gis kriging
DESCRIPTION
Short presentation on what is kriging and how to use it in ArcGIS.TRANSCRIPT
KRIGING By Bryan
WHAT IS KRIGING?an advanced geostatistical interpolation tool that generates an estimated surface from a scattered set of points with z-values based on statistical models that include autocorrelation, the statistical relationships among the measured pointsinteractive investigation of the spatial behavior of the phenomenon represented by the z-values should be done before selecting the best estimation method for generating the output surfacegeostatistical techniques not only have the capability of producing a prediction surface but also provide some measure of the certainty or accuracy of the predictions
HOW KRIGING WORKS…Kriging assumes that there is a spatial correlation within the distance and direction of each sample points and this correlation can be used to explain variation in the surfaceThe Kriging tool fits a mathematical function to a specified number of points to determine the output value for each location Kriging is a multistep process and includes exploratory statistical analysis of the data, variogram modeling, creating the surface, and exploring a variance surface. Kriging is most useful when there is a spatially correlated distance or directional bias in the data is known
LET’S BEGIN…Add the Boston and Superfund_Sites shapefile to a blank ArcGIS map and make the Boston shapefile hollowGo to Toolbox Spatial Analyst Tools Interpolation KrigingOrdinary semivariogram: Spherical
PARAMETERSInput Point Features: the input point features containing the z-values to be interpolated into a surface rasterZ value field: the field that holds a height or magnitude value for each point (this can be a numeric field or the Shape field if the input point features contain z-values)Output Surface Raster: the output interpolated surface raster and is always a floating-point rasterSemivariogram properties: 2 models (ordinary and universal)Universal kriging types assume that there is a structural component present and that the local trend varies from one location to another
Ordinary semivariogram have 5 models: Spherical, Circular, Exponential, Gaussian and Linear
Universal semivariogram have 2 models: Liniear Drift and Quadratic DriftI did not work on Cell Size and Search Radius since they were optional
MORE EXAMPLESOrdinary semivariogram: Circular
ALL OTHER ORDINARY SEMIVARIOGRAMS
Exponential Gaussian Linear
UNIVERSAL SEMIVARIOGRAM: LINEAR
UNIVERSAL SEMIVARIOGRAM: QUADRATIC
ORDINARY SEMIVARIOGRAM AT NUMBER OF POINTS = 30
Spherical 30 points
Spherical 12 points
UNIVERSAL SEMIVARIOGRAM AT NUMBER OF POINTS = 30
Linear at 12 points Linear at 30 points