Fichas
Vector Data Analysis
Fichas del conjunto (33)
- 1Spatial analysisApplications of operations to turn raw spatial data into useful information
- 2Goals of spatial analysisReveals patterns, trends and anomalies that might otherwise be missed
- 3Components of spatial analysisSpatial data + operations
Input --> operation --> output
(usually chain of operations) - 4Spatial analysis: 3 spatial scopesLocal
Neighborhood
Global - 5Local scopeoutput depends solely on input at the location
ex: population density - 6Neighborhood scopeOutput depends on input at location and from nearby locations
ex: # of adjacent states - 7Global scopeOutput depends on the entire input layer
ex: Rank by state by total population - 8Three types of spatial analysisQueries and Selections
Measurements
Transformations - 9Queries and SelectionsType of spatial analysis
Analyses are conducted on the selection, no changes in DB occur
Attribute-based or location-based - 10MeasurementsCharacteristics of individual features, or of relationships between features
ex: distance, length, area, shape - 11TransformationsCreates new attributes or objects based on simple rules.
May create new attribute info from existing attributes
Uses geometric construction or arithmetic calculation. - 12Format of a 'SELECT' statementSelect; From; Where
- 13Format of Boolean expression1. (this) AND (that)
2. (this) NOT (that)
3. (this) AND (that) OR (this other thing) AND NOT (that other thing) - 14Equation of measuring the distance between 2 points on a cartesian planePythagorean's theorem
sqrt ((x2-x1)^2 - (y2-y1)^2) - 15What is a great circle on a sphere?Distance on a sphere
Complicated to derive... spherical analysis is rare - 16How to find shortest routes on a sphere?Spherical distance
- 17Relationship between length of a true curve & its polyline representation? Which one is longer?True curve is longer
- 18For 3D objects, why the length of polylines and area of polygons can be substantially longer than those on a 3D surface?Measurements in GIS are often made on 2D projections of 3D objects
- 19How is shape measured (conceptually)?Shape measurement captures the degree of contortedness of areas, relative to the most compact circular shape. Comparing perimeter to the square root of area.
- 20What is the shape value of a circle?Normalized! Equals 1.
- 21Relationship between shape value and contortedness of areas?The more contorted the area, the higher the shape measure
- 22Transformation analysisCreating new attributes or objects based on simple rules
ex: classification - 23How do we determine if a point lies in a polygon?Draw a vertical line up (north) from point to infinity. Count number of times the line intersects polygon boundary.
Odd = point inside
Even = point outside - 24Buffer analysisCreating a new object consisting of areas within a user-defined distance of an existing object
Ex: to determine areas impacted by a proposed highway - 25Overlay analysisCombines spatial and attribute data from multiple spatial layers
- 26Why do different layers need a common coordinate system for overlay analysis?So that entities match up
- 27Where are new nodes that are created in overlay analysis?Over 2 map layers: first find all intersections between the boundary lines
- 28Building TopologyNeed to give attributes to the polygons you created in overlay analysis
- 29What inputs do we use for clip, intersect and union?Bounding layer and data layer
- 30ClipRetain all elements of data layer inside bounding layer. Attributes retained only for data layer.
- 31IntersectRetain all elements where both bounding and data layers contain data. Combine attributes from both bounding and data layers.
- 32UnionRetain all elements. Combine attributes from both layers when they intersect.
- 33Overlay dimensionalityCan combine layers at different dimensions.
Output maintains lowest input dimensionality (point + line = point).
Información
- Descripción
- Final Exam GIS Fichas sobre Vector Data Analysis, creado por Sarah Bird3292 el 09/12/2015.
- Creado por
- Sarah Bird3292
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