Wednesday, June 28, 2017

New Job!!!

This summer I'll be transitioning away from Dartmouth to a tenure-track position in the Geography Department at the University of Northern Iowa.

I've updated my contact info on my About Me page.

Tuesday, October 4, 2016

New Articles

Here are two recent articles that I was working on over the summer, both in Earth Surface Processes and Landforms. Enjoy!

Dietrich, J. T. (2016) Bathymetric Structure from Motion: Extracting shallow stream bathymetry from multi-view stereo photogrammetry. Earth Surface Processes and Landforms, doi: 10.1002/esp.4060.
http://onlinelibrary.wiley.com/doi/10.1002/esp.4060/abstract

Carbonneau, P. E., and Dietrich, J. T. (2016) Cost-effective non-metric photogrammetry from consumer-grade sUAS: implications for direct georeferencing of structure from motion photogrammetry. Earth Surface Processes and Landforms, doi: 10.1002/esp.4012.
http://onlinelibrary.wiley.com/wol1/doi/10.1002/esp.4012/abstract


Friday, August 26, 2016

New Off Nadir Resolution Calculator

A quick update, I uploaded a new Python off-nadir resolution calculator to my GitHub:

https://github.com/geojames/py_offNadir_Res

It only works for low-oblique images (theoretically it would also work for nadir images if you set the pitch of the camera to zero). It calculates the pixel resolutions for the near field (closest to the camera), mid field (at the principal point), and the far field (furthest for the camera). It will also tell you the area that each image covers.

If your interested in how it works head over to the GitHub repository.

Tuesday, January 12, 2016

Amethyst Brook Dam Removal

Some footage from last week's dam removal on a stream that we (Dartmouth) have been doing extensive monitoring on in West-central Massachusetts (near Amherst).


More photos of the site post-removal are here: https://goo.gl/photos/xxTxe34HzTcnPozr8 (some are thanks to Alex Hackman of Mass. Fish and Game)

Friday, December 4, 2015

GIS Change Detection Math

I do a lot of topographic\geomorphic change detection, mostly with raster digital elevation models but I've also started getting into point cloud differencing too. It's simple subtraction, but the way you do your subtraction can make a big difference in how you interpret the data. I've had several students ask about this, so I thought a short write up was in order. The examples here are topographic (erosion and deposition), but the concepts apply to any raster-based change detection (i.e. land use/land cover change).