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									Geog5040: Using and adapting ArcGIS

                        Lecture two
                  A first look at ArcGIS
Format of lectures/workshops and
practicals in Weeks 2-6
In this GIS Lab for the lecture/workshop
  Mixture of lecture and hands-on
Also in this Lab for practical
  Hands-on with demonstrator support
  Assignment is linked to the practical
  5 practicals/5 assignments, each worth 5% of the
   module mark.
 Other practicals/assignments
  With Andy Evans for weeks 7-11 - 5 practicals/5
   assignments, each worth 5% of the module mark
  Computer project - 50% of module mark
Overview of Weeks 2-6 of GEOG5040
                         Weeks 7-11:
                                              Week 2:
                      Adapting ArcGIS
         Week 6:    (with Dr Andy Evans)   A first look at
        Rasters &                          ArcGIS and
        Surfaces                               ArcInfo
                                            Workstation

                       USING
                       ARCGIS

  Week 5:                                        Week 3:
  Spatial                                      Data – in, out
Manipulation                                  and shake it all
     &                                            about!
  Analysis              Week 4:
                    Tables, Querying,
                     Displaying and
                      Presentation
Week 2: A first look at ArcGIS

      Working with
       Coverages                       What IS ArcGIS?
    and command line

                        A first look
                        at ArcGIS

       How is data                     Where do I find
    stored in ArcGIS?                      help?


                        Who uses
                        ArcGIS?
Aims and objectives of this lecture
 This lecture aims to :
    Explain the different licences, components and applications that
     make up ArcGIS
    Provide information on where to find help in using ArcGIS
    Discuss some of the users of ArcGIS
    Describe raster and vector data models and the different data
     structures used in ArcGIS
    Introduce legacy ArcGIS
 Upon completion of this lecture/practical you should:
    Appreciate the various components and licenses that make up the
     ArcGIS suite
    Know where to obtain help when required
    Have a broad understanding of the way that data is stored in
     ArcGIS
    Have acquired knowledge and experience in using command line
     ArcGIS
What is ArcGIS?

      Working with
     Coverages and                     What IS ArcGIS?
     command line

                        A first look
                        at ArcGIS

       How is data                     Where do I find
    stored in ArcGIS?                      help?


                        Who uses
                        ArcGIS?
ArcGIS Licences

All look and work the same – differ on
 what they can do
                                  •ArcInfo has
                                  more tools than
                                  ArcView or
             Arcview              ArcEditor
                                  •Includes
                 ArcEditor
                                  ArcWorkstation
                                  (GIS standard
                        ArcInfo
                                  and still widely
                                  used)
ArcGIS Components and applications
                                             Arc
                                             Arcedit

                      ArcInfo Workstation    Arcplot
                                             ArcTools


                                             ArcCatalog
                      ArcGIS                 ArcMap
ArcGIS Desktop        Desktop Applications
    ArcInfo licence
                                             ArcToolbox

                                             ArcGlobe

                      MapManager             ArcScene
                      (Data converter)
                                             Version 6.2
                                             Version 9
Where do I find help?
                                         What IS ArcGIS?

      Working with
     Coverages and
     command line
                                            Where do I find
                          A first look          help?
                          at ArcGIS
                                         •Books
       How is data
    stored in ArcGIS?                    •ArcGIS Desktop help
                                         •ArcInfo Workstation
                        Who uses         ArcDoc
                        ArcGIS?          •Staff
                                         •Each other
             There’s not yet been any
Textbooks     textbook that covers ArcGIS
              fully, however “Inside ArcInfo”
              may be the best bet.
A newer textbook you may find useful

                       Amazon - £25.89
                       Published 2006
                       Mixture of GIS
                        concepts and a ‘how-
                        to’ manual.
                       Includes exercises
                        and a CD
Recommended book for ‘Using
ArcGIS’
                   •2nd edition(or 3rd edition if
                   you can get hold of it) is
                   updated to ArcGIS v9.0
                   •Very comprehensive
                   •Focuses on ArcView
                   licence functionality
                   •Available from Amazon or
                   McGraw Hill (publisher) -
                   http://www.mcgraw-
                   hill.co.uk/
                   •3 copies ordered by
                   Edward Boyle Library
Activity 1

Check the licence on your PC via the
 Desktop Administrator
  You cannot change the licence as it is
   controlled by the University/School IT staff


Explore ArcGIS Desktop help (both the
 version that is embedded in ArcGIS and
 the online version)
Who uses ArcGIS?

