1. GIS Lecture 8
Spatial Data Processing

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

3. Extracting Features

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

5. Attribute Query Extraction
Select tracts by County ID

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

7. Add Exported Layer

8. Location Proximities

9. 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

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

11. Select by Location
Selection, Select By Location

12. Export Selection and Add Layer

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

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

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

16. Other Select by Location Queries
Lines intersecting polygons

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

18. Geoprocessing Tools Overview Clipping Features

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

20. Geoprocessing Tools
Clip
Dissolve
Intersect
Union
Append

21. Clipping Features

22. Clip
“Cookie cutter” to select features =

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

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

25. Clip Geoprocessing Tool

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

27. Dissolving Features

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

29. Dissolve Example
You have states but need regions

30. Dissolve Functions
ArcToolBox or Command Line Window

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

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

33. Resultant Dissolved Regions Layer

34. Appending Features

35. Append
Appends features together

36. Append Streets
Separate street layers for neighborhoods

37. Append Streets
Choose both street layers to append

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

39. Union Features

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.

41. Union
Start with Pittsburgh ZIP codes and Neighborhoods

42. Union
Attributes tables contain different data

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

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

45. Intersecting Features

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

47. Intersect
Flood zones that intersect buildings

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

49. Model Builder

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

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

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

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

54. Model Builder Example
Run the model…

55. Model Builder Example
Display and query the results

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