In gis, vector and raster are two different ways of representing spatial data. There are several advantages and disadvantages for using either the vector or raster data model to store spatial data. It is often difficult to compare or rate gis software that use different data models. A short and sweet description of the two data models and how they handle object versus discrete phenomena.
What is the difference between vector and raster data. The raster data model is widely used by nongis technologies such as digital cameraspictures and lcd monitors. A raster graphic, such as a gif or jpeg, is an array of pixels of various colors, which together form an image. The raster data model, along with the vector data model, is one of the earliest and most widely. Oct 14, 2019 however, pdfs will primarily only be editable by adobe products. This value can be interpreted to mean several different things. Raster giss and vector giss operate differently and are used to address different types of geographical problems. Vector data represent features as discrete points, lines, and polygons. The raster vs vector gis question is rarely one you need to worry about. Raster models are useful for storing data that varies continuously, as in an aerial photograph, a satellite image, a surface of chemical concentrations, or an elevation surface. Vector data model representations of the real world source. Other programs will be able to handle pdf files but mainly only if the information on a pdf file is vector data. As well, a typical gis process involves moving backandforth between the two models.
There are many analysis that make use of both data models i. For example, you can process data through a geoprocessing model to create a raster dataset that maps suitability for a specific activity. The main difference between raster and vector is how they create the final image. Lecture 1 intro to gis and gis vector and raster data models. 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.
Raster and vector are two methods of creating and storing digital images. The vector model uses points and line segments to identify locations on the earth while the raster model uses a series of cells to represent locations on the earth. Data structure vector data represents discrete geographic entities and tends to. Mar 01, 2019 the main difference between raster and vector data is that the raster data represents data as a cell or a grid matrix while vector data represents data using sequential points or vertices. The spatial resolution of a raster dataset represents a measure of the accuracy or detail of the displayed information. Besides increased processing requirements this may introduce controversy over data due to generalization and choice of inappropriate cell size. Instead, vector graphics are comprised of vertices and paths. Composite files contain both raster and vector information. Jan 20, 2018 vector models are useful for storing data that has discrete boundaries, such as country borders, land parcels, and streets. The raster data model is a widely used method of storing geographic data. When should we use raster and when should we use vector. It unifies the storage of multiple raster data types, including satellite imagery, gridded data e. In general, the vector data model is used to represent the former and the raster data model to represent the latter.
Demers 1 the nature of geographic data most features or phenomena occur as either. Two primary data models are available to complete this task. Being comfortable with the ins and outs of both formats and how they translate when exported is an essential skill for every designer. Jan 14, 2011 since most input data is in vector form, data must undergo vector to raster conversion. Sections describing raster data models, tin data models, and data structure then follow. Maidment, introduction to spatial hydrology esri campus continuous surfaces can be represented using the grid or raster data model in which a mesh of square cells is laid over the landscape and the value of the variable defined for each cell. Raster and vector data and data structures web pages marshall.
Raster images are made up of pixels, while vector images are formed by mathematical curves and paths. Raster data are derived from a gridbased system of contiguous cells containing specific attribute information. Data can be represented at its original resolution and form without generalization. Mrr is a completely new raster data format that reimagines how raster data is stored and what data can be stored as a raster.
Different types of raster models or raster representations. Remember that rasters are rectangular, check that they do. Measured real values an be integer or floatingpoint decimal values. The raster data model jackson school of geosciences. Difficult to resolve fine details little to no variation of values of large area better captured by vector data. Apr, 2016 a short and sweet description of the two data models and how they handle object versus discrete phenomena. Simplifying slightly, a digital photograph is an example of a raster. As models, they each have strengths and weaknesses. Raster data represent the landscape as a rectangular matrix of square cells. But what is the difference between raster and vector data. Below is an example of a classified raster dataset showing land use. Vector data models use points and their associated x, y coordinate pairs to represent the vertices of spatial features, much as if they were being drawn on a map by hand aronoff 1989. In contrast, raster uses a grid with each element in the.