      Working with
    Coverages and                      What IS ArcGIS?
     command line

                        A first look
                        at ArcGIS

       How is data                     Where do I find
    stored in ArcGIS?                      help?


                        Who uses
                        ArcGIS?
Activity 2 - Discussion

In groups discuss:
  Who has used ArcGIS or any other GIS?
  What sort of things did you use it for?
  What other groups/organisations do you think
   may use it and why?
Each group report back briefly
 How is data stored in ArcGIS?

            Working with
           Coverages and                   What IS ArcGIS?
            command line

                           A first look
    How is data            at ArcGIS
 stored in ArcGIS?
                                           Where do I find
                                               help?

•Vector – focus of Weeks
2-5
                                Who uses
                                ArcGIS?
•Raster – covered in
more detail in Week 6
The General Data Model

 We break data up into its constituent parts or
  Features.
 We can do this splitting with most human-
  influenced data (eg. Towns, forests, boundaries
  etc.).
 Commonly ArcGIS deals with line and point data:
  Vector data.
  Basic Vector Types
 Label points (single x,y coordinate locations)…
  eg. phonebox on an Ordinance Survey (OS) map;
  eg. a town on a global map.
 Arcs (lines of multiple x,y coordinates)…
  eg. roads, rivers.
 Polygons (enclosed areas made from Arcs)…
  eg. house plans, parks, boundaries.
 Attributes (associated non-location information)…
  eg. census data for and area, house names, population
   numbers.
Raster data model
 Some data doesn’t easily break up into lines and
  points…
    eg. satellite images, terrain surfaces, photos.

 This is often handled as Raster data. At its simplest, a
  raster file contains one value for each pixel in an image.
 Obviously not very efficient to store compared with end
  points for a vector arc.

                                                20     20   20   20   90
                                                20     20   20   90   20
  0,10 100,90
                                                20     20   20   90   20
                                                20     20   90   20   20
                                                20     90   20   20   20
 Other data models
 Some terrain and other surfaces can be
  represented by lines.
 Done using a Triangulated Irregular Network or
  “TIN”.




 You can also use “Lattices” - regular grids of
  points, each with a height that makes an overall
  surface.
 We’ll look at non-Vector data in the coming
  weeks.
ArcGIS Vector data formats:

ArcGIS
  Shapefiles (layer-based GIS)
    ArcView files traditionally. Useful for moving data
     about.
  Personal geodatabases (object-orientated GIS)
  Server geodatabases (object-orientated GIS)
  Coverages (limited functionality in ArcGIS v9)
ArcInfo Workstation
  Coverages (layer-based GIS)
ArcGIS Vector data formats -
Topology
 One of the differences between the different
  data models is whether or not they are
  topological.
 Analysis we might want to do…
  “How do I move from Arc to Arc to get from A to B
   fastest?”
  “If I leave Polygon A going north, which Polygon do I
   enter?”
 To do these analyses we need some notion of
  Topology, ie. the spatial relationships between
  features.
Shapefiles
 A simple data structure developed for early
  version of ArcView
 Geographic component (.shp and .shx)
 Don’t store topological geometry or attribute
  information
 A feature is stored a a shape comprising of
  vector coordinates
 Attribute database stored separately as dBase
  file (extension .dbf)
 Fast processing speed and drawing speed
 Usually economical on storage space
 Easy to transfer data between users
How data is stored in a shapefile
 Points, polylines or polygons can be represented
 Points – every point is a single record in
  database
 Polygons – every polygon is a stand-alone entity
  No topology
  Slivers can be a problem
  Adjacent boundaries are double digitised
  Some of the spatial processing tools in ArcTools do
   not work on shapefiles
Geodatabases

