GEOG 400, Advanced GIS, Fall 2020; Week 6 Lecture 1

Transcript

1. GEOG 400: Advanced GIS - Raster Week 6 – Lecture 1 Zonal Raster Operations
2. GEOG 400: Advanced GIS - Raster 1. Local Operations 4. Global Operations 2. Focal Operations 3. Zonal Operations There are four types of raster operations we’ll discuss this week and next: Operations that work on single cell locations one at a time Operations that work on cells within a neighborhood Operations that work on cells within particular zones Operations that work on all cells within the raster at the same time
3. GEOG 400: Advanced GIS - Raster 1. Local Operations 4. Global Operations 2. Focal Operations 3. Zonal Operations There are four types of raster operations we’ll discuss this week and next: Operations that work on single cell locations one at a time Operations that work on cells within a neighborhood Operations that work on cells within particular zones Operations that work on all cells within the raster at the same time
4. 1. Local analyses A spatial/mathematical operation is performed on every single cell, individually, independent of surrounding cells 81 59 2 65 35 50 53 73 82 23 97 47 48 72 39 38 input raster operation [divide by 2] output raster 40.5 29.5 1 32.5 17.5 25 26.5 36.5 41 11.5 48.5 23.5 24 36 19.5 19 There are four types of raster operations we’ll discuss this week and next:
5. 81 59 2 65 35 50 53 73 82 23 97 47 48 72 39 38 input raster operation [mean] output raster 53.6 neighborhood 2. Focal analyses A spatial/mathematical operation is performed on every single cell, individually, based on some pre-defined neighborhood There are four types of raster operations we’ll discuss this week and next:
6. Zonal Operations in ArcGIS • Introduction • We’ve now covered local analyses • Raster analyses where some operation is performed on every cell independent of any other cell • e.g. reclassification, conditional analyses, map algebra
7. Zonal Operations in ArcGIS • Introduction • We’ve now covered local analyses • Raster analyses where some operation is performed on every cell independent of any other cell • e.g. reclassification, conditional analyses, map algebra • We’ve now covered focal analyses • Raster analyses where some operation is performed on every cell based on the cells that surround it in some pre-defined neighborhood size and shape • e.g. focal mean, max, min, range, majority, etc.
8. • Introduction • Let’s tackle zonal analyses • Raster analyses where some operation is performed on every cell within some set of fixed geometric features (zones) of interest 69 54 58 15 37 88 12 38 78 64 59 87 13 88 57 11 18 23 23 13 81 78 73 86 50 31 82 90 31 58 61 77 63 95 80 89 57 30 62 37 53 31 11 62 99 23 23 91 51 input raster input zones output raster 51.7 50.4 50.4 50.4 50.4 50.4 50.4 51.7 51.7 51.7 50.4 50.4 50.4 50.4 51.7 51.7 51.7 53.2 53.2 50.4 50.4 51.7 51.7 53.2 53.2 53.2 63.3 63.3 51.7 53.2 53.2 53.2 53.2 63.3 63.3 53.2 53.2 53.2 53.2 63.3 63.3 63.3 53.2 53.2 53.2 53.2 63.3 63.3 63.3 Zonal Operations in ArcGIS
9. results from analysis only applied to single, target raster cell results from analysis applied to all cells within the zone Zonal Operations in ArcGIS
10. 48 94 12 0 33 49 2 12 5 11 68 25 69 40 32 59 98 70 14 44 22 65 36 92 85 48 94 12 0 33 49 2 12 5 11 68 25 69 40 32 59 98 70 14 44 22 65 36 92 85 FOCAL ZONAL mean mean input neighborhood/zone function output 37.2 37.2 37.2 37.2 37.2 37.2 37.2 37.2 37.2 37.2
11. results from analysis only applied to single, target raster cell results from analysis applied to all cells within the zone Zonal Operations in ArcGIS neighborhood is the same for every cell throughout entire raster zone geometry is not fixed; each can be a different size/shape
12. FOCAL ZONAL Zonal Operations in ArcGIS
13. results from analysis only applied to single, target raster cell results from analysis applied to all cells within the zone Zonal Operations in ArcGIS neighborhood is the same for every cell throughout entire raster zone geometry is not fixed; each can be a different size/shape analysis is performed as a “moving window” – series of overlapping neighborhoods analysis is performed within the fixed zones – no overlap between zones
