search

natcap / invest

InVEST®: models that map and value the goods and services from nature that sustain and fulfill human life.
Apache License 2.0
166 stars 68 forks source link

LS Factor: restore the weighted mean of proportional flow #1413

Open phargogh opened 1 year ago

phargogh commented 1 year ago

In our recent LS Factor update (ADR here: https://github.com/natcap/invest/blob/main/doc/decision-records/ADR-0001-Update-SDR-LS-Factor.md), we removed the weighted mean of proportional flow, replacing it with the dot-product sin(alpha) + cos(alpha) to represent the flow length across a pixel.

In revisiting Desmet & Govers (1996), it turns out that they actually use both of these methods in the calculation of the LS Factor (and they even use an MFD algorithm) ... but I probably took out the weighted mean part because SAGA doesn't do it because they're assuming D8 flow.

In any case, look back into D&G(1996) and make sure we're doing the right LS Factor calculations, see how much this changes things, run the new build by Rafa and be sure to note the new change in an ADR, HISTORY and the User's Guide.

phargogh commented 1 year ago

FYI @schmittrjp

schmittrjp commented 1 year ago

Thanks - keep me posted on this @phargogh

dcdenu4 commented 1 month ago

Hey @phargogh, just checking in on this issue and status and where we might want to place it for a Milestone.

phargogh commented 1 month ago

No progress has been made yet except for this issue. I've removed the in progress tag for now until I (or someone else) can get to it.