Raster and vector are the two basic data structures for storing and manipulating images and graphics data on a computer. In this video, i have clearly shown the steps required to convert raster file into vector file in arc gis software. Vector data models will be described in the next section, including commonly found variants. Image via nataliako due to the abundance of pixels in a raster image, the file sizes can be substantial. In this post we are looking forward to see the list of vector data file formats in gis. Raster and vector are two very different but common data formats used to store geospatial data. Vector representation of data in the vector based model, geospatial data is represented in the form of coordinates. Raster processes are more commonly used because they can. Visual integrity is specialized in tools for vector conversion and will produce highquality, accurate drawings from vector pdf input.
Conclusion geographic information system is a computer system for capturing, storing, checking, and displaying data related to positions on earths surface. Pdf the raster data model is a widely used method of storing geographic data. When exporting to eps, pdf, or ai illustrator, sometimes the vector data gets exported as raster strips or bands. The main spatial data types are vectors and rasters. The two basic data models of gis are raster and vector. Topology expresses the spatial relationships between connecting or adjacent vector features points, polylines and polygons in a gis. 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.
Digitising is the process of creating digital vector data by drawing it in a gis application. Aug 16, 2017 this tutorial is about vector and raster data in gis that how to understand the difference between vector and raster data structures. Hope you will find this tutorial best for learning. Usually satellite or areal imagery is represented in raster data format. Mar 26, 2018 in gis, we require some data formats to express the geographical features, which mainly are of two types raster and vector data formats. A raster based gis can portray continuously varying data more effectively and can analyze multiple layers of data easily. To reproduce the image the computer reads each of these cell values one by one and applies them to the pixels on the screen. Rasters have grid cells while vectors are points, lines and polygons consisting of vertices. What is the difference between raster and vector data. Discuss components of spatial data centers for disease.
Gis data represents realworld objects such as roads, land use, elevation with digital data. In vector data, the basic units of spatial information are points, lines arcs and polygons. 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. Within a gis, the uses of raster data fall under four main categories. Vector data can be used for spatial analysis in a gis application, for example to. Any gis users who need a better spatial understanding of their vector or raster data can use arcgis spatial analyst. Vector data can have quality issues such as undershoots, overshoots and slivers which you need to be aware of. Raster model represents area covered by grid with usually equal. Lecture 2 introduction to gis based on lecture notes of dr. The major use of raster data involves storing map information as digital images, in which the cell values relate to the pixel colours of the image. The output image quality control is intended to resample raster data prior to printing or exporting the map.
While the structure of raster data is simple, it is exceptionally useful for a wide range of applications. Every house, every tree, every city has its own unique latitude and longitude coordinates. Raster data and vector data raster and vector are the two basic data structures for storing and manipulating images and graphics data on a computer. Raster data and vector data are two types of spatial data in gis.
Pdf data data vector data and raster data find, read and cite all the research you need on researchgate. From analyzing the optimal location for a new retail store to the location of the most. Whats the difference between gis spatial data types. Major gis and cad computer aided design software packages available today are primarily based on one of the two structures, either raster based or vector. The old gis adage raster is faster, but vector is corrector comes from the two different fundamental gis models. The types of analyses that can be performed on raster data vs. More valuable that raster in my opinion is vector data from pdfs. In vector data, the basic units of spatial information are points, lines and polygons. Instead, vector graphics are comprised of vertices and paths. Each of these units is composed simply as a series of one or more coordinate points, for example, a line is a collection of related points, and a polygon is a collection of related lines. Integrated with the geoprocessing framework, arcgis spatial analyst offers easy access to numerous functions in modelbuilder, a graphic modeling tool. 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.
Geographic information system gis is a computerbased tool or technology to manage, analyze and display geographically referenced information. High spatial variability is efficiently represented. Convert pdf to dxf using graphics package such as illustrator, try and eliminate any unnecessary data at this stage, and clean up the layers. For example, orthophotographs displayed underneath other layers provide the map user with confidence that map layers are spatially aligned and represent real. Raster data sets record a value for all points in the area covered which may require more storage space than representing data in a vector format that can store data only where needed. Vector representation vector representation of data in the vector based model figure 4, geospatial data is represented in the form of coordinates.
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. Aug 21, 2019 raster and vector are two very different but common data formats used to store geospatial data. Storing abstracted objects two primary methods for digital storage vector formats discretely ide nt ify shape coordinates raster formats assign square cells to real world entities. Introduction to gis and spatial data vector and raster comparison vector raster compact data structure for homogenous areas. Rasters are especially well suited for storing continuous data such as temperature and elevation values. Rasters are especially well suited for storing continuous data. Rasters as basemaps a common use of raster data in a gis is as a background display for other feature layers. Topological or topologybased data are useful for detecting and correcting digitising errors e. An illustration with higher dpi dots per inch or ppi pixels per inch will be larger in size and data, which can be worrisome when there are limits to image storage or restrictions on uploaded file sizes. For maps with raster data or transparent vector layers, adjusting this value can significantly reduce the amount of data being passed through the output pipeline and will reduce export times and file sizes. When using this option, some enhanced features, such as layouts and attributes, will no longer work. Integration of both vector and raster data is a common feature in a gis project. Gis packages can display raster and vector data simultaneously, and can convert from raster to vector data or from vector to raster data. 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.
