Overview

1
Overview

• Unioning polygons
• Merging polygons
• Intersecting polygons
• Clipping polygons
• Adding attributes
• Undoing edits
• Saving edits_

• Digitizing
• Creating vector data sets
• Converting to feature class
• Creating new datasets
• Snapping
• Altering the shape of lines and polygons
• Splitting features

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Digitizing

• most common legacy method of getting data into
  a GIS

• tedious detail-oriented work_

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Digitizing tablet

• How the digitizing tablet works

coordinates are placed in database
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Creating vector data sets

• ArcGIS supports creation of vector data sets
  (shapefile geodatabase feature class)
• Point
• Line
• Polygon
• Complete creation editing of data sets is
  supported (feature classes)
• Coordinate data
• Attribute data_

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Converting to feature class

• Any supported vector data set can be converted to
  feature class

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Converting to feature class

• Any supported vector data set can be converted to
  feature class

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Converting to feature class

• Selected sets are converted

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Creating new datasets

• New datasets can be created from scratch in
  ArcCatalog
• decide in advance what feature type to represent
  your data

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Creating new datasets

• New datasets can be created from scratch in
  ArcCatalog
• specify coordinate system

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Creating new datasetsHeads-up digitizing

• New datasets can be created from scratch

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Creating new datasets

• New datasets can be created from scratch

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Creating new datasets

• New features can be created from tracing existing
  features

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Snapping

• Snapping controls
• how features align during creation/editing
• connections of lines (node placement)
• completion of polygons
• avoid overshoots/undershoots
• avoid slivers or gaps

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Snapping

• Snapping behavior controlled by the Snapping
  Environment dialog

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Snapping
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Snapping options

• Interactive snapping options
• Snap to an existing vertex
• Snap to an existing line segment or polygon edge
• Snap to an intersection of two or more lines
• Snap to an existing line endpoint
• Snapping can be layer-to-layer_

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Altering the shape of lines and polygons
topological editing
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Altering the shape of lines and polygons
non-topological editing
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Splitting (cutting) polygons
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Splitting lines
split tool
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Splitting features

• Geodatabase splitting policies
• Attributes are handled by policies
• Duplicate values in new records are copied from
  the parent record
• Geometry property (e.g., area, perimeter, length)
  automatically handled
• Geometry ratio (e.g., population)_

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Splitting features

• Attribute splitting (for geodatabase feature
  classes) is handled by policies

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Merging polygons
select multiple polygons from the same layer
original polygons are merged into a single new
polygon
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Merging polygons

• Attributes are handled by rules in the same way
  as splitting

image from ESRI
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Unioning polygons

• similar to merge, but can combine features from gt
  1 layer

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Intersecting polygons

• like mathematical intersection

• spatial area as the "set" for intersection
• common areas are preserved

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Intersecting polygons
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Clipping polygons
when overlapping polygons are combined, an
"erase" occurs
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Clipping polygons
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Adding attributes

• Attributes need to be defined for new datasets
• Fields are added define
• field name
• data type
• width
• decimal precision

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Adding attributes

• Adding defining fields

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Adding attributes

• After fields are added, attributes can be updated

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Undoing edits

• Edits can be undone in reverse order
• Edits can be undone up to the previous save (or
  creation)
• Once a datasets changes are saved, edits cannot
  be undone_

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Saving edits

• Save EARLY and OFTEN
• You are prompted to save edits when
• Dataset is closed for editing
• Another dataset is opened for editing
• Document is saved or closed
• ArcGIS is closed_