For the geoscientists in the audience who are using my upslope area functions, I just updated the files. The update fixes a problem with the computation of influence and dependence maps for data... read more >>

Back in March I started writing about an algorithm implementation experiment for computing upslope area. Given an "image" whose pixel values are terrain elevations, the upslope area of a pixel is... read more >>

Since I originally posted my upslope toolbox to MATLAB Central back in August, I have heard from some experts about an issue related to NaNs in the DEM data. Specifically, some data sets... read more >>

At the beginning of the upslope area series, I posted code showing how to compute the direction of maximum slope for a triangular facet, and how to compute the flow direction for a pixel. This... read more >>

In my August 7th post on upslope area, I showed how to construct and solve the flow matrix to determine the upslope area for every pixel in a digital elevation model (DEM). In addition,... read more >>

Earlier in this series I have discussed the problem of plateaus. Specifically, how do you assign a flow direction to a DEM pixel that has no downhill neighbors? I proposed in part 5 that the... read more >>

About twelve years ago, I was implementing the algorithm that became roifill in the Image Processing Toolbox. In this algorithm, a specified set of pixels is replaced (or filled in) such that... read more >>

After my last upslope area post, I decided that I had enough of the algorithm details worked out to produce a set of working M-files. Although I have a few more posts to go, I've already uploaded... read more >>

So far in this series I've talked about calculating pixel flow directions and handling plateaus, but I haven't yet discussed the actual upslope area calculation. The Tarboton paper... read more >>

In part 4 of this series I classified DEM plateaus into: ... read more >>