school of geography faculty of environment point-surface interpolation
TRANSCRIPT
School of GeographyFACULTY OF ENVIRONMENT
Point-surface interpolation
Day 1: point-surface interpolation
• Principles
• Tobler’s First Law of Geography and spatial interpolation
• Classification of methods
• Common methods
• Thiessen polygons
• Trend surfaces
• Inverse distance weighting (IDW)
• TINs
• Geostatistical Analyst in ArcMap
Principles of interpolation
• Tobler’s First Law of Geography
• “Everything is related to everything else, but near things are more related than distant things.”1
• Spatial interpolation
• The procedure of estimating the values of properties at unsampled sites within an area covered by existing observations
• important in addressing problem of data availability
• quick fix for partial data coverage
• interpolation of point data to raster surface
• role of filling in the gaps between observations
1W. R. Tobler, (1970) "A computer movie simulating urban growth in the Detroit region". Economic Geography, 46(2): 234-240.
Classification of methods
• Methods of spatial interpolation:
• many different methods available
• e.g. Thiessen polygons
• e.g. Inverse distance weighting
• classification according to:
• exact or approximate
• deterministic or stochastic
• local or global
• gradual or abrupt
• Remember! Tobler’s First Law of Geography
Common methods
• Thiessen polygons
• Gradual or abrupt?
• Exact or approximate?
• Local or global?
• Deterministic or stochastic?
Common methods
• Trend surfaces
• Gradual or abrupt?
• Exact or approximate?
• Local or global?
• Deterministic or stochastic?
Common methods
Common methods
• Inverse Distance Weighting (IDW)
• Gradual or abrupt?
• Exact or approximate?
• Local or global?
• Deterministic or stochastic?
Common methods
• Triangulated Irregular Networks (TINs)
• Gradual or abrupt?
• Exact or approximate?
• Local or global?
• Deterministic or stochastic?
Geostatistical analyst
• Geostatistical analyst in ArcMap
Practical exercise
Hands-on Exercise #2Interpolating point data in ArcGIS