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GEOM2001 L5-8

Why use data bases Mapping products Workflow to assess and manage activities Provide support for businesses and become integrated with everyday activities
Queries select rows in database tables based upon a logical expression and returns results as correct or incorrect
Relational tables are required to have No repeating or redundant data Represent a valid state of the world Maintain a valid state representation of modelling application Unique data in each row
Attribute join creates a table view (for display and queries) as the combination of 2 tables based upon matching values between fields
Cardinality relationship between parcel and owner one-one - one parcel has 1 owner one-many - 1 parcel has many owners or many parcels has 1 owner many-many - many parcels have many owners
Advantages of raster analysis oAbility to analyse continuous surface variable eg slopes, density etc oFlexibility to perform other spatial analysis on proximity, hydrological models, filtering local trends etc i.e. hot spots, travel time to destination
Local operations operating on each cell value in layer(s)
Neighbourhood operations defined by focal cell and surrounding cells
Zonal operations on groups of cells identified by zone
Global operation incremental operations on entire raster ie distance, flow descent
Cost distance movement through the cell can have friction
Aggregation (merging) simplify and summarise data to reveal overall trend
Disaggregation (splitting) divide data to analyse data relationships
'Dissolve' feature Output merged by geometry - groups by shape
Spatial join query to relate features based on spatial relationships
Union tool builds new feature class by combining features and attributes of input feature classes
Update tool updates the attributes and geometry of an input feature class or layer by the update feature class or layer they overlap
Intersect tool builds new feature class from the intersecting features common in both feature classes
Clip tool builds new feature class from input features overlying the clip feature i.e. as a cookie cutter
Ecological fallacy Errors due to performing analyses on aggregate data when trying to reach conclusions on individual units
Solutions to ecological fallacy minimise spatial variation in data Dasymetric mapping - uses correlated data to statistically relate disaggregate data
Sliver polygons occurs as small slivers along versions of similar boundaries causing overshooting/undershooting on intersections when digitising features
Solutions for sliver polygons Use a fuzzy tolerance to make boundaries common Eliminate tool merges slivers
Terrain analysis Deals with properties of topography/terrain
Digital elevation model Is a raster model which refers to any digital rep of a topographic surface
Triangulated Irregular Network A vector data model to represent the land surface with a series of non-overlapping triangles
Benefits and disadvantages of DEM + Faster processing and more efficient - Less flexible, can't update/add new data
Benefits and disadvantages of TIN + Flexible with input data - Less widely available than raster surface models
Slope Change in elevation (a rise) with a change in horizontal position (a run) at a surface location
Aspect compass direction that the sloping surface faces at each location
Vertical profile Shows change in elevation along a line
3D draping Superimpose data such as satellite imagery, hydro features, land cover, vegetation, roads etc on the perspective view to make it more realistic
Viewshed the portion of the land surface that is visible from one or more viewpoints
Watershed the upslope area contributing flow to a given location
Created by: cmw001001