Inverse Distance Weighting and Kriging in R

I posted a few months ago about a new R package I wrote with Filipe Matias-- it's available for download on GitHub. Last week we extended the GitHub tutorial to include interpolation methods and raster visualization/mapping example code. Spatially Challenged readers have asked me to write tutorials on these techniques before, but I had been… Continue reading Inverse Distance Weighting and Kriging in R

Geographically Weighted Regression in SAGA

Since I mentioned kernels last week, I figured this would be a good time to go over the geographically weighted regression (GWR) procedure in SAGA. Once again, I don't have good example data I can post online for this topic, so you'll have to forgive the lack of pictures. GWR is an interesting method with… Continue reading Geographically Weighted Regression in SAGA

Types of Curvature

Curvature, the second derivative of elevation, is a very useful terrain derivative. It describes how convex or concave a surface is, which helps predict soil moisture (among other things). The basic terrain analysis feature in SAGA calculates plan curvature and profile curvature. Profile curvature goes with the direction of maximum slope, which helps estimate acceleration… Continue reading Types of Curvature

Defining Common Terrain Derivatives

Last month I shared some ways to calculate terrain derivatives in SAGA, focusing on the Basic Terrain Analysis function. Today I'm going to give you a quick overview of what each derivative means and some of its potential uses. Let's start with the most intuitive ones. Slope is how fast elevation is changing. A higher… Continue reading Defining Common Terrain Derivatives