14. FOCAL ZONAL Zonal Operations in ArcGIS
15. FOCAL ZONAL Zonal Operations in ArcGIS
16. FOCAL ZONAL Zonal Operations in ArcGIS
17. FOCAL ZONAL Zonal Operations in ArcGIS
18. FOCAL ZONAL Zonal Operations in ArcGIS
19. FOCAL ZONAL Zonal Operations in ArcGIS
20. FOCAL ZONAL Zonal Operations in ArcGIS
21. FOCAL ZONAL Zonal Operations in ArcGIS
22. FOCAL ZONAL Zonal Operations in ArcGIS
23. FOCAL ZONAL Zonal Operations in ArcGIS
24. FOCAL ZONAL Zonal Operations in ArcGIS
25. FOCAL ZONAL Zonal Operations in ArcGIS
26. FOCAL ZONAL Zonal Operations in ArcGIS
27. FOCAL ZONAL Zonal Operations in ArcGIS
28. FOCAL ZONAL Zonal Operations in ArcGIS
29. FOCAL ZONAL Zonal Operations in ArcGIS
30. results from analysis only applied to single, target raster cell results from analysis applied to all cells within the zone Zonal Operations in ArcGIS neighborhood is the same for every cell throughout entire raster zone geometry is not fixed; each can be a different size/shape analysis is performed as a “moving window” – series of overlapping neighborhoods analysis is performed within the fixed zones – no overlap between zones analysis performed based on some pre-defined area all of the same statistical methods (mean, median, SD, mode, range, max, min, sum, majority, minority, variety)
31. • Zonal operations • In ArcGIS, the zonal operations can be found in the Zonal toolbox • The main tool of interest is the Zonal Statistics tool Zonal Operations in ArcGIS
32. • Zonal operations • Let’s say you want to buy a piece of property in La Plata County • Tax parcel must possess… • A majority of forested land • A mean elevation above 8000’ • A maximum slope of 10° • At least 5 acres of land you want to buy this Zonal Operations in ArcGIS
33. • Zonal operations • Step 1. Determine majority land cover by tax parcel Zonal Operations in ArcGIS
34. • Zonal operations • Step 1. Determine majority land cover by tax parcel Zonal Operations in ArcGIS
35. • Zonal operations • Step 1. Determine majority land cover by tax parcel Zonal Operations in ArcGIS
36. • Zonal operations • Step 1. Determine majority land cover by tax parcel Zonal Operations in ArcGIS
37. • Zonal operations • Step 1. Determine majority land cover by tax parcel Zonal Operations in ArcGIS
38. • Zonal operations • Step 1. Determine majority land cover by tax parcel • If you would prefer the result of your zonal analysis to be in vector format you can… 1. Perform a raster to vector conversion 2. Use the “Zonal Statistics as Table” tool, followed by a “Join” to link back to the original vector dataset Zonal Operations in ArcGIS
39. • Zonal operations • Raster to vector conversion option • This process presents challenges… original vector dataset raster-to-vector converted dataset Zonal Operations in ArcGIS
40. • Zonal operations • “Zonal Statistics as Table” + “Join” option • Better approach Zonal Operations in ArcGIS
41. • Zonal operations • “Zonal Statistics as Table” + “Join” option • Better approach • Results… Much nicer. Zonal Operations in ArcGIS
42. • Zonal operations • “Zonal Statistics as Table” + “Join” option • Better approach • Results… Much nicer. sidenote: notice all of the “NoData” values (empty parcels) – this is because the raster resolution (NLCD = 30m) is larger than the parcel, therefore no value is given… something to keep in mind! Zonal Operations in ArcGIS
43. • Zonal operations • Step 2. Determine mean elevation by tax parcel Zonal Operations in ArcGIS
44. • Zonal operations • Step 2. Determine mean elevation by tax parcel Zonal Operations in ArcGIS
45. • Zonal operations • Step 3. Determine max slope by tax parcel Zonal Operations in ArcGIS
46. • Zonal operations • Step 3. Determine max slope by tax parcel Zonal Operations in ArcGIS
47. • Zonal operations • Step 4. Determine size of parcels Zonal Operations in ArcGIS
48. • Zonal operations • Step 5. Perform some conditional and logical analyses using the Raster Calculator Zonal Operations in ArcGIS
49. • Zonal operations • And the results! Zonal Operations in ArcGIS