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Data Storage and Processing

Data Storage and Processing. GIS Topics and Applications. GIS Models Over Time. Simple Representation CAD model Data Analysis Raster model Data Collection Vector model Relational and Rules Object model. Objects.

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Data Storage and Processing

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  1. Data Storage and Processing GIS Topics and Applications

  2. GIS Models Over Time • Simple Representation • CAD model • Data Analysis • Raster model • Data Collection • Vector model • Relational and Rules • Object model

  3. Objects • GIS Features as Objects is a recent method of representing aspects of the real-world in GIS • Example of the shift from specialty data to DBMS that are spatially-aware • Non-planar, temporally shifting, topologically linked, rule-based actions

  4. Vector Geometry as Objects • Parcels • Planar geometries with attribute information • Parcels as objects in a Cadastral “carpet” • Objects with topology rules (“don’t overlap, unless”) • Members of “regional” features (zoning, municipality) • Composed of surveyed parts (COGO, benchmarks) • Keys that link to attribute tables (owner(s), assessments, plans, etc)

  5. survey (COGO) parcels zones Cadastre Example benchmark

  6. Attributes as Objects • Not only can multiple sets of geospatial features interact with rules, the attributes can be linked with one another, with their own set of rules and actions • Ownership record linked to GIS parcel • Search on multiple owners, records • Removal of parcel warns about “orphan” owner • Functions that can be performed by GIS analyst can be embedded in the actual database

  7. Manipulating Vector Mode Databases

  8. Common Operations Selection by Attributes or Location Dissolve Append Clip Intersect Union

  9. Select by Attributes • Create WHERE clauses that match a subset of the features in a vector dataset. • WHERE clauses are a part of Structured Query Language (SQL) • Analogous to "Find" in some other software. • Match all records where… • "COUNTY" = 'Gloucester' • NOT "TYPE" = 'Wetlands' • "POP2000" > 100000

  10. Select by Location • Proximity or overlay based on features in one layer and features in another layer or the same layer. • Several methods to compare proximity & overlay • Distance from • Touching (on edge) • Contains or Within • Partial Overlaps • Exact Matches

  11. Dissolve

  12. Dissolve Features Input Output

  13. Append

  14. Layers to Append Input Layer 1 Input Layer 2 Appended Layers Overlapping Polygons/Polylines are preserved!

  15. Clip

  16. Input Layer & Clipping Layer Clip Polygon Input Layer Clipped Features Output Layer

  17. Intersect

  18. Intersection Where are the Road segments that are in flood prone areas. Select flood prone from Input Layer 1 Intersect roads and flood prone [Layer 2].

  19. Input Layer 2 Roads Intersect Features Input Layer 1 Stream Flood Prone No Flood Panel 1

  20. Intersect Features Input Layer 1 Stream Flood Prone Question: where are the road segments that pass through flood prone areas? No Flood Input Layer 2 Roads Panel 1

  21. Intersect Features Input Layer 1 Stream Flood Prone No Flood Select flood prone areas and then intersect Input Layer 1 with Layer 2 Roads. Input Layer 2 Roads Panel 2

  22. Intersect Features Output Layer Roads Flood Prone Study Area Roads that pass through flood prone areas. Attributes of both layers maintained in table. Length of roads in flood areas becomes attribute Panel 3

  23. Intersection Where are the places that are residential and flood prone. Select flood prone from Input Layer 1 Select residential from Input Layer 2 Intersect

  24. Intersect Features Input Layer 1 Stream Flood Prone No Flood Panel 1

  25. Intersect Features Input Layer 2 Residential Commercial Industry Panel 2 Open space

  26. Intersect Features Input Layer 1 Stream Flood Prone No Flood Input Layer 2 Residential Commercial Industry Panel 3 Open space

  27. Intersect Features Output Layer Residential & Flood Prone Extent Panel 4

  28. Panel 2 Panel 1 Panel 4 Panel 3

  29. Union

  30. Panel 1 Agricultural Land Use Corn Green Beans Tomatoes Wheat

  31. Panel 2 Soil Quality Poor Fair Good Excellent

  32. Panel 3 Agricultural Land Use Corn Green Beans & Poor Corn &Poor Green Beans Tomatoes Corn & Excellent Green Beans & Fair Wheat Tomatoes & Fair Wheat & Excellent Soil Quality Poor Wheat & Good Fair Tomatoes & Good Good Excellent

  33. Let’s See How It Works

  34. Dissolve

  35. 1. Right Click 2. Click to select. Dissolve Operation

  36. 2. Click to open Add Field dialog 1. Click to open menu AddFieldforDissolve

  37. Type a name and click OK NameandTypeofFieldforDissolve

  38. Table with Code Field Resultingfield

  39. Double Click Click Click DotheDissolve

  40. 1 2 3 4 DissolveDialog

  41. Dissolve

  42. Click Double Click Click AppendOperation

  43. 1 2 3 4 AppendDialog

  44. Append Two layers before append One layer after append

  45. Click Click Double Click ClipOperation

  46. 1 2 3 ClipDialog

  47. Clipping Roads before clipping Roads after Clipping

  48. Intersection

  49. Intersection Procedure • Where are the areas that are residential in land use and flood prone? • Select flood prone areas from flood prone layer • Select residential areas from land use layer • Do intersection

  50. Intersect

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