gis lecture 8 spatial data processing

GIS 1

GIS Lecture 8Spatial Data Processing

GIS 2

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

GIS 3

Extracting Features

GIS 4

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

GIS 5

Attribute Query Extraction•Select tracts by County ID

GIS 6

Export Selected Features Right-click to export selected features

GIS 7

Add Exported Layer

GIS 8

Location Proximities

GIS 9

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

GIS 10

Select by Location Select feature to extract tracts to (city outline)

GIS 11

Select by Location Selection, Select By Location

GIS 12

Export Selection and Add Layer

GIS 13

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

GIS 14

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

GIS 15

Other Select by Location QueriesPolygons intersecting linesMunicipalities that intersect Interstates

GIS 16

Other Select by Location QueriesLines intersecting polygons

GIS 17

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

GIS 18

Geoprocessing Tools OverviewClipping Features

GIS 19

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

GIS 20

Geoprocessing Tools Clip Dissolve Intersect Union Append

GIS 21

Clipping Features

GIS 22

Clip“Cookie cutter” to select features

=

GIS 23

Clipping Features (Points, Lines, Polygons)

X Y Z

=

=

=

GIS 24

Line (Arc) Clipping Input layer - Streets

Clip layer – Central Business District (selected)

Output layer - Streets within Central Business District

GIS 25

Clip Geoprocessing Tool

GIS 26

Difference Between Clipping and Select by LocationClip: Clean “cut”

Select by Location:Dangle edges

GIS 27

Dissolving Features

GIS 28

Dissolve Aggregates items that have the same value

#

Item1

C2

R3

C4

I

GIS 29

Dissolve Example You have states but need regions

GIS 30

Dissolve Functions ArcToolBox or Command Line Window

GIS 31

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

GIS 32

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

GIS 33

Resultant Dissolved Regions Layer

GIS 34

Appending Features

GIS 35

Append Appends features together

GIS 36

Append Streets Separate street layers for neighborhoods

GIS 37

Append Streets Choose both street layers to append

GIS 38

Resultant Layer One street layer with all records and field items

GIS 39

Union Features

GIS 40

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 41

UnionStart with Pittsburgh ZIP codes and Neighborhoods

GIS 42

Union Attributes tables contain different data

GIS 43

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

GIS 44

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

GIS 45

Intersecting Features

GIS 46

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 47

IntersectFlood zones that intersect buildings

GIS 48

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

GIS 49

Model Builder

GIS 50

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

GIS 51

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 52

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

GIS 53

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

GIS 54

Model Builder Example Run the model…

GIS 55

Model Builder ExampleDisplay and query the results

GIS 56

Summary Extracting Features•Attribute Queries•Select by Location

Converting Shapefiles Geoprocessing Tools•Clip•Dissolve•Union•Intersect•Append

Model Builder