Data Management and Display

1
Lecture 4

• Data Management and Display

2
This Lecture

• Review of Tables in ArcWorkstation.
• Tables in ArcMap.
• Table Relates.
• Mapping.

3
Coverage Feature Attribute Tables

• 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 geography files in a one-to-one
  relationship. Each data type has its own table
  type.

PAL
FAT
4
Types of Feature Attribute Table

• Label Points 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.
• Arcs Arc Attribute Table (ATT / att.adf file).
• Includes FNODE, TNODE, LPOLY, RPOLY, LENGTH
  columns.

5
Example PAT

• Note that this Table has an extra, non-standard
  column in it SOIL-CODE.

6
Joins

• You can produce data tables that float free from
  the FATs.
• If these have one column data in them that is
• Unique i.e. is different for each record.
• Also present in a FAT.
• you can JOIN the Tables, that is, copy all or
  some of the data out of the free-floating table
  and into the FAT.

New FAT
Data
FAT
7
Practical ArcWorkstation and INFO.

• Joins.
• Altering records.
• Adding new data without Joins.
• Making Tables from scratch.

8
Tables in ArcMap

• Selection
• Editing

9
Tables in ArcMap

• You can use ArcMap to adjust Tables and select
  data/map areas from each other.

10
Table Selections

• Brushing selecting map areas using the
  selection tool highlights the Table records, and
  vice versa (use Shift to select several)
• Select by Location / Attributes.
• Sorting whole Table by column click column to
  select, then right-click selected column top to
  pick sorting (ascending / descending).
• To sort by more than one column - drag column
  top so first column to the left of second.
  Highlight both and click one top to select
  sorting.

11
Data Mining

• Selection brushing is a central part of many Data
  Mining applications.
• For example where are the top ten earthquake
  zones?
• Import global map of earthquake frequencies.
• Open attribute Table and sort on frequency
  column.
• Select the top ten Records.
• Save the selected areas.

12
Attributes Editing

• Once Attribute Fields are created you can alter
  them from the defaults.
• While in Edit mode, select Features.
• Choose start editing
• Hit the View Attributes icon (you may have to add
  this using View gt Toolbars gt Customise).

13
Attribute Editing

• You can then alter attributes by clicking over
  their figures and changing them. Things you
  shouldnt change wont let you change them.

Arc Feature
Geodatabase Feature
14
Table Editing

• Some tables you can edit directly in ArcMap.
• You can use the Add Data button to add
  non-geographical tables to the Contents Tree.
• You can
• Add Records to bottom of Tables.
• Click and copy, paste, and edit Data Item values.
• There are also ArcToolbox tools under Tables for
  dealing with making and editing Tables.

15
Table Calculations

• ArcMap Calculating editable column values in
  Tables
• select one, many (using Ctrl), or all of the
  Records/rows
• right-click the appropriate column top and select
  Calculate Values
• Form an expression or click Advanced and type in
  a VBScript expression.
• VBScript tutorial at
• http//www.intranetjournal.com/corner/wrox/progref
  /vbt/
• You can save or load your expressions as .cal
  files.

16
Table Calculations in ArcWorkstation

• In INFO use the CALC command.
• Select Table / Records to act on.
• Issue CALC command.
• Results can only be numeric.
• Can use other columns, e.g
• CALCULATE ANNUAL_WAGE MONTHLY 12
• For non-numeric you need an AML or Java routine.

17
Table Relates

• INFO is a relational database one Table item can
  be linked to multiple items in other Tables.
• Types of Relate
• Relates in Coverages
• Relation Objects in Geodatabases

18
Table Joins

• The relationship between items in a join must be
  one-to-one.
• If not, JOIN will take the first value it comes
  across.

