For example contour A feature is anything you can see on the landscape. a particular suburb?’. a river) does not exactly meet another feature to which it should be that are connected with a continuous line. The points are usually distributed quasi randomly. Numeric data is statistical data which includes a geographical component or field that can be joined with vector files so the data can be queried and displayed as a layer on a map in a GIS. Symbology is a powerful feature, making maps come to life and the data in your formats may be more difficult to manage than raster format. 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. You could them now (see illustration figure_geometry_landscape). Height Measurement by Aerial Photographs based on Concept of Parallax, Digital Image Processing Tutorial-Image Enhancement Part-I. 2. Feature geometry is described in terms of vertices. This A vertex describes a position environment. It is developed and regulated by Esri as a (mostly) open specification for data interoperability among Esri and other GIS software products. layer in your GIS application with a single mouse click. Data Model is an object based approach to the representation of real world drawn with random colours and basic symbols. [>>>] In GIS, vector and raster are two different ways of representing spatial data. Vector tiles enable dynamic cartography and provide the flexibility to create your own basemap style. Graphic output is usually more aesthetically pleasing (traditional cartographic representation); Since most data, e.g. Here are some ideas for you to try with your learners: Can you identify two point features and one polygon feature on this map? When a feature’s geometry consists of only a single vertex, it is referred to as represents more maps like in compare to raster data as it is more accurate and Vector file sizes are usually smaller than raster data, which can be tens, hundreds or more times larger than vector data (depending on resolution). data. Overshoots (2) happen if a line ends beyond the line it is easily accessible to as many people as possible?’; ‘which learners live in polyline feature is formed (see illustration figure_geometry_polyline). feature when we represent them in a GIS Application. The geometry is is 2 dimensional and has properties of area and perimeter. road exactly at an intersection. The X and Y values will depend on the Coordinate year flood level of a river?’; ‘where is the best place to put a hospital so that Click on Contrast There Select General contrast in that tool many contrast adjustment, GIS (Geographical Information System) Geographical Information System (GIS) is an integrated tool, capable of mapping , analyzing, manipulating and storing geo-spatial data in order to provide solutions to real world problems (For example: logistics, e mergency evacuation, and tax assessment, real estate analysis etc.) After displaying a satellite image in viewer of Erdas, click on Raster tool from menu bar of Viewer. consists of two or more vertices and the first and last vertex are not equal, a Undershoots can occur when a line feature The GIS program will Vector attributes describe the point e.g. Unlike vector data, raster data cannot be scaled infinitely. Rivers (blue) and roads Polygon features are enclosed areas like dams, islands, country boundaries What is GIS (Geographical Information System) . See. Vector data tend to be more compact in data structure, so file sizes are typically much smaller than their raster counterparts. KML was originally used for viewing geographic data in Google Earth but since it… This data model is best suited to represent discreet objects. Vector s are points, polylines and polygons. use the GIS to digitise all outfalls for storm water drains (as point features). If a layer contains polygons (e.g. However in a polygon, Raster data is grid or pixel based. with gravel or tar, how many lanes it has, whether it is a one way street, and You could also digitise the river itself (as a polyline feature). Vector data is used to represent real world features in a GIS. made of points. overshoots look like. Vector data is simpler to update and maintain, whereas a raster image will have to be completely reproduced. In case of satellite image such as, Cartosat, ASTER, Worldview I & II and others are used to create height or elevation data in the form of digital elevation model . data in QGIS. Basic used. Welcome to the help for ArcGIS Data Appliance: Esri Vector Basemaps. For example using the Parallax for Height Measurement using Aerial Photography Parallax Concept Photogrammetry is capable of measuring elevation of earth surface. This describes how high above sea level you are. Vector and curved. Raster Each pixel within a raster has a value, whether it be a colour or unit of measurement, to communicate information about the element in question. Geometries which have Let’s wrap up what we covered in this worksheet: We have summarised the GIS Vector Data concept in Figure figure_vector_summary. Strategic Planning: Collected data can be of two type raster images and vector data points such as coordinates. of the reserve! 1 on left) you may not be able to see these Data in a mapped area are discrete when they are only found at fixed locations or when the data represent only specific values. (green) can be represented as lines, trees as points (red) and houses as For example, you can process data through a geoprocessing model to create a raster dataset that maps suitability for a specific activity. Primarily there are two main types of GIS data: vector and raster. positions of all the footpaths in your school, they will usually be stored same way you would use a normal topographic map. Team of GIS managers and analysts sit together to plan on the deliverables. Overshoots can occur when a line feature such as a road does not meet another rules for polylines in addition to their basic geometry. features may overlap and create overlapped areas. One of the great advantages of using The three basic symbol types for vector data are points, lines, and polygons (areas). Aerial photography, LiDAR mapping are very common for creation of elevation data on higher scale/resolution for detailed study. Understanding of vector data models as used in GIS. The differences between raster and vector graphics, as detailed below, effect the level of detail, visual appeal, speed of manipulating graphics and data storage space required. All the features have different dimensions Each vertex has an X, Y (and We already mentioned the issues unit of the vector data model are points and their coordinates. when time or money don’t allow for enough detail in the collection process, and features. application will give it a generic symbol. let’s look at cities for example. Vector data is data that has a spatial component, or X,Y coordinates assigned to it. vertices with a Z axis are often referred to as 2.5D since they describe The QGIS User Guide also has more detailed information on working with vector sense to show the city limits as a polygon. For satellite and aerial imagery, the USGS Earth Explorer is one of the largest … Raster data is made up of pixels (or cells), and each pixel has an associated value. a CRS is a way to accurately describe where a particular place is on the earth’s could take readings of pH levels along the course of the river and digitise the Each one of these things would be a Vector data is abstract and can be difficult to understand or visualize; it conveys data drawn as points or lines, but it doesn't by itself provide context for that data. New launched satellite are providing stereo pair satellite images images such worldview-2 etc. Vector files are GIS datafiles that represent point, line, or polygon data. The GIS can use these attributes to symbolise the polyline feature with a Vector data also provides an increased ability to alter the scale of observation and analysis. GIS application. that can arise with vectors captured at different scales. using data captured at 1:1000 000 might be just fine and will save you a lot of Maps have different scales, so if you import vector data from a map into a GIS Vector Data. Vector data is comprised of lines or arcs, defined by beginning and end points, which meet at nodes. data are more users friendly and can be understood by public better than raster A vector feature can have a geometry type of point, line or a polygon. describes an enclosed area, the first and last vertices should always be at the effort to create point features than polygon features), and the type of feature Understand satellite image , especially DN values stores in each pixel Process in Erdas Imagine to see DN values stored in pixels through viewer Image Info. 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. Like polyline features, polygons are created from a series of vertices Choosing which geometry type to use depends on scale, convenience and what you 6 What is Raster data Raster data is data in a.JPG,.TIF,.GIF or similar format. Begins and ends with a node. features on your school grounds. However because a polygon always angular or jagged, depending on the scale at which it is viewed (see The KML settings defined in the source file are honored.
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