Developer Notes
The manual digitization of vector datasets for use in ScrollStats results in a significant amount of work for users before they can start generating data. Automated ridge line creation has been attempted to ease this burden, however, the resulting lines proved to be a significant impediment for the migration pathway algorithm to reach the back of the floodplain and the process by which they were generated is incapable of intelligently connecting ridge areas split by cross-cutting drainage.
Automated ridge creation was attempted by using functions like skeletonize or medial_axis on the ridge area raster created by ScrollStats. These skeletonization functions resulted in high-detail line features for each ridge area identified in the ridge area raster often with smaller spurs attached near the end of the ridge.
Spurs generated from skeltonization (red) of a ridge area (white)
These spurs drastically diverted the trajectory of the migration pathway algorithm causing the transects to prematurely halt, self-intersect, or turn around completely.
Pruning of the spurs did significantly improve the performance of the migration pathway algorithm, however we still found that the resulting transects would veer off-course and/or fail to reach much depth into the floodplain relative to the manually created ridge lines.
Transects generated using skeletonized ridges fail to reach the back of the floodplain
However, even if the spurs were not an issue, this method also faces a significant limitation in that it cannot connect ridge areas that were once connected but have since been split by cross-cutting drainage.
Auto delineated areas (purple) broken up by cross-cutting drainage
While it has yet to be determined if maintaining these connections between separated ridge areas is the "correct" way to go about this, any method of generating a ridge line for each ridge area will have this fundamental limitation
Because of these issues with the spurs and the inability to connect ridges separated after their deposition, we decided to move forward with recommending manual ridge line creation for now and continue to work on developing new methods for creating ridge lines.