Personal and ArcSDE (enterprise)
Powerful and sophisticated
Works on premise that ‘objects’ depict
 real-world entities, in both description and
 behaviour
Geograpy and attribute stored in a DBMS
 (e.g. Oracle or Microsoft SQL Server for
 ArcSDE/ Microsoft Access for personal
 geodatabase)
Data storage in a geodatabase

An ‘object’ (i.e. a point, a line feature or a
 polygon feature) is stored in a single row
 in an attribute database.
Data integrity by use of domains
  Faster data entry
  Prevents mis-entry
  Allows default values
We will be looking at and creating
 geodatabases next week
Coverages
 First data model created by ESRI
 Linear features and polygons are made up of
  “arcs” – to give the Arc in ArcINFO
 Attribute data is stored in a relational database
  INFO
 Less sophisticated than geodatabases but
  contain topology
 More complex to understand than shapefiles or
  geodatabases
 Still a number of coverages around
 Cover in more detail in the next section
 Activity 3 – Check properties of
 Wyorks shapefiles
 Open ArcCatalog
 Navigate to the WYorks shapefile that you looked at in Week
  1 practical
 Right-click on the shapefile and choose Properties from the
  context menu
 Look at/explore each of the 4 tabs in turn (General, XY
  Coordinate system, Fields and Index)
    What type of features does this file store?
    What coordinate system is set? Can you work out how to select the
     predefined, projected coordinate system, British National Grid?
 Checking properties can be done for any dataset –
  shapefiles, geodatabases or coverages.
 Activity 4 – Explore ArcMap
 Download activitydata zip file from Blackboard and unzip.
 Open ArcCatalog and locate the files
 Open ArcMap and add the lakes, rivers and world data to
  the map view in that order.
 What is the assumed projection or coordinate system that
  ArcGIS has adopted?
 Use zoom, change symbol settings, experiment with layer
  ordering.
 Activity 5 – Personal Geodatabase
 and saving
 Return to ArcCatalog and create a personal geodatabase
  (File>New>Personal Geodatabase). Call it World.mdb.
 Right-click on the World.mdb and select Import>Feature
  Class (single) to import the shapefiles directly into the
  World.mdb file.
 Once completed you have created a personal geodatabase
  and populated it with shapefiles. Look at how the
  geodatabase and feature classes are represented in the
  Table of Contents.
 Use the Save As option in the File dropdown menu to craete
  a new *.mxd ArcMap document – this allows you to return to
  the same set of open tables, layer properties etc next time.
Working with Coverages and
command line

      Working with
       Coverages                       What IS ArcGIS?
    and command line

                        A first look
                        at ArcGIS

       How is data                     Where do I find
    stored in ArcGIS?                      help?


                        Who uses
                        ArcGIS?
Why are we talking about coverages
and command line?
ArcGIS can use both old and new data
 models
BUT
Some important functions are only
 available for the old coverages
Other functions only operate on the new
 type of files
Therefore you need to understand (and be
 able to work with) both old and new
Command line

What do we mean by command line?
  User types command into a window to make the
   program work
  No Graphical User Interface (GUI)
  Not as intuitive
The ArcInfo Data Model - Coverages
 Store all the same types of features in one file
  using x,y coordinates…
   i.e. all the point features in one file, all the line
    features in another file, and all the associated non-
    location data in yet another file.

 Makes storage and handling easier.
 Makes analysis easier.
 The filenames show what kind of data they
  hold.
   e.g. Label Points are stored in a LAB (lab.adf) file.
Tics
 Tics – geographical control points used to register
  (overlap) different datasets, and transform (eg. put in a
  new projection scheme) the data.
 For example, you might mark in known locations on two
  datasets, usually at the data edges, as Tics.




