Intro to advanced GIS and a review of basic GIS Topic 1 Outlines About the class setting Materials to be covered and scheduled Quick review of GIS basics First lab Lab 1 Materials to be covered and scheduled A review of basic GIS 1 Spatial data analysis Vector data analysis 2 3 4 Raster data analysis 5 6 Spatial interpolation 7 8 3 D analysis 12 Geoprocessing 9 10 11 Other topics 13 We do not use one single book because there is no single book covering all the materials I will cover in the class 1 I will assign many ESRI ebook for you to read 2 Many papers for you to read 3 I will give quiz occasionally to see if you read them or not 4 Other policies refer to the syllabus What is GIS A computer system for collecting storing manipulating analyzing displaying and querying geographically related information In general GIS cover 3 components Computer system Hardware Computer plotter printer digitizer Software and appropriate procedures Spatially referenced or geographic data People to carry out various management and analysis tasks Geographic Data Geospatial data tells you where it is and attribute data tells you what it is Metadata describes both geospatial and attribute data In GIS we call geographic data as GIS data or spatial da 1 Geospatial data Traditional method To represent the geographic data is paper based maps Geology map Topographic map City street map we still use it a lot Characteristics of spatial data mappable characteristics Location coordinate system will be lectured later Size is calculated by the amount length area perimeter of the data Shape is defined as shape point line area of the feature Discrete or continuous Spatial relationships Discrete and continuous Discrete data are distinct features that have definite boundaries and identities A district houses towns agricultural fields rivers highways Continuous data has no define borders or distinctive values instead a transition from one value to another Temperature precipitation elevation GIS a simplified view of the real world Discrete features Points Lines Areas Networks A series of interconnecting lines Surfaces Continuous features Road network River network Sewage network Elevation surface Temperature surface features may still exist but let s live on it Dynamic nature not static Identification of discrete and continuous features Forest grow River channel change City expand or decline Road to be a line or a area Scale Some may not fit to any type of features fuzzy boundaries Transition area between woodland and grassland Lets do not worry about these problems now Just keep in mind Points A point is a 0 dimensional object and has only the property of location x y Points can be used to Model features such as a well building power pole sample location ect Other name for a point are vertex node Point Lines A line is a one dimensional object that has the property of length Lines can be used to represent road streams faults dikes maker beds boundary contacts etc Lines are also called an edge link chain arc In an ArcInfo coverage an arc starts with a node has zero or more vertices and ends with a node Line Areas Polygons A polygon is a two dimensional object with properties of area and perimeter A polygon can represent a city geologic formation dike lake river ect Other name for polygons face zone Area Topology needed A collection of numeric data which clearly describes adjacency containment coincidence and connectivity between map features and which can be stored and manipulated by a computer A set of rules on how objects relate to each other Major difference in file formats Higher level objects have special topology rules Topology Paul Bolstad GIS Fundamentals Two basic data models to represent these features Raster spatial data model Define space as an array of equally sized cells arranged in rows and columns Each cell contains an attribute value and location coordinates Individual cells as building blocks for creating images of point line area network and surface Continuous raster Discrete raster Numeric values range smoothly from one location to another for example DEM temperature remote sensing images etc Relative few possible values to repeat themselves in adjacent cells for example land use soil types etc Vector spatial data model Use x y coordinates to represent point line area network surface Point as a single coordinate pair line and polygon as ordered lists of vertices while attributes are associated with each features Usually are discrete features DIGITAL SPATIAL DATA RASTER VECTOR Real World Source Defense Mapping School National Imagery and Mapping Agency Raster and Vector Data Models Real World 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 G B G G B B BG G B G G B G BK B G B B B B Raster Representation 600 Trees 500 400 Y AXIS Trees 300 House 200 River 100 100 200 300 400 500 X AXIS 600 Vector Representation Source Defense Mapping School National Imagery and Mapping Agency Example Discrete raster Example continuous raster Xie et al 2005 Raster Real world Vector Heywood et al 2006 Effects of changing resolution Heywood et al 2006 Vector Advantages and Disadvantages Advantages Good representation of reality Compact data structure Topology can be described in a network Accurate graphics Disadvantages Complex data structures Simulation may be difficult Some spatial analysis is difficult or impossible to perform Raster Advantages and Disadvantages Advantages Simple data structure Easy overlay Various kinds of spatial analysis Uniform size and shape Cheaper technology Disadvantages Large amount of data Less pretty Projection transformation is difficult Different scales between layers can be a nightmare May lose information due to generalization GIS data formats file formats Vector data Shapefiles Coverages TIN e g elevation can be stored as TIN Raster data Triangulated Irregular Network Grid e g elevation can be stored as Grid Image e g elevation can be stored as image all remote sensing images Shape Files Nontopological Advantages no overhead to process topology Disadvantages polygons are double digitized no topologic data checking At least 3 files shp shx dbf Coverages Original ArcInfo Format Directory With Several Files Database Files are stored in the Info Directory Uses Arc Node Topology Containment coincident Connectivity Adjacency TIN A triangulated irregular network TIN is a data model that is used to represent three dimensional objects In this case x y and z values represent points Using methods of