Week 1 Flashcards
(27 cards)
what is spatial data
contains positional information such as latitude or longitude
what is geospatial data
spatial data that has been georeferenced (to some projection)
what is geoinformation
interpretation or analysis outcome of spatial/geospatial data
what is metadata
data about the data
its requirements are defined by the UK Geospatial Commission
what is geopackage
a storage system that can handle many layers in a single file
what are database management systems
- for large and complex GIS projects, a geodatabase system is important
- database management systems (like DB manager) allow you to set up, use and maintain a database
- maintains data backup and recovery functions - key aspects for big data
- query and link
what is a raster
- a matrix of square areas that define a single georeference
- efficient for large data
- comprised of pixels
what are discrete and continuous rasters used for
discrete - categorical
continuous - elevation
advantages and disadvantages of a raster
adv:
- simple data structure
- simple application for overlays
disadv:
- less compact data structure (big file size)
- poor representation of topology
- cell size vs feature boundary
what is a vector
- uses isolines of the field to define points, lines and area (polygons)
- lines and vertices
what are points, polylines and polygons vectors used for
points - xy coordinate e.g. outcrop, intersection
lines - connect points e.g. roadways, rivers
polygons - connected lines e.g. country, lake
advantages and disadvantages of vectors
adv:
- efficient representation of topography
- scalable
- simple network analysis
- easily connected to attribute data
disadv:
- complex data structures
- overlay function is difficult
vector vs raster
-vector more spatially accurate
-raster better for variable changes
what is topology
spatial relationships between neighbouring features
common raster files
- ASCII Grid (*.asc) - tiled raster datasets
- remote sensing data: commonly rasters. HDF, BIL, etc.
-GeoTIFF (or TIFF) - compressed tiled color (or black/white) scale format - common for topography (DEM) data
common vector files
- shapefiles (*.shp) - most common! multiple-file database that includes metadata
- KMZ: used in Google Earth and GIS
- represent features using points, lines (and vertices) and polygons
why is there uncertainty in data quality
- positional accuracy - measurement accuracy. function of scale data was mapped
- quantitative accuracy of attributes
- conceptual accuracy: grouping/clustering
- mapping accuracy: datum and projections
- human error
what can be done with the data collected/organised
- classify/measure
- overlay
- neighborhood functions - buffer, interpolate, topographic functions
- connectivity (network analysis)
describe classification
- merging data (polygon or raster) based on user input
- fitting based on defined interval from attributes
describe overlay
- one of the most common applications. used to understand the spatial relationships
describe neighborhood functions
- buffer creates polygons around defined features given some distance
- can be used for both vectors (points, lines polygons) and raster
what is inverse distance weighted (IDW)
see powerpoint 1 slide 20
describe interpolation
interpolate: translate point-scale data across a region i.e. creating continuous surface from discrete data points
kriging: spatial interpolation method that takes into account correlation space
describe topographic functions
- terrain analysis using elevation models:
- slope
- aspect
- flowlines (akin to delineating surface water flows)
- hydrology toolboxes: for watershed delineation