The vector data model is a strategy for describing distinct features in a gis. Vector and raster data difference between raster and. In gis, we require some data formats to express the geographical features, which mainly are of two types raster and vector data formats. Both of these methods present data in their own format, with their own advantages and disadvantages. The compression scheme used to compress image or raster data in the output file. Converting between raster and vector formats allows you to make use of both raster and vector data when solving a gis problem, as well as using the various analysis methods unique to these two forms of geographic data. As such, vector data tend to define centers and edges of features. However, the distinction between vector and raster data types is not unique to gis.
A common use of raster data in a gis is as a background display for other feature layers. The model most commonly takes the form of a gridlike structure that holds values at regularly spaced intervals over the extent of the raster. Most gis software applications mainly focus on the usage and manipulation of vector geodatabases with added components to work with raster based geodatabases. Vector file sizes are usually smaller than raster data, which can be tens, hundreds or more times larger than vector data depending on resolution. Convert gis data gis software and tools convert shapefile shp to pdf a gis file is a format used as a norm for encoding geographical information into computer readable. 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. For example, orthophotographs displayed underneath other layers provide the map user with confidence that map layers are spatially aligned and represent real objects, as well as additional information. Each of these models has its own advantages and disadvantages. The gis spatial data model university of washington. The use of large cells to reduce data volumes structures can be lost and there can be a serious loss of information crude raster maps are considerably less beautiful than line maps network linkages are difficult to establish projection transformations are time consuming. The closely mimics the manual drafting process by representing map features discrete spatial objects as a set of lines which, in turn, are stores as a series.
This tutorial is about vector and raster data in gis that how to understand the difference between vector and raster data structures. Nov 26, 2017 there are two essential methods used to store information in a geographic information system gis for both reflections. Raster gis is relatively fast and you can perform a wide range of visualization and analysis that are not possible in a vector based system. In vector data, the basic units of spatial information are. For maps or layouts containing vector layers with a high density of vertices, this can drastically reduce the output file size. One of the strengths of the vector data model is that it can be used to render geographic features with great precision.
Also, to be included in the lesson is a basic explanation of a landcover. Available for download is a zip archive containing an esri grid and erdas. In the vector based model figure 4, geospatial data is represented in the form of coordinates. 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. When we come to depict any spatial data in gis, from physical assets and locations to realworld events and trends, there are two differing systems to display data. Discuss components of spatial data explain differences between the raster and vector spatial data models present common types of spatial data you may encounter and use introduce you to arccatalogas a means of organizing and managing your spatial data discuss best practices regarding the organization of spatial data, as. Raster data is comprised of evenly sized and spaced cells that represent a continuous surface, while. The raster datasets also provide beautiful hillshade relief for your map. Raster data also introduce a large set of data analysis functions to gis. Gis refers to those spatial information systems that are used for processing and analyzing geospatial data. It distinguishes between primary direct measurement and secondary derivation from other sources data capture for both raster and vector data types. There are certain types of symbols that are rendered as raster in output. Vector data model attributes in gis vector files attributes are, in a simple form, stored in tables databases.
Vector data is more compatible with relational database environments, where they can be part of a relational table as a normal column and processed using a multitude of operators. Elevation, as a continuous land field characteristic, is usually stored in a vector file for easier data management, but is more suitable to be represented by a raster data model. Natural earth data is number 1 on the list because it does an amazing job to suit the needs of cartographers. 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.
Essentially pdfs can be deconvoluted into vector and raster components by a variety of easily accessed programs. The three basic symbol types for vector data are points, lines and polygons areas. Gis based measurements that combine native raster and native vector data are commonly used in environmental assessments. Lecture 1 intro to gis and gis vector and raster data models. Within the spatial referenced data group, the gis data can be further classified into two different types. Raster pdf files are traced since there is no data to extract. 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.
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. These features are the basic features in a vector based gis, such as arcgis 9. What is the difference between vector and raster data. What is the difference between vector and raster data models. Advanced gis spatial analysis using raster and vector data j8747 december 2001 2 who uses arcgis spatial analyst. Most useful ive found is pd2cad which make a dxf file from the vector. These data sources also has multiple file formats in them which are often used to express the geographical features.
Introduction to gis basics, data, analysis case studies. By and large, all the key cultural and physical vector gis datasets are at a global scale conveniently for you to use. This is an approximation and requires operator involvement as well as manual cleanup. Import into gis and convert to native points, lines, polygons. The unique feature of geographic information systems gis and other forms of historical data visualization is the. Both vector and raster data can model discrete and continuous data, but vector data be er for discrete data raster data be er for con nuous data decision also depends on the scale or resolution of data, analysis workflow, and tools available.
Raster data is made up of pixels or cells, and each pixel has an associated value. Most of these measurements can be calculated using either raster or vector data formats and processing methods. The raster data model is a widely used method of storing geographic data. In gis, vector and raster are two different ways of representing spatial data. Raster to vector conversion for overlay analysis in some cases, it may be necessary to perform vector based analyses on a raster data set, or vice versa. A data model in gis is a mathematical construct for representing geographic objects or surfaces as data.
Apr, 2016 a short and sweet description of the two data models and how they handle object versus discrete phenomena. Vector data is focused on modeling discrete features with precise shapes and boundaries. Vector data is exported to eps, pdf, and ai as raster in arcmap description. It is one of the two main types of gis data models, the other being the raster data model. Chapter 9 gis data collection 117 gis data collection. The vector model uses points and line segments to identify locations on the earth. The raster data model, along with the vector data model, is one of the. Chapter 8 spatial operations and vector overlays intro. Raster to vector conversion for overlay analysis trent university. Convert raster gis data to vector in arcmap youtube.