Introduction to Geographic Information Systems Fall 2013 (INF 385T-28620) Dr. David Arctur Research Fellow, Adjunct Faculty University of Texas at Austin Lecture 6 October 3, 2013 Spatial Data and Geoprocessing

Outline  Attribute extraction  Feature location extraction  Location proximities  Geoprocessing tools  ModelBuilder 2 INF385T(28620) – Fall 2013 – Lecture 6

ATTRIBUTE EXTRACTION Lecture 6 3 INF385T(28620) – Fall 2013 – Lecture 6

Attribute query extraction You have tracts for an entire state, but want tracts for one county only INF385T(28620) – Fall 2013 – Lecture 6 4

Attribute query extraction  Select tracts by County FIPS ID  Cook County = INF385T(28620) – Fall 2013 – Lecture 6

Attribute query extraction  Cook County tracts selected  Export to new feature class or shapefile 6 INF385T(28620) – Fall 2013 – Lecture 6

Export selected features  Right-click to export selected features 7 INF385T(28620) – Fall 2013 – Lecture 6

Add new layer  Cook County tracts 8 INF385T(28620) – Fall 2013 – Lecture 6

FEATURE LOCATION EXTRACTION Lecture 6 9 INF385T(28620) – Fall 2013 – Lecture 6

Select by location  Powerful function unique to GIS  Identify spatial relationships between layers  Finds features that are within another layer 10 INF385T(28620) – Fall 2013 – Lecture 6

Select by location  Have Cook County census tracts but want City of Chicago only  Can’t use Select By Attributes  No attribute for Chicago  Use “Municipality” layer  City of Chicago is a municipality within Cook County 11 INF385T(28620) – Fall 2013 – Lecture 6

Select by location  Select “Chicago” from municipalities layer 12 INF385T(28620) – Fall 2013 – Lecture 6

Select by location  Selection, select by location 13 INF385T(28620) – Fall 2013 – Lecture 6

Export selected features 14 INF385T(28620) – Fall 2013 – Lecture 6

LOCATION PROXIMITIES Lecture 6 15 INF385T(28620) – Fall 2013 – Lecture 6

Points near polygons  Health officials want to know polluting companies near water features 16 INF385T(28620) – Fall 2013 – Lecture 6

Points near points  School officials want to know what schools are near polluting companies INF385T(28620) – Fall 2013 – Lecture 6 17

Polygons intersecting lines  Transportation planner wants to know what neighborhoods are affected by construction project on major highway INF385T(28620) – Fall 2013 – Lecture 6 18

Lines intersecting polygons  Public works official wants to know what streets or sidewalks will be affected by potential floods 19 INF385T(28620) – Fall 2013 – Lecture 6

Polygons completely within polygons  City planners want to know what buildings are completely within a zoning area. INF385T(28620) – Fall 2013 – Lecture 6 20

GEOPROCESSING TOOLS Lecture 6 21 INF385T(28620) – Fall 2013 – Lecture 6

Geoprocessing overview  GIS operations to manipulate data  Typically take input datasets, manipulate, and produce output datasets  Often use multiple datasets 22 INF385T(28620) – Fall 2013 – Lecture 6

Common geoprocessing tools  Analysis  Extract – clip  Overlay – intersect and union  Data management  Generalization – dissolve  General  append  merge 23 INF385T(28620) – Fall 2013 – Lecture 6

Accessing tools  Geoprocessing menu 24 INF385T(28620) – Fall 2013 – Lecture 6

Accessing tools  ArcToolbox 25 INF385T(28620) – Fall 2013 – Lecture 6

Accessing tools  Search window 26 INF385T(28620) – Fall 2013 – Lecture 6

Clip vs. Select By Location  Clip  Clean edges  Looks good  Select By Location  Dangling edges  Better for geocoding (chapter 8) 27 INF385T(28620) – Fall 2013 – Lecture 6

Dissolve  Combines adjacent polygons to create new, larger polygons  Uses common field value to remove interior lines within each polygon, forming the new polygons  Aggregate (sums) data while dissolving 28 INF385T(28620) – Fall 2013 – Lecture 6

Dissolve  Create regions using US states  Use SUB_REGION field to dissolve  Sum population 29 INF385T(28620) – Fall 2013 – Lecture 6

Dissolve INF385T(28620) – Fall 2013 – Lecture 6 30

Dissolve results  States dissolved to form regions  Population summed for each region 31 INF385T(28620) – Fall 2013 – Lecture 6

Append  Appends one or more datasets into an existing dataset  Features must be of the same type  Input datasets may overlap one another and/or the target dataset  TEST option: field definitions of the feature classes must be the same and in the same order for all appended features  NO TEST option: Input features schemas do not have to match the target feature classes’ schema INF385T(28620) – Fall 2013 – Lecture 6 32

