Introduction to GIS

1
Introduction to GIS

• Manipulating
• feature classes

2
Class Discussion

• Edit feature classes
• Change part of feature class
• Modify feature classes
• Snapping
• Create new feature classes
• Creating event feature classes

3
Editing Feature Classes

• Make changes to existing shape field
• These changes will be permanent
• Use copy of original feature class
• Insert/Delete/Change vertices
• Does NOT alter related attribute data

4
Changing Existing Features

• Start Editing
• Need editor tool bar
• Select feature class to change
• Specify Task and Target
• Highlight vertices
• Edit
• Save changes

5
Add editor tool bar and start editing
6
Select FC to edit
7
Modify Features
Task identifies what function will be performed
Target identifies which feature class the
function will be performed on
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Select feature to edit
Click to show vertices
9
Move a vertex
Click to select then drag to new location
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Delete and finish options
Right click while hovering over vertex and make
selection
11
Add Vertex
Right click while hovering over section of line
to insert vertex
12
Set Snapping
Identify what you want to snap to
13
Determine Snapping tolerance
14
Create Own feature class

• Define parameters
• Identify format of data to be entered
• Digitize - definition of geographic location
• Enter Data

15
New Feature Classes should be in a PGD
Start process in ArcCatelog
Create PGD if none exists
Create New-Feature Class
16
Navigate through Dialog Boxes
1.
2.
17
Define shape field and parameters
Click Geometry to open parameter box and identify
format of geography (point, line, polygon)
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Define all other fields
19
Add new blank FC to ArcMap
20
Start Editing-Create New Features-Apply
Snapping-Use Draw Tool
1.
2.
4.
3.
21
Digitizing Polygon
Click
Click
Start-Click
End-Double Click
To end your new polygon either double click or
right click and select finish sketch
22
Snapping to Adjacent Polygons
Change your task to Auto-complete Polygon
Overshoot your start point and your end point
23
Tracing existing polygons

• Combination of cursor functions
• Snap to existing new polygon
• Snap to existing border of different feature class

24
Use trace and Auto-complete
To create a polygon that will snap to both the
new polygon and the existing one from another
feature class.
New
Existing
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Logic to create snapped traced poly

• Make sure snapping is set for feature class to
  trace
• Start with cursor as sketch tool
• Start with task Auto-Complete
• Start with old border you want to trace
  selected (blue)
• Overshoot starting digitization point
• Create vertex at line to trace
• Change cursor to trace tool
• Trace border to snap to
• Create vertex at end of line you are tracing
• Change cursor to sketch tool
• Overshoot ending point and finish sketch

26
Snapping is set, trace border is selected
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Overshoot to start, vertex at trace border,
change to trace tool
Click
Click
28
Follow border to snap to, create vertex at end of
trace area, change back to sketch tool
Click
No clicks, just follow the line
29
Overshoot back into adjacent poly
Result is polygon that is snapped to both polygons
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Resulting Attribute Table
Can add fields and other data to new table
31
Add data to table
32
Event feature classes

• Creating a separate feature class for special
  occurrences
• Does not have to be the same shape

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Event feature class Options

• Point or line events
• Add X,Y data as event feature class
• GPS points
• Other Lat/Long information, but must be in
  decimal degrees

34
Requires table with spatial event information

• Create or load table with latitude and longitude
  information in decimal degrees
• Tables made for decimals must be created using
  the float format (not integer or text)
• Populate the table if necessary
• Spatial data and any other attribute information

35
Convert table to feature class
No Shape Field
X_Coordinates are Longitude
Y_Coordinates are Latitude
36
Complete Dialog box
Which table has the Event data
X/Y Coordinate fields are prompted, but check to
make sure you have your lefts and rights correct
37
New feature class from events
38

• Questions and Demonstration