GIS Lecture 8 Spatial Data Processing

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 TractsCan’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 Linesintersectingpolygons

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

18. Geoprocessing Tools OverviewClipping 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 4 I

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