Major parts of Arc

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Major parts of Arc

• ArcView -Basic mapping, editing and Analysis
  tools
• ArcEditor -all of ArcView plus Adds ability to
  deal with topological and network
  editing-additional stuff in Arctoolbox
• ArcInfo- fully functional everything

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Definitions

• Features
• points, lines, or polygons with x,y coordinates
  marking the location of points, nodes or vertices
• Node- the end points of a line
• Vertices - the corners of a polygon
• Feature Classes
• Contains a number of different features that are
  all the same type of geometry
• e.g., they can multiple feature files that are
  all point features, but not some combo of points,
  lines and polygons

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Data Types

• Raster vs Vector
• Raster is turning pixels on and off and giving
  them values
• Advantages- looks like a photograph
• Disadvantages- at high magnification things can
  look jagged as pixels are square
• Vector- uses x,y coordinates to create points,
  lines and shapes
• Advantage is things are smooth at high
  magnification
• Disadvantage is that it looks like a line drawing

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Data files in ArcGIS

• Shapefiles
• Vector data files
• Can be points, lines or polygons
• Cannot store topological data
• Files have the suffixes .shp, .dbf or .shx
• Icons are green with different symbols for points
  lines and polygons

Icons for the three types of vector features
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Data files in ArcGIS

• Coverages- topological data sets that contain
  multiple features classes
• Files are commonly spread among multiple folders
• Coverages have a folder with files that have the
  suffix .adf and a file called info that must be
  in the same location as the .adf file

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Data files in ArcGIS

• Geodatabases- one of the newer types of files
• Contains multiple types of of features classes
• Can also contain tabular files that are not
  linked to spatial locations
• They can store topological relationships between
  different data sets

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Data files in ArcGIS

• Layer files-A layer file contains references to
  spatial data and how it should be displayed and
  what basic properties it has
• Example, a layer file with basic map symbols can
  be placed into any work so that there is
  consistency between jobs (maps) of various types

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Data files in ArcGIS

• RASTERS- rasters are arrays of numbers stored in
  binary format. RASTER files have the data
  itself, plus some critical information about how
  the array is set up and how it is georeferenced
• These can be displayed in a variety of ways, but
  can only be analyzed when they are converted to
  grid files

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Data files in ArcGIS

• Tables- these can exist as separate files or
  associated with other files.
• They can have the suffix .dbf (database file) or
  as comma delimited text files
• INFO files are commonly stored as standalone
  tables with a yellow stripe at the top of the
  table

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Data files in ArcGIS

• Grids - a specilized data file developed by the
  software manufacturer to allow for rapid
  manipulation or analysis of RASTER data

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Data files in ArcGIS

• TINs- Triangulated Irregular Networks store
  surface information such as elevation
• Uses nodes (points) to define triangular shaped
  planar surfaces.
• Tins are used to create contour maps and analyze
  3D surface information

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Metadata

• Data about the data
• Includes
• who created the file
• What coordinate system it uses
• What the fields in the attribute tables mean
• What are the abbreviations
• Plus other information
• It is time consuming to create, but ArcGIS will
  assist in the adding information to the file and
  in making sure that the metadata stays with the
  appropriate files

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ArcCatalog

• Like have windows explorer operating within the
  GIS software
• It knows how to organize and manipulate and store
  information within itself

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Topological models

• How features (polygons, points, lines) relate to
  each other
• Adjacency- sharing of a boundary
• State lines, county lines
• Connectivity- how things connect
• if one stream flows into another stream
• Overlap- if data relates to same are more than
  once
• Spraying of pesticides over the same area
• Intersection- types of interactions
• Highway goes over or has onramps to a crossing
  road

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Precision vs Accuracy
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Accuracy

• Geometric Accuracy
• How closely do the x,y coordinates of features or
  raster data reflect their position on the earth?
• Thematic Accuracy
• Refers to the accuracy of attributes
• Is the population of the city really 734, or is
  it 7340?

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Image service vs Feature service data servers

• Image services
• Can view and print out images, but cannot
  download or manipulate the files
• Feature services
• Can download, view, and printout data

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• http//www.geographynetwork.com

Try to find one of each on this site.