When it comes to the difference between raster pdf file and vector pdf file,we may easily know the point is the difference between raster and vector. The three basic symbol types for vector data are points, lines and polygons areas. However, it is possible to represent the data present in the study region in different ways as shown below. Geographic information system gis is a computerbased tool or technology to manage, analyze and display geographically referenced information. Sometimes you dont have the choice of storing your data as a raster. Raster and vector data structures are two alternate meth ods for representing spatial phenomena. In the old days, the dinosaur days of gis, there was actually raster gis software and vector gis software. What is the difference between vector and raster data models. We will examine two of the more common data structures here. Spatial analysis ii raster models 26 october 2005 joseph ferreira raster vs. The gis spatial data model university of washington.
The simplest vector data structure is called the spaghetti data model a data model in which each point, line, andor polygon feature is represented as a string of x, y coordinate pairs with no inherent structure. Raster data consists of rows and columns of cells or pixels. However, there are many other features such as points and measurements such as rainfall that could be stored as. The main difference between vector and raster graphics is that raster graphics are composed of pixels, while vector graphics are composed of paths. Types of raster data model advantages, disadvantages just. Spatial data types its not always straightforward which spatial data type you should use for your maps. In this unit, we will discuss the basic concepts of raster and vector data models in gis. Depending on the type of problem that needs to be solved, the type of maps that need to be made, and the data source, either raster or vector, or a combination of the two can be used. Historically, it has generally been accepted that raster calculations were faster, while vector methods gave higher accuracy kennedy and meyers, 1977. Each of these models has its own advantages and disadvantages. Raster data models 9182018 geo327g386g, ut austin 3 geo327g386g. Apr 15, 2016 since most input data is in vector form, data must undergo vector to raster conversion. The model most commonly takes the form of a gridlike structure that.
The model most commonly takes the form of a gridlike structure that holds values at regularly spaced intervals over the. The majority of output maps from gridcell systems do not conform to highquality cartographic needs. Vector models are useful for storing data that has discrete boundaries, such as country borders, land parcels, and streets. Difference between raster and vector difference between. What is the difference between raster and vector data. In this model, space is not quantized into discrete grid cells like the raster model. Tin data model and comparisons with raster duration. Thematic maps can also result from geoprocessing operations that combine data from various sources, such as vector, raster, and terrain data. Vector data model represents phenomena in terms of the spatial primitives, or components, consisting of point, line, polygon, surfaces and volumes. Mar 11, 2020 note that raster operations in arcmap are not covered on this years test but knowing the difference between raster and vector models is covered feedback on homework and labs rida slides shown in lecture. Geopdf a pdf that can be georeferenced you need to download a plugin for adobe. In the end, it really comes down to the way in which the cartographer conceptualizes the feature in their map. So how do we make raster and vector clear seems important.
Pdf the raster data model is a widely used method of storing geographic data. Sep 03, 2016 raster data model and comparisons with vector. They are more common in general such as jpg, gif, png, and are widely used on the web. Find out more on the spatial data models commonly used. However, the lines od separation are sometimes crossed. Vector uses a combination of primitive shapes like circles, lines, and curves in order to create the final image. Make sure any raster files you use contain enough data for the final print size. Instead, vector graphics are comprised of vertices. In contrast to the raster data model is the vector data model. Raster data models present information through a grid of cells. Raster vs vector gis gis university raster vs vector gis.
Raster is faster but vector is corrector esri support. Either way, you can load raster and vector data into the same map, you can actually, with a lot of these tools, be able to create a raster analysis from say vector points. Vector data models for gis vector model boundaries of spatial features our focus so far vector feature types. A comparison of vector and raster gis methods for calculating. Raster data is usually represented in the form of regular array of grids covering the study region or area of interest. Based on the georelational data model, an arcinfo coverage has two components. However, the distinction between vector and raster data types is not unique to gis. Vector data models can be structured many different ways. Unlike vector data models, which show geographic data through points, lines, or polygons, raster data is displays one value in each cell. Simple data structures overlay and combination of maps and remote sensed images easy some spatial analysis methods simple to perform simulation easy, because cells have the same size technology is cheap disadvantages of raster data structures. Continuous surfaces can be represented using the grid or raster data model in which a mesh of square cells is laid over the landscape and the value of the.
Raster data models and comparisons with vector youtube. Raster data is made up of pixels or cells, and each pixel has an associated value. What is the difference between raster pdf file and vector. Raster images in pdf files, for them to be readily editable, have to first be converted into vector images. While deciding whether to use a vector data model or raster data model in your work it entirely depends on the data you have as input and what your goals are for displaying or analyzing the data.
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