Lecture 1 intro to gis and gis vector and raster data models. 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. We will examine two of the more common data structures here vector data model. Maidment, introduction to spatial hydrology esri campus continuous surfaces can be represented using the grid or raster data model in.
You will know the difference between raster and vector data in gis you will know when. Format description for vpf the vector product format vpf is a standard format, structure, and organization for large geographic databases based on a georelational data model intended. Raster data models have been updated mainly for data structure and data compression. Instead, vector graphics are comprised of vertices and paths. There are many analysis that make use of both data models i. Spatial data can represent vector and raster data models realworld features that have discrete boundaries such as roads, buildings, lakes, rivers, administrative boundaries as well as real. The objective of this section is to understand how raster data models are implemented in gis applications. Unlike vector data models, which show geographic data through. Raster data tend to require large amount of computer memory. Vector data model a representation of the world using points, lines, and polygons. All topological data models have not been implemented in gis probably.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. Raster data models present information through a grid of cells raster grids are usually made up of square or rectangular cells. Vector data models can be structured many different ways. In the vector based model figure 4, geospatial data is represented in the form of coordinates. Digital elevation models and different types of resolutions. Such a hybrid system can process raster data as well as vector data in an integrated manner taking uncertainty into account. Vector data models structures vector data models can be structured many different ways. Electronic maps emaps provide people with convenience in realworld space.
Image data utilizes techniques very similar to raster data, however typically. Tiled vector data model for the geographical features of symbolized. Different types of vector data and concept of topology nptel. When should we use raster and when should we use vector.
Raster data models and comparisons with vector youtube. Vector data also needs a lot of work and maintenance to ensure that it is accurate and reliable. Vector representation vector representation of data in the vector based model figure 4, geospatial data is represented in the form of coordinates. In vector data, the basic units of spatial information are points, lines and. The two primary types of spatial data are vector and raster data in gis. Vector data model individual vector gis files point, line, polygon are in a typical gis software represented by layers, which are stacked on top of each other, creating chosen geographical content. Introduction to gis and spatial data vector and raster comparison vector raster compact data structure for homogenous areas. Vector representation of data in the vector based model, geospatial data is represented in the form of coordinates. Layers representing two line and one polygon gis file. There are several advantages and disadvantages for using either the vector or raster data model to store spatial data.
Complex data structures means that phenomenonologically recognizable combination of several vector polygon maps through. Rasters are especially well suited for storing continuous data such as temperature and elevation values. Gis data model set of constructsrules for describing or representing the real world within a computer two data models vector raster 3. What is the difference between vector and raster data. Spatial data models vector data model points, lines, areas objectbased raster data model exhaustive regular or irregular partitioning of space locationbased the vector data model uses. Inaccurate vector data can occur when the instruments used to capture the data are not. We will examine two of the more common data structures here. Instead, vector graphics are comprised of vertices. The raster data model is widely used in applications ranging far beyond. In contrast to the raster data model is the vector data model. Vector models are useful for storing data that has discrete boundaries, such as country borders, land parcels, and streets. A data model is a way of defining and representing real world surfaces and characteristics in gis.
Raster twister model builder demo and data raster twister tools toolbox. In vector data, the basic units of spatial information are points, lines. But what is the difference between raster and vector data. 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. There are two primary types of spatial data models. Vector data models use discrete elements such as points, lines, and polygons to represent the geometry of real world entities figure 26. Raster vector comparisons raster vector spatial location implicit explicit attributes explicit for each cell implicit within data layer in either case the challenge is to. When would you use the vector data model versus the raster data model. Raster data models 262018 geo327g386g, ut austin 3 geo327g386g. The model most commonly takes the form of a gridlike structure that holds values at regularly spaced intervals over the extent of the raster. Cee 468668 gis applications in civil engineering university of nevada las vegas.
The raster data model jackson school of geosciences. In a vector data model, the computer stores points, lines and polygons as x and y locations a point feature would only have one x and y location associated with it. 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. Vector models are useful for storing data that has discrete boundaries, such as country borders, land parcels. The three basic symbol types for vector data are points, lines and polygons areas. Vector models are useful for storing data that has discrete boundaries, such as country. Data model overview a data model is a set of constructs for representing objects and processes in the digital environment of the computer decisions about the type of data. Vector and raster data models university of maryland. Vector field data model and operations xingong li department of geography, university of kansas, lawrence, kansas 66045 michael e. The raster data model is a widely used method of storing geographic data.
Can overlay displays easily can easily manipulate data. Difference between vector and raster data model vector data model. Using the same graph as before, a grid showing how vertexes can be joined by edges lines would be represented as. These are vital for translating our maps into digital formats. Spatial analysis using vectorbased data models taking advantage of gis to handle spatial operations spatial join issues. The vector data model is based on the assumption that. A data model in geographic information systems is a mathematical construct for representing geographic objects or surfaces as data. Currently used vector data models belong to any of the following types according to the complexity of the structure and the possibility of using topological. Shapes and locations of features on maps need to be described in numbers so the information can be read by computers. For this purpose a hybrid data model is defined and extended. Two common data models used to represent geographic data are the vector data model and the raster data model.
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