Trend Surfaces and Krigging

Do This:
A.

Load Spatial Analyst
Load trendsurf.ave (scripts, new, load from text file), compile it, change the name and add as a tool to your view (click, not apply).

Load soilsamp.shp
Run it! Choose extent same as soilsamp, accept the rest as defaults, click ok.
Choose a Z-value field (other than Ph)
Type 1 for the power of the surface.

Do it again with a power of 2 or 3

Examine the residuals:

Load 3D Analyst, Convert soilsamp to 3D a shapefile, add a field called trend, extract Z values using field_calculator, shape.getz, add a field called residual, subtract trend from your original data.

Choose Field->Statistics to get the Mean and Standard Deviation of your residuals field.

B.
Krigging:

Open ArcGis->Arcmap
Add soilsamp.shp
Turn on Spatial Analyst (tool, extensions…)
Right-click on the menu bar and choose Spatial Analyst
Choose Interpolate to Raster from the Spatial menu, and Choose Krigging
Choose your Z field, Choose Universal and accept the rest of the results.

That’s a Krig!!! Notice, if you have time, how it differs from the surface you created in Lab 4 of the same variable.

Turn in your krigged map (from part B), and your average and standard deviation of residuals on a 2nd order or higher surface (from part A).