GIS Lecture 8 Spatial Data Processing GIS 1

GIS Lecture 8 Spatial Data Processing GIS 1

Outline • Extracting Features by Attributes • Location Proximities • Geoprocessing Tools • Model Builder GIS 2

Extracting Features GIS 3

Attribute Query Extraction • You have tracts for state but want one county only GIS 4

Attribute Query Extraction • Select tracts by County ID GIS 5

Export Selected Features Right-click to export selected features GIS 6

Add Exported Layer GIS 7

Location Proximities GIS 8

Select by Location • Identify spatial relationships between layers • Finds features that are within another layer. Input: County Census Tracts Can’t use Select By Attributes Output: City tracts only GIS 9

Select by Location Select feature to extracts to (city outline) GIS 10

Select by Location Selection, Select By Location GIS 11

Export Selection and Add Layer GIS 12

Other Select by Location Queries • Toxic release sites within 1 mile of a river GIS 13

Other Select by Location Queries • Points near points • Schools within ½ mile of polluting companies GIS 14

Other Select by Location Queries Polygons intersecting lines Municipalities that intersect Interstates GIS 15

Other Select by Location Queries Lines intersecting polygons GIS 16

Other Select by Location Queries • Buildings whose centers are in emergency zones GIS 17

Geoprocessing Tools Overview Clipping Features GIS 18

Geoprocessing Tools • GIS Operation to manipulate data • Typically take input data sets, manipulate, and produce output data sets • Often use multiple data sets GIS 19

Geoprocessing Tools Clip Dissolve Intersect Union Append GIS 20

Clipping Features GIS 21

Clip “Cookie cutter” to select features = GIS 22

Clipping Features (Points, Lines, Polygons) X Y Z = = = GIS 23

Line (Arc) Clipping Input layer - Streets Clip layer – Central Business District (selected) Output layer - Streets within Central Business District GIS 24

Clip Geoprocessing Tool GIS 25

Difference Between Clipping and Select by Location Clip: Clean “cut” Select by Location: Dangle edges GIS 26

Dissolving Features GIS 27

Dissolve Aggregates items that have the same value # Item 1 C 2 R 3 C 4 I GIS 28

Dissolve Example You have states but need regions GIS 29

Dissolve Functions Arc. Tool. Box or Command Line Window GIS 30

Dissolve Field with a common value for each feature (e. g. Sub_Region) GIS 31

Statistics Field Aggregated field can be summarized using a statistics type (i. e. state population can be aggregated by population for each region) GIS 32

Resultant Dissolved Regions Layer GIS 33

Appending Features GIS 34

Appends features together GIS 35

Append Streets Separate street layers for neighborhoods GIS 36

Append Streets Choose both street layers to append GIS 37

Resultant Layer One street layer with all records and field items GIS 38

Union Features GIS 39

Union 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. GIS 40

Union Start with Pittsburgh ZIP codes and Neighborhoods GIS 41

Union Attributes tables contain different data GIS 42

Union neighborhoods and ZIP Codes to include the zip on each neighborhood polygon GIS 43

Union Result: Polygons are unioned with same information Tips: Same Projections, Order of Layers GIS 44

Intersecting Features GIS 45

Intersect 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 GIS 46

Intersect Flood zones that intersect buildings GIS 47

Intersect Result is only building polygons that intersect floodzones with combined data fields GIS 48

Model Builder GIS 49

Model Builder • Workflow processes can be complicated • Automates and strings functions together GIS 50

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 GIS 51

Model Builder Example Begin with census tracts for the state of Pennsylvania GIS 52

Model Builder Example • Clip only tracts whose centers are located within Pittsburgh neighborhoods • Union the census tracts and neighborhoods GIS 53

Model Builder Example Run the model… GIS 54

Model Builder Example Display and query the results GIS 55

Summary Extracting Features • Attribute Queries • Select by Location Converting Shapefiles Geoprocessing Tools • Clip • Dissolve • Union • Intersect • Append Model Builder GIS 56