This Directory contains two packages (sfm_precision and sfm_gridz). A more detailed readme is provided in the subfolders. The code for our in-review paper "Using aerial photogrammetry to detect significant canopy height change resulting from beaver foraging" is given in GRAHAM_ET_AL_2021_PROCESSING/Analysis folders.

Scope of Project/Packages
This project supports the calculation of precision maps to quantify uncertainty in structure-from-motion photogrammetric reconstructions, and the propagation of these uncertainties to robustly inform change detection analyses (after James et al., 2017). The method is a robust, raster based approach which allows for the propogation of both SfM precision and rasterisation uncertainty (aka. roughness)

sfm_precision
Package to be used with Agisoft Metashape (> 1.6). Methods used align with James, et al. (2017)

sfm_gridz
Create Digital Surface Models (DSM), SFM Precision Raster, Height Change Maps (with consideration of Precision and Roughness to determine limit of detection(LOD))

GRAHAM_ET_AL_2021_PROCESSING The processing workflow for point cloud data for our in-review paper "Using aerial photogrammetry to detect significant canopy height change resulting from beaver foraging". Mainly uses the sfm_griz module to covert point clouds to rasters e.g. DSMs, CHMs. ALso includes plotting of maps for the publication. generates the dataframes required for
GRAHAM_ET_AL_2021_Analysis

GRAHAM_ET_AL_2021_Analysis The Data Analysis for our in-review paper "Using aerial photogrammetry to detect significant canopy height change resulting from beaver foraging". The workflow consists of an R project and contains the workflow we used to analyse the DEM of difference maps produced using The GRAHAM_ET_AL_2021_PROCESSING.

References James, M., Robson, S., and Smith M (2017) ‘3-D Uncertainty-Based Topographic Change Detection with
Structure-from-Motion Photogrammetry: Precision Maps for Ground Control and Directly Georeferenced Surveys’.
Earth Surface Processes and Landforms 42(12):1769–88. https://doi.org/10.1002/esp.4125).