 Stored in a TIC file (tic.adf).
Arcs
 Arcs - stored in an ARC file (arc.adf).
 A point where an Arc changes direction is
  called a “Vertex”.
 The start and ends of Arcs, and the crossing
  point between two Arcs, are called “Nodes”.
 The ARC file stores each Vertex and Node as
  an x,y coordinate.

                                  Data can be assigned
                                  to Nodes
Polygons
 An area - can also have “islands” inside, that
  cut out inner areas.
                                +42




 Made from one (or more) Arcs.
 The end Node is the same as the starting
  one.
 Each also has a Label Point (x,y) associated
  with it, stored in a LAB file.
 Storing Vector data

 The files hold coordinate data and Feature
  Numbers that are assigned sequentially to
  Features in the file.
          Feature Number   Coordinates

          #1               0,0 10,10

          #2               10,10 10,0

          #3               0,0 10,0
Polygon-Arc List
 The Polygon-Arc List file (pal.adf) stores which
  Arcs make up each Polygon. That way we don’t
  need to store the Arc coordinates again.
                                                 ARC
PAL                              Feature   X,Y
Feature   Arcs                   Number
Number                           #1        0,0 10,10
23        #1,#2,#3
                                 #2        10,10 10,0

                                 #3        0,0 10,0



                     #1
                           #2
                       +23
                      #3
Polygon-Arc List
 The outside or “Universe” Polygon is always
  feature number 1, ie. first in the PAL file.

 Islands start with a zero, followed by the Arcs.
Feature Attributes
 Info stores information about each feature in a Feature
  Attribute Table using the Feature Number to match the
  attribute data to the coordinates in the other files in a
  one-to-one relationship. Each data type has its own table
  type.
 Each feature will also have a unique User Defined ID
  kept in its table in addition to its Feature Number.

PAL                       FAT
Arc             Polygon    Polygon   User      Type     Use
Feature         Feature    Feature   Defined
Numbers         Number     Number    ID
#1,#2,#3        23         23        44        Park     Public
#111,#154,#16   24         24        56        Garden   Domestic

#22,#34,#17     42         42        47        Pond     Public
 Types of Feature Attribute Table
 Label Points / Polygons – Point/Polygon Attribute
  Table (PAT / pat.adf file).
   Includes AREA and PERIMETER columns with the values
    associated with any Polygons for which the Points are
    labels.
   Can be used to hold points or Polygon labels, but not both.

 Arcs – Arc Attribute Table (AAT / aat.adf file).
   Includes FNODE#, TNODE#, LPOLY#, RPOLY#,
    LENGTH columns.

 When Nodes have data associated with them -
  Node Attribute Table (NAT / nat.adf file).
   Includes an ARC# column referencing one of the Arcs.
Feature Attribute Table Format

  After the columns listed above usually come
   the Feature Number (NAME#) and the User
   Defined ID (NAME-ID) columns.

  Following these, users can then create more
   columns to hold attribute data.
Example PAT
 Note that the Universe Polygon is first, and
  the AREA given for it is the negative total of
  the rest.
AREA           PERIMETER   SOILS#   SOILS-ID   SOIL-CODE


-2021474.264   8606.065    1        0

1186954.500    6134.177    2        43         Water

369.352        92.042      3        1          Id3

393753.469     7345.473    4        2          Sg

10962.990      492.525     5        3          Id3

14700.509      468.122     6        4          Id3

18515.934      589.712     7        5          Ns1
Other Vector data
 Region – several related Polygons, nested or
  overlapping. Stored in a PAT.regionName (pat.adf file).

 Annotation – text drawn along an associated feature.
  Stored in a T(ext)AT (txt.adf file).

 Section – an Arc / portion of Arc representing a part of a
  pathway. Stored in a SEC table (sec.adf file).

