DTM, DEM, Interpolation, and TIN Flashcards
Define surface data
Spatially continuous data that includes distribution of temp, rainfall, or pollution
What are the four representing surfaces?
points, contour lines, surface rasters, and TINs
Surfaces: Explain points
z values that represent elevation, temp or rainfall
Surfaces: explain contour lines
- isolines of constant elevation with a specified interval - does not represent anomalies
Surfaces: explain surface rasters
models built from sample points on the surface
Define extrapolation
an estimation of a value based on extending a known sequence of values beyond the known area
Define interpolation
estimation of a value within two or more know values in a sequence of values
What is waldo tobler’s first law of geography?
“everything in space is related, but near things are more related than far things”
Explain global interpolation
- use all available data to create a surface
- used when there is an underlying structure to the entire dataset
- used when a global trend needs to be determined
Explain local interpolation
using data in a limited area
Explain exact interpolation
- surfaces pass through every point in the dataset
- used when there is a high degree of uncertainty attached to the measurements made at the observed data points
Explain stochastic interpolation
- points that were observed to produce known data points
- methods of randomness
Explain restricted interpolation
- interpolation that does not go beyond max and min sample points
- used when sample includes critical points
Explain proximal interpolation
- polygons are determined by the configuration of the data points
- can also be called nearest neighbor classification
- used with qualitative data
- ex: thiessen polygons
Explain inverse distance weighting (IDW)
assumes that each input point has a local influence that diminishes with distance - weights the points closer to the cell than those far away
