Data Storage and Processing
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The document describes various models and operations used in GIS, including vector, raster, object models and common vector analysis operations such as selection, dissolve, append, clip, intersect, and union. It provides examples of how each operation works and the input and output layers involved. Key points covered include how topology is maintained in vector models, attributes can be linked as objects, and how selection and overlay operations can be used to analyze spatial relationships between layers.
![IntersectionWhere are the Road segments that are in flood prone areas.Select flood prone from Input Layer 1Intersect roads and flood prone [Layer 2].](https://image.slidesharecdn.com/gislecture03-110131212921-phpapp01/85/Data-Storage-and-Processing-24-320.jpg)
Data Storage and Processing
- 1. Data Storage and ProcessingGIS Topics and Applications
- 2. GIS Models Over TimeSimple RepresentationCAD modelData AnalysisRaster modelData CollectionVector modelRelational and RulesObject model
- 3. nodeBnodeCPolygonIPolygonIIInodeAPolygonIInodeEnodeFnodeDPolygonVPolygonIVnodeGCoding Vector GISYou’ve seen this before.Let’s break it down.Vector Mode Model of RealityReality
- 5. nodeBnodeCPolygonIPolygonIIInodeAPolygonIInodeEnodeFnodeDA topologic vector model records the points and linesshared between polygons as unique items, thus every oneof the points and lines are recorded in the data only once.
- 6. nodeBnodeCnodeAPolygonIInodeEnodeDPolygon 2 is on the right sideof the line ABCED.
- 7. PolygonIPolygonIIInodeAPolygonIInodeEnodeFnodeDPolygonVPolygonIVPolygon 2 knows it’s adjacentto Polygons 1, 3, & 4.It shares a line segment with each. Polygon 2 knows it touchesPolygon 5.It shares node E with Polygon 5.
- 8. nodeBnodeCPolygonIPolygonIIInodeAPolygonIInodeEnodeFnodeDPolygonVPolygonIVnodeGStrict TopologyFeatures are composed from a common set of points and lines.Altering the vertices of one polygon affects polygons that share those vertices. Harder to introduce gaps or slivers.
- 9. ObjectsGIS Features as Objects is a recent method of representing aspects of the real-world in GISExample of the shift from specialty data to DBMS that are spatially-awareNon-planar, temporally shifting, topologically linked, rule-based actionsStill important to check for topology to ensure as a quality control step
- 10. Vector Geometry as ObjectsParcelsPlanar geometries with attribute informationParcels 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)
- 12. Attributes as ObjectsNot 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 actionsOwnership record linked to GIS parcelSearch on multiple owners, recordsRemoval of parcel warns about “orphan” ownerFunctions that can be performed by GIS analyst can be embedded in the actual database
- 13. Manipulating Vector Mode Databases
- 14. Common OperationsSelection by Attributes or LocationDissolveAppendClipIntersectUnion
- 15. Select by AttributesCreate 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
- 16. Select by LocationProximity or overlay based on features in one layer and features in another layer or the same layer.Several methods to compare proximity & overlayDistance fromTouching (on edge)Contains or WithinPartial OverlapsExact Matches
- 17. Dissolve
- 19. Append
- 20. Layers to Append Input Layer 1Input Layer 2Appended LayersOverlapping Polygons/Polylines are preserved!
- 21. Clip
- 22. Input Layer & Clipping LayerClip PolygonInput LayerClipped FeaturesOutput Layer
- 23. Intersect
- 24. IntersectionWhere are the Road segments that are in flood prone areas.Select flood prone from Input Layer 1Intersect roads and flood prone [Layer 2].
- 25. Input Layer 2RoadsIntersect FeaturesInput Layer 1StreamFloodProneNo FloodPanel 1
- 26. Intersect FeaturesInput Layer 1StreamFloodProneQuestion: where are the road segments that pass through flood prone areas?No FloodInput Layer 2RoadsPanel 1
- 27. Intersect FeaturesInput Layer 1StreamFloodProneNo FloodSelect flood prone areas and then intersect Input Layer 1 with Layer 2 Roads.Input Layer 2RoadsPanel 2
- 28. Intersect FeaturesOutput Layer RoadsFloodProneStudy AreaRoads that pass through flood prone areas. Attributes of both layers maintained in table.Length of roads in flood areas becomes attributePanel 3
- 29. IntersectionWhere are the places that are residential and flood prone?Select flood prone from Input Layer 1Select residential from Input Layer 2Intersect
- 30. Intersect FeaturesInput Layer 1StreamFloodProneNo FloodPanel 1
- 31. Intersect FeaturesInput Layer 2ResidentialCommercialIndustryPanel 2Open space
- 32. Intersect FeaturesInput Layer 1StreamFloodProneNo FloodInput Layer 2ResidentialCommercialIndustryPanel 3Open space
- 33. Intersect FeaturesOutput LayerResidential &Flood ProneExtentPanel 4
- 34. Panel 2Panel 1Panel 3Panel 4
- 35. Union
- 36. Panel 1Agricultural Land UseCornGreen BeansTomatoesWheat
- 38. Panel 3Agricultural Land UseCornGreen Beans & PoorCorn &PoorGreen BeansTomatoesCorn & ExcellentGreen Beans & FairWheatTomatoes & FairWheat & ExcellentSoil QualityPoorWheat & GoodFairTomatoes & GoodGoodExcellent
- 39. Let’s See How It Works
- 40. Dissolve
- 41. 1. Right Click2. Click to select.Dissolve Operation
- 42. 2. Click to open Add Field dialog1. Click to open menuAddFieldforDissolve
- 43. Type a name and click OKNameandTypeofFieldforDissolve
- 44. Table with Code FieldResultingfield
- 47. Dissolve
- 49. 1234AppendDialog
- 50. AppendTwo layers before appendOne layer after append
- 52. 123ClipDialog
- 53. ClippingRoads before clippingRoads after Clipping
- 54. Intersection
- 55. Intersection ProcedureWhere are the areas that are residential in land use and flood prone?Select flood prone areas from flood prone layerSelect residential areas from land use layerDo intersection
- 56. Intersect
- 57. Residential
- 58. SelectbyAttributesDialogSelecting flood prone and water areas
- 64. 123456IntersectionDialogRemember, if you did a selection, then get input features from drop down or drag into dialog from TOC
- 67. Union
- 69. 12345UnionDialog
- 70. This map depicts land use patterns for a portion of Washington Township prior to performing the union operation in which land use and flood prone layers were overlain.This map depicts land use patterns for a portion of Washington Township after performing the union operation in which land use and flood prone layers were overlain. Notice that some of the land use polygons have been cut creating new polygons. This occurs in areas in which a polygon from the flood prone layer intersects a land use polygon. The attributes of the new layer enable the analyst to map the coincidence of each land use category with each flood proneness category.