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GIS Lecture 8 Spatial Data Processing. Outline. Extracting Features by Attributes Location Proximities Geoprocessing Tools Model Builder. Extracting Features. Attribute Query Extraction. You have tracts for state but want one county only. Attribute Query Extraction.

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GIS Lecture 8

Spatial Data Processing

  • Extracting Features by Attributes
  • Location Proximities
  • Geoprocessing Tools
  • Model Builder
attribute query extraction
Attribute Query Extraction
  • You have tracts for state but want one county only
attribute query extraction5
Attribute Query Extraction
  • Select tracts by County ID
export selected features
Export Selected Features
  • Right-click to export selected features
select by location
Select by Location
  • Identify spatial relationships between layers
  • Finds features that are within another layer.

Input: County Census TractsCan’t use Select By Attributes

Output:City tracts only

select by location10
Select by Location
  • Select feature to extract tracts to (city outline)
select by location11
Select by Location
  • Selection, Select By Location
other select by location queries
Other Select by Location Queries
  • Toxic release sites within 1 mile of a river
other select by location queries14
Other Select by Location Queries
  • Points near points
  • Schools within ½ mile of polluting companies
other select by location queries15
Other Select by Location Queries

Polygons intersecting lines

Municipalities that intersect Interstates

other select by location queries16
Other Select by Location Queries


other select by location queries17
Other Select by Location Queries
  • Buildings whose centers are in emergency zones
geoprocessing tools
Geoprocessing Tools
  • GIS Operation to manipulate data
  • Typically take input data sets, manipulate, and produce output data sets
  • Often use multiple data sets
geoprocessing tools20
Geoprocessing Tools
  • Clip
  • Dissolve
  • Intersect
  • Union
  • Append

“Cookie cutter” to select features


line arc clipping
Line (Arc) Clipping

Input layer - Streets

Clip layer – Central Business District (selected)

Output layer - Streets within Central Business District

difference between clipping and select by location
Difference Between Clipping and Select by Location

Clip: Clean “cut”

Select by Location:Dangle edges


Aggregates items that have the same value

# Item

1 C

2 R

3 C

4 I

dissolve example
Dissolve Example
  • You have states but need regions
dissolve functions
Dissolve Functions
  • ArcToolBox or Command Line Window
dissolve field
Dissolve Field

Field with a common value for each feature (e.g. Sub_Region)

statistics field
Statistics Field

Aggregated field can be summarized using a statistics type (i.e. state population can be aggregated by population for each region)

  • Appends features together
append streets
Append Streets
  • Separate street layers for neighborhoods
append streets37
Append Streets
  • Choose both street layers to append
resultant layer
Resultant Layer
  • One street layer with all records and field items
  • Use Union when you want to overlay two polygon layers so that the resulting output layer
  • a) has the combined attribute data of the polygons in the two inputs, and
  • b) contains all the polygons from the inputs, whether or not they overlap.

Start with Pittsburgh ZIP codes and Neighborhoods

  • Attributes tables contain different data

Union neighborhoods and ZIP Codes to include the zip on each neighborhood polygon

  • Result: Polygons are unioned with same information
  • Tips: Same Projections, Order of Layers
  • Use Intersect when you want to overlay a layer with the polygons in another layer so that the resulting output layer
  • - has the combined attribute data of the features in the two inputs, and
  • - only contains features that fall within the spatial extent of the overlay polygons

Flood zones that intersect buildings


Result is only building polygons that intersect floodzones with combined data fields

model builder50
Model Builder
  • Workflow processes can be complicated
  • Automates and strings functions together
model builder51
Model Builder
  • Problem:
    • You have census tracts from a state with population data but only want population for neighborhoods in a small region
  • Solution:
    • Use Model Builder functions to clip census tracts and union to aggregate data to neighborhoods
model builder example
Model Builder Example

Begin with census tracts for the state of Pennsylvania

model builder example53
Model Builder Example
  • Clip only tracts whose centers are located within Pittsburgh neighborhoods
  • Union the census tracts and neighborhoods
model builder example54
Model Builder Example
  • Run the model…
model builder example55
Model Builder Example

Display and query the results


Extracting Features

    • Attribute Queries
    • Select by Location
  • Converting Shapefiles
  • Geoprocessing Tools
    • Clip
    • Dissolve
    • Union
    • Intersect
    • Append
  • Model Builder