 Route – a pathway made out of multiple Sections.
  Stored in a R(oute)AT (rat.adf file).
Topology in coverages
 Three ways topology is defined in ArcInfo…

  Arcs connect at Nodes.
  Arcs have direction, and therefore a left and right
   side.
  Arcs that connect to surround an area make a
   Polygon.
How Topology is stored
                                     Note that polygons are listed
Stored in the files.                clockwise in the PAL, with minus
                                     figures for reverse direction Arcs.
                       N2                 PAL
                                          Feature   Arcs
           +23                            Number
     N1               N3                  1         Outside Arcs

                                          23        #1,#2,-#3

ARC/ATT
Feature   X,Y          From   To     Left            Right
Number                 Node   Node   Polygon         Polygon
#1        0,0 10,10    N1     N2     1               23

#2        10,10 10,0   N2     N3     1               23

#3        10,0 0,0     N1     N3     23              1
Activity 5 – Topology in Coverages

Fill in tables listing arcs making up
 Polygon-Arc List and define topology of
 polygons.
  Putting features together
 So, we’ve seen that individual
  features are stored in files with similar
  types (e.g. all the line features in a file
  of Arcs).
 When these are combined, you get a
  data “Coverage”. A Coverage usually
  contains one type of geographical
  information or analysis result, e.g.
  “Geology”, “Roads”, or “Quickest
  routes”
 Several Coverages may go together
  in a map, and you can turn different
  ones on and off to display different
  facets of a map.
Coverages

 In the file system, these are represented as
  the directories your data files go in.
 They let you keep data files together and
  display them at the same time.
 Usually it is the name of the Coverage that
  goes to form the Feature Number and ID
  column names.
  E.g. The SOILS coverage before gave our example
   PAT a SOILS# Feature Number column and a
   SOILS-ID column.
Additional Coverage information
 As well as our data files, a Coverage will have
  several other pieces of information associated
  with it.
  A Coverage Extent (BND / bnd.adf file) - this records the
   upper right and lower left corners of a rectangle containing
   all the feature data in the Coverage. It need not contain all
   the Tic and Annotation points.
  A Coordinate Definition file (PRJ / prj.adf ) - holds the
   Coverage’s map projection information
  A Tolerances file (TOL / tol.adf ) - holds a number of
   processing tolerances, eg. How close Tics in different files
   need to be before they count as matching.
  Putting Coverages together
 Finally Coverages can be kept together in project areas
  called “Workspaces”.

 Workspaces allow you to keep all the data and Coverages
  you generate for a project in one place, separate from any
  other work you may be doing.

 In the file system they’re represented as directories which
  include all the Coverage directories you’re working on in a
  project.

 One of the first things you do on starting any
  ArcWorkstation project is move to your Workspace using
  the w command.
   w m:\workspace\schools
The Vector Data Model
Different views of the same data.
 ArcCatalog                  File system



              Workspace
              Coverages
              Vector data


              Raster data
               TIN data
Practical – using ArcEdit

This section will provide background
 information for next Monday’s practical
Focuses on the editing of data using
 command line instructions in
 ArcWorkstation
  What’s ArcWorkstation made up of?
 Made up of separate modules that communicate with each other. The
  command line interface is…

              Arc: core application for doing analysis, and using
       “workspaces” where all the files are kept for each
              project.
              ArcEdit: for editing maps interactively.
              ArcPlot: for neat plotting of maps.
              ArcTools: Pre-made AML scripts
              Grid: for working with image files/raster
              data.
              ArcDoc: Help pages

                  (Might also see on older systems: ArcTIN: 3D work; ArcPress:
      printing; ArcStorm: multiuser databases; ArcNetwork: networks).
Making a Workspace
 Making a new Workspace is as easy as making
  a new folder.