FAT
External Table
Resulting Join Table
19
Table Relates

• This is done without adding the data to the
  Table, therefore storage space lower than a Join.
  Also means a group of people can access one large
  geography file, but connect different data to it.
• Usual to link a Feature Attribute Table (FAT) to
  an external data table.
• E.g. link a country geography to Tables of
  population, domestic products, etc.

20
Table Relates

• Relates can store one-to-many relationships and
  they can be used in analysis.
• E.g. Show all SITES where at least one month has
  gt 300mm RAINFALL and show the MONTH.
• Again, there must be an identically named column
  in each, holding the data used to link the Tables.

FAT
External Table
Result
21
ArcWorkstation vs. ArcGIS

• Note ArcWorkstation can do many-to-one, but not
  one-to-many. ArcDesktop can do both.

Many-to-one
One-to-many
22
Coverage Relate Arc commands

• relate add
• Interactively or in one go, add a relate. You can
  have up to 100 at a time before you have to
  redefine one.
• relate drop
• Remove a relate.
• relate save name
• Saves a current set of relates to a file.
• relate restore name
• Gets saved relates.
• relate list
• Lists current relates.

23
Interfaces

• Can be done in ArcToolbox using the Relate
  Manager. This will apply to any Workspace.
• In a particular Workspace can be done in ArcTools
  using Manage gt Relates or in Arc using the Relate
  command.

24
Interfaces

• ArcToolbox, ArcTools, Arc

25
Parts of a relate

• Relation name arbitrary name lt 8 letters.
• Table Identifier name of the Table usually not
  a Feature Attribute Table (FAT).
• Database usually INFO. Note that you dont
  specify a table the relate works on any table
  with the right column usually a FAT.
• Info Item the column in the INFO FATs.
• Relate column column in the non-FAT table
• Relate Type how the Tables are linked.
• Relate access rw (read-write), ro (read only) or
  auto (same as the FAT).

26
Types of relate

• This is determined by the sorting in the Tables.
• Linear no sorting slow unless the FAT and
  external table are sorted, in which case fast.
• Ordered related non-FAT table must be sorted by
  the values in the Relate column.
• Link relate by Feature ID. Shouldnt be used,
  as the system can change IDs without warning,
  making the relate outdated.
• Table same conditions as ordered but if an
  absolute match is missing the record in the
  related table with the next highest value is
  taken.
• First only option if you are not working with
  INFO.

27
Using Relates

• Once set up, can be used anywhere youd use a
  Item value.
• relateName//itemName
• Where itemName is the Item in the related Table.
• Cant use them inside INFO, just the other
  modules a typical use would be to plot
  something like language on a world map, where
  theres a one language many countries relation.

28
GeodatabaseRelationships

• Encapsulated in Relationship Class Objects.
• Right-click Feature Dataset gt New gt Relationship
  Class.
• Relationship Wizard allows you to pick Simple
  relationships (just a link between data) or
  Composite relationships (if you delete the link,
  you delete the data).
• Difference is a bit like that between a relate
  and a join.

29
Relationship Classes

• Defined at the Feature Dataset level.
• Name the relationship between the Classes and
  constraints.
• Highlight Feature and see related features.
• Identify tool
• Highlight Attributes and open Table with related
  Attributes.
• Options gt Related Tables

30
Summary

• Selection
• Can brush in ArcMap selecting Table Data Items
  with mouse and show them in a map, and vice
  versa.
• Aids Data Mining.
• Can select by attributes, location.
• Editing
• Can edit attributes of individual features in
  ArcMap.
• Can sort, edit and calculate new values in Tables
  in ArcMap.

31
Summary

• Relates
• Rather than Join Tables, you can Relate them.
• Saves on storage and allows several people to use
  the same geography for different data.
• Relates usually link a FAT to an external file.
• ArcWorkstation will only relate one or many FAT
  items to one external item. ArcGIS will also
  relate many external items to one FAT item.

32
Displaying Data

• Layouts and map elements.
• Classification.
• Labels.
• Graphics and images.
• Graphs.
• Reports.
• Projections.

