In a previous post, I described how to create a hybrid hillshade from a standard bare-earth DEM and a DEM including canopy. Well, what if you don’t have a fancy canopy DEM? Do you have classified LiDAR data, or know where to get your hands on some? Then you are in luck! I’m here to walk you through the process of creating your very own canopy DEM in ArcGIS.
A popular cartographic element is the venerable hillshade. With a good hillshade and a transparent overlay, you can add a lot of topographic context to your map without being overly distracting. Most of us have probably used a bare earth hillshade before. These are great if you just want to look at the underlying terrain, or if you are covering a wide area.
For close-in work, creating a hillshade from DEM that includes the vegetation canopy can make things much more interesting. However, if you look closely at the canopy hillshade, you’ll notice that many of the terrain features no longer stand out, even where there is little to no vegetation. This is because individual trees and shrubs create more steep areas, which proceed to hog the dark end of the stretched histogram. So what’s a cartographer to do? Continue reading “Taking the Best of Both Worlds for a Better Hillshade”
In flow accumulation modeling, a common bit of data needed is the average upslope value of a parameter of interest, such as slope or curvature. In most cases, this is simply a matter of calculating a flow accumulation weighted by the parameter in question, then dividing this by the unweighted flow accumulation. But what if you want average upslope aspect? Since aspect is measured in degrees, and a value of 0° and 360° are the same, a simple arithmetic mean will be useless. So, what to do? In this post, I will walk you through the process of calculating the mean upslope aspect using ArcGIS, and leave you with a working python script that will automate the process.
This week, I’ve taken MAPCITE’s Excel plugin for a quick test drive to see what it can do. I’m not getting any money, endorsements, or other compensation for this, so these are my own thoughts on the product. The software is easy to install and easy to use, and provides valuable added functionality to Excel. There were some limitations and a few stumbling blocks, but overall this is a useful product. Read on for the full report.