Append  DuPage and Cook County are combining public works and need a new single street centerline file. 33 INF385T(28620) – Fall 2013 – Lecture 6

Append  Append will add DuPage streets to Cook County streets INF385T(28620) – Fall 2013 – Lecture 6 34

Resultant layer  One street layer (Cook County) with all records and field items 35 INF385T(28620) – Fall 2013 – Lecture 6

Merge  Combines multiple input datasets of the same data type into a single, new output dataset  Illinois campaign manager needs a single voting district map but wants to preserve the original layers INF385T(28620) – Fall 2013 – Lecture 6 36

Merge INF385T(28620) – Fall 2013 – Lecture 6 37

Resultant layer  New voting district layer 38 INF385T(28620) – Fall 2013 – Lecture 6

Union  Overlays two polygon layers  Resulting output layer has combined attribute data of the two inputs  Contains all the polygons from the inputs, whether or not they overlap INF385T(28620) – Fall 2013 – Lecture 6 39

Union  Neighborhoods and ZIP Codes INF385T(28620) – Fall 2013 – Lecture 6 40

Union INF385T(28620) – Fall 2013 – Lecture 6 41

Union  Better describes characteristics of a neighborhood  Central business district vs INF385T(28620) – Fall 2013 – Lecture 6 42

Union  Attributes tables contain different fields and data 43 INF385T(28620) – Fall 2013 – Lecture 6

Union results INF385T(28620) – Fall 2013 – Lecture 6  New polygons with combined data 44

Union vs. Merge vs. Dissolve 45 INF385T(28620) – Fall 2013 – Lecture 6 Operation# Input Feature Classes Change in Geometry Schema Restrictions UnionMultipleCombines all input geometries Includes all fields from all input feature classes; input tables do not have to be identical MergeMultipleCombines all input geometries Input tables must be identical; retains one set of attributes DissolveSingleCombines feature geometries based on shared attribute values N/A – single feature class schema

Intersect  Computes a geometric intersection of the input features  Features (or portions of features that overlap in all layers and/or feature classes) will be written to the output feature class  Inputs can have different geometry types INF385T(28620) – Fall 2013 – Lecture 6 46

Intersect  City manager needs to know what buildings intersect flood zones and wants the flood data attached to each intersecting building INF385T(28620) – Fall 2013 – Lecture 6 47

Intersect INF385T(28620) – Fall 2013 – Lecture 6 48

Intersect result  Only building polygons that intersect flood zones with combined data fields INF385T(28620) – Fall 2013 – Lecture 6 49

MODELBUILDER Lecture 6 50 INF385T(28620) – Fall 2013 – Lecture 6

ModelBuilder overview  Models automate and string tools together  Example: You have census tracts for a county and want to create neighborhoods for a city  Some steps are needed to create neighborhoods  Join a crosswalk table to the tracts map layer  Dissolve tracts to create neighborhoods using the dissolve column in the crosswalk  Remove the join so that the model can be rerun if necessary  You run the model for this workflow with one click of a button 51 INF385T(28620) – Fall 2013 – Lecture 6

Starting map  TIGER census tracts and municipalities INF385T(28620) – Fall 2013 – Lecture 6 52

Final map  Tracts dissolved to create neighborhoods INF385T(28620) – Fall 2013 – Lecture 6 53

Crosswalk table  Neighborhood names are not included with the census tracts, so a crosswalk table was created with the name of neighborhood for each census tract  Some neighborhoods are made of multiple tracts INF385T(28620) – Fall 2013 – Lecture 6 54

Set geoprocessing options  Geoprocessing > Geoprocessing Options INF385T(28620) – Fall 2013 – Lecture 6 55

Create a new toolbox  Catalog INF385T(28620) – Fall 2013 – Lecture 6 56

Create a new model  Right-click Toolbox > New > Model INF385T(28620) – Fall 2013 – Lecture 6 57

Add tool to model  Add Join tool  To join crosswalk table to tracts… INF385T(28620) – Fall 2013 – Lecture 6 58

Set parameter for Join tool  Joins crosswalk table to census tracts INF385T(28620) – Fall 2013 – Lecture 6 59

Model steps INF385T(28620) – Fall 2013 – Lecture 6  Add join  Dissolve  Remove join 60

Finished model INF385T(28620) – Fall 2013 – Lecture 6 61

Summary  Attribute extraction  Feature location extraction  Location proximities  Geoprocessing tools  ModelBuilder 62 INF385T(28620) – Fall 2013 – Lecture 6