33
Layouts and Map Elements

• ArcMap allows us to generate sophisticated
  Documents.
• Document all the Maps, positioning, and other
  elements (plus other stuff like toolbars).
• We can display multiple datasets on the same
  Document.
• To display a Document View gt Layout View
• Layout Colouring, symbology, scales etc.
• Layer image of a type of geographical
  information, e.g. Rivers. References data,
  doesnt store it. Also contains symbology.
• Map Multiple Layers, with legends, etc.
• Data Frame displays Map.
• Active Data Frame the one you can edit in
  Editor view.

34
Object Types

• Layout View

35
Adding Layers

• Drag and drop into Active Data Frame from
  ArcCatalog.
• Add Data Button.
• Right-click and copy / paste.
• Important you realise the difference between a
  Layer and the Data behind it especially when
  Saving.

36
Templates

• If you set up a Layout, and you want to use it on
  other data, you can save it as a Template.
• File gt Save As gt Save as type template
  (.mxt)
• When you hit File gt New it will offer you
  potential Templates, including Normal.mxt.
• To put in your own tab, make a directory in the
  ARCHOME/bin/Templates directory when you Save As

37
Saving in ArcMap

• When you Save in ArcMap you save a Map a
  collection of links to information on Layouts,
  map elements, data etc.
• If you move your map files you can loose that.
• These, therefore, are mainly for display, not
  analysis or exchange.
• You can send people these and all the relevant
  data files. Best thing is to Save relative
  pathnames, and distribute a directory with all
  the files.

38
Moving Layer Files

• You can also save Layers, but they have the same
  problems.
• Right-click Layer gt Save As Layer File
• When they loose datasources, they display a red
  !.
• Could send people the Coverages and let them find
  the datasets using Set Data Source...

39
Transferring Maps

• Best thing is not to.
• Next best is to Export as a Shapefile.
• Finally, if the end person doesnt want to alter
  the Map, you can export as a graphics file
• File gt Export Map
• Types
• BMP Bitmap
• PDF Portable Document Format
• JPEG Joint Photographic Experts Group
• EMF Enhanced Windows Metafiles
• EPS Encapsulated PostScript

40
Adding Map Elements

• Use the Insert menu brings up selector dialogs.

Alter standard looks
41
Symbols

• Under a Layers properties, you can set
  classification display

Note graded colours picked using Table of
Contents.
42
Classification Displays

• Features
• Single feature gets own symbol.
• Categories
• Colour by unique values.
• Quantities
• Colour or size by values on a gradient.
• Multiple Attributes
• Colour on several gradients.

43
Classifications

• Right clicking on a symbol gives options for
• removing classes
• re-ramping colours from the selected one allows
  you to build your own colour ramps
• altering the symbols.
• In some cases you can also exclude values.
• However, well as accepting the divisions given by
  ArcMap you can develop your own.

44
Classification Screen

• Shows histogram, classes and statistics.

45
Classification Schemes

• Manual
• Put them where you want.
• Natural Breaks (Jenks)
• Boundaries put where large jumps in histogram.
• Equal Interval
• Splits the range equally good for top ten
  type analyses.
• Quantile
• Each class has an equal number of features can
  result in similar features being in different
  classes.
• Standard Deviation
• Variation from the mean in terms of SDs good
  for showing patterns or extremes.
• In addition, you can click on, and alter, the
  Break Values. allows you to remove zero or
  missing value numbers.

46
Labels

• Can create a single label.
• In Layer Properties gt Labels gt Label Field pick
  the Attribute you want to use.
• Click the Label button (Draw toolbar) and make
  sure Place label at position clicked is selected.
• Click the feature you want to label.

