GIS Terms and Concepts

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GIS Terms and Concepts
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Review

• Themes layers
• Types of themes
• point
• line
• polygon
• grid
• image

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Review

• Simple queries
• Used to highlight matching features
• Can be used to generate statistics
• Labels
• Label features using data
• Control over position, font, size, etc.
• Classification
• Method of displaying data graphically

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Point and Line Themes

• Point
• Ex. Wells
• Polygon centroids
• Line
• Ex. Roads, pipelines
• Has length

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Polygons and Grids

• Polygon
• An enclosed area
• Has area (acres)
• Grid
• a series of points on a uniform grid
• Used to create a surface or contour lines

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Images

• Ex. Aerial photos, scanned maps
• They are fitted to geographical space
• Cannot be attached to data
• Usually used as a back drop to vector data.

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Mapping Basics

• Projections
• ways to make a round wold into a flat map
• distance vs. area
• less important for small areas
• Map units
• decimal degrees
• other
• Scale Units
• feet, miles, km

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Mapping Precision

• Large scale maps generally lack precision to be
  useful for farm level GIS.
• More precise maps are made using surveying,
  aerial photos or Global Positioning Systems (GPS)
• Lack of precision can have substantial effects on
  spatial analysis (like acreage calculations)

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What is ArcView?

• A desktop GIS
• Allows the user to create, edit , view and
  analyze spatial data.

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ArcView

• Basic Functions
• Views (like ArcExplorer)
• Layouts
• Tables (data)

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Views

• Similar to ArcExplorer
• Can be used to edit vector data.
• Themes can be created from coordinate data (event
  themes)
• Classification has more power than ArcExplorer
• Themes are attached to one or more tables
• Complex queries and spatial joins are possible

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Tables

• Contain the data component
• Use standard dbase (dbf) files.
• Tables can be accessed by Access or Excel
• Allows common database operations like joins or
  links
• Delimited text can be imported.

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Layout

• The map creation tool.
• Add text, views, scale, etc.
• Can be live linked to a view.
• Can be used to combine several views.