 File > New > ArcInfo Workspace
  (or right-click > New > ArcInfo Workspace)


 Rename the Workspace appropriately.
 Note: This fails if you have a space in the path
 If you look in Explorer, you’ll see an Info
  directory has been made in the Workspace
  directory to store related information.
  Importing Coverages
 Usual to import a “Interchange file” (.e00) –
  using ArcToolbox.
 These contain geography and attribute data.
 Usual to transfer your Coverages to others in
  this form.
Making a Coverage

 You won’t need to do this in the practical
  as you will be given a Coverage but if you
  ever needed to make a Coverage then
  these next 4 slides explain how to do this.
 Making a Coverage is almost as easy, but
  requires slightly more thought.
 File > New > Coverage…
 This brings up a “Wizard” (set of instructional
  forms to fill in) to help you.
Name the Coverage
 You can use an existing coverage to supply
  boundary, tic and projection information.
Fix the projection
 If you don’t supply a template, you’ll need to
  say what projection scheme it’s in, or pick
  none.
Generate initial topology
 If you know which feature type will be
  important, you can generate the appropriate
  feature table.
Using ArcEdit to edit a Coverage
Coverages cannot be edited in ArcMap so must be
  done in ArcEdit
 Command line driven
 Display map using mapextent, edit and
  drawenvironment (de) commands
 Use editfeature (ef) to correct
  undershoots and overshoots
 Extent tool allows you to zoom in for more
  accurate editing
 Delete and add new features
 Use quit to exit ArcEdit
 Building Topology
 Once you have your data in, you’ll need to build the
  Topology information in order to do analyses.

 Before you can build your Topology you’ll need to clean it.

 Cleaning involves making sure each line has the
  appropriate Nodes (e.g. where they cross) and Polygons
  don’t overlap.

 Adds Nodes and splits Polygons.

 You can do this with the build and clean commands in
  ArcEdit (see the ArcDocs), but it’s much easier in
  ArcCatalog.
When to Clean and Build

 Imported Coverages need cleaning and
  building.
 As does data developed in ArcWorkstation.
 Not necessary in Geodatabases.
Fuzzy Tolerance
 Fuzzy Tolerance : the distance up to which points will be
  considered the same and snapped to the same point.
 This helps eliminate slithers.
 Should be small (~1/100,000 BDN rectangle size). If too
  small an automatic value is given (see ArcDocs).


                   X 200                  X 200
x1




                   uncleaned             cleaned
Dangles
 Dangle Length : any overshooting Arc longer than this
  won’t be removed as an error.
 Usually zero for Arc Coverages, 0.05 inches (0.127 cm)
  for Polygons.
 Note that Tolerances can be set in the Coverage
  properties before this time (sets the TOL Table / file).


                   X 200                  X 200
x1




                   uncleaned             cleaned
Summary
      Working with
       Coverages                            What IS ArcGIS?
    and command line
                                               •ArcWorkstation
   •More detail on
                                               •ArcGIS
   coverages
                                                   •ArcCatalog
   •Brief look at how to
                                                   •ArcMap
   use ArcEdit              A first look
                                                   •ArcToolbox
                            at ArcGIS

      How is data                                Where do I find
   stored in ArcGIS?                                 help?

   Concentrated on                               •Books
   Vector data               Who uses            •ArcGIS Desktop help
   model:                    ArcGIS?             •ArcInfo Workstation
   •Shapefiles                                   ArcDoc
   •Geodatabases           Discussion on         •Staff
   •Coverages              experience and        •Each other
                           possible users
Practical

Import a coverage into ArcGIS
Use ArcEdit to edit, display, clean and
 build a coverage
Assessed work: Output from practical
 session
Practical

This practical will give you experience in:
  Using ArcWorkstation
  Using Command Line
  Working with coverages
  Editing coverages – deleting and adding arcs
  Building arcs into polygons
Next week

Geographical Data – in, out and shake it
 all about!
  Using ArcGIS to add data, edit and manipulate
   data and export data

								
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