47
Dynamic Labels

• On the Labels dialog, check the Label Features
  box and pick an Attribute.
• Placement Properties using advanced options
  allows you to select where to label.
• Once generated, they can be turned on or off by
  right-clicking on the Layer and checking Label
  Features.
• As you zoom, labels and symbols resize so they
  look the same. If you want to fix their size
  right-click the Data Frame and select Set
  Reference Scale.

48
Which are displayed?

• ArcMap will try and fit in as many as is
  readable.
• If it becomes crowded, some will disappear.
• Right-click on Data Frame gt Labels to choose
  which order they are dropped and/or how they
  overlap / conflict.
• Can also set the max and min scales at which they
  appear by right-clicking on a Layer. This gives
  the Layer a grey scale-bar icon.

49
Fixing Labels

• Zoom to approximately the right level of
  labelling.
• Right click Layer and select Convert Labels to
  Annotation.

50
Labels to Annotations

• This will convert the labels to text annotations.
• If there is overlap between labels during this
  process a table appears allowing you to
  right-click and add labels that would be
  discarded because of overlapping.

51
Adding Graphics

• The Draw toolbar allows you to add further
  annotations and standard shapes, as well as
  ordering them.
• This allows you to, for example, make a dark
  rectangle and put it behind a Data Frame to make
  a drop shadow.

52
Adding Pictures

• You can also use Insert gt Picture to add images,
  though it can take some zooming to find and
  rescale images.

53
Graphs and Reports

• We can add graphical or textural summaries of our
  Data in the form of
• Graphs
• For example, pie charts, scatter plots, etc.
• Reports
• Lists of Attributes per area / Feature, and
  statistics.

54
Inserting Graphs

• Use Tools gt Graphs gt create to make the Graph
• Follow the graph wizard (very like excel
  charting).
• Right click on the Graph title bar and select
  Show on Layout

55
Adding Reports and Graphs

• Adding Reports is essentially the same process.
• In both cases you can save / export the object so
  you can import them into other Maps.

56
Projections

• ArcMap will take the coordinate system of the
  first Coverage you add, and convert all Layers to
  it for display and editing.
• If it doesnt recognise the Projection
  information it will check to see if the
  coordinates fall between 0 and 360, in which case
  it will assume Lat. and Long.
• If not it will assume x,y.

57
Reprojection

• You can alter a Layers Projection under its
  preferences. This will also tell you the current
  projection.
• If you want to reproject a Coverages datas
  coordinates into another projections system, use
  ArcToolboxs Projection Wizard.

58
Why reproject propaganda

• 1973 Arno Peters introduced a new area
  conserving projection subsequently called the
  Peters Projection.
• Claimed the Mercator projection was used as a
  Cold-War propaganda weapon to increase the size
  of Russian landmass and reduce the needs of the
  South.

Peters
Mercator
59
Why reproject avoid distortions

• To avoid massive distortions, some projections
  have Zones almost distortionless areas of the
  globe that are split from each other by gaps,
  which take up the distortion.
• E.g. Mercator
• If you are dealing with data at the edge of
  Zones, the lines crossing the gaps may not match.
• If you reproject the data at the edge of the
  zones into one or other Zone, it sort of solves
  this problem.
• Note, however, that the distortion in the
  reprojected data increases away from the edge.

60
Why reproject storage and data linking

• Your organisation may store all their data in one
  projection.
• You may have very localised data you need to add
  to a national dataset (usually the distortions on
  local data are small enough the choice doesnt
  matter).
• Distortions can loose data
• use equal area projections for maps that rely on
  showing accurate area quantities.
• Use Mercator projections for maps that rely on
  showing correct distances and directions, e.g.
  navigation.
• NB. Always pay attention to your projection when
  dealing with the Poles, as these are usually
  where the greatest distortions arise.

61
Reprojecting in Arc

• Quite tricky. The secret is to get it done right
  the first time.
• Decide what projection you are going to use when
  making your Coverage.
• Adding it later is difficult.

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Next Lecture

• Spatial Analysis and Networks
• Next Practical
• Tables and Maps