Creation of time-of-flight shade masks for NEON AOP

This set of code generates shade masks for NEON AOP data by combining sensor and solar view angles with surface models through a ray tracing algorithm. Shade masks can be generated either based on the digital surface model or from the digital terrain model combined with the canopy height model. This code was created as part of an effort to generate foliar trait maps throughout the Department of Energy (DOE) Watershed Function Scientific Focus Area (WF-SFA) site in Crested Butte, CO in association with NEON's Assignable Asset program.

A full description of the effort can be found at:

K. Dana Chadwick, Philip Brodrick, Kathleen Grant, Tristan Goulden, Amanda Henderson, Nicola Falco, Haruko Wainwright, Kenneth H. Williams, Markus Bill, Ian Breckheimer, Eoin L. Brodie, Heidi Steltzer, C. F. Rick Williams, Benjamin Blonder, Jiancong Chen, Baptiste Dafflon, Joan Damerow, Matt Hancher, Aizah Khurram, Jack Lamb, Corey Lawrence, Maeve McCormick. John Musinsky, Samuel Pierce, Alexander Polussa, Maceo Hastings Porro, Andea Scott, Hans Wu Singh, Patrick O. Sorensen, Charuleka Varadharajan, Bizuayehu Whitney, Katharine Maher. Integrating airborne remote sensing and field campaigns for ecology and Earth system science. Methods in Ecology and Evolution, 2020.

and use of this code should cite that manuscript.

Visualization code in GEE for all products in this project can be found here:

https://code.earthengine.google.com/?scriptPath=users%2Fpgbrodrick%2Feast_river%3Aneon_aop_collection_visuals

Shade masks for this project are available as assets on GEE:

DSM Shade: https://code.earthengine.google.com/?asset=users/pgbrodrick/SFA/collections/shade_priority.
DTM + CHM Shade: https://code.earthengine.google.com/?asset=users/pgbrodrick/SFA/collections/shade_tch_priority.
and are included in the following data package:

Brodrick P ; Goulden T ; Chadwick K D (2020): Custom NEON AOP reflectance mosaics and maps of shade masks, canopy water content. Watershed Function SFA. DOI: 10.15485/1618131

Additional relevant repositories:

Atmospheric correction wrapper:

https://github.com/pgbrodrick/acorn_atmospheric_correction

Shade ray tracing:

https://github.com/pgbrodrick/shade-ray-trace

Conifer Modeling:

https://github.com/pgbrodrick/conifer_modeling

Trait Model Generation:

https://github.com/kdchadwick/east_river_trait_modeling

PLSR Ensembling:

https://github.com/pgbrodrick/ensemblePLSR