forsys-sp / patchmax

A spatial selection optimization algorithm in ForSysR
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Area weighted vs not area weighted objective function #22

Open michelledayusfs opened 1 year ago

michelledayusfs commented 1 year ago

This is issue is just to document the reason we do not want patchmax to convert an objective to an area weighted objective.

  1. The original objective may already be area weighted (e.g., timber volume per acre); how would patchmax know it was already area weighted? For example, if I prioritize probability of flame length > 8ft, and patchmax automatically area adjusted it, it will take a large stand with a large probability, and turn it into a small number. Likewise, a small stand with the same large probability, will have a high value. If I am trying to hit my treatment constraint, I'd rather choose the large stand with the large probability, than a small stand with a large probability. If that small stand isn't completely surrounded with other stands of high probability I may get a suboptimal solution.
  2. This is how ForSysX works. It does nothing "behind the scenes". If your objective or priority is a total, like timber volume, you check a box to tell it, then it will divide by the area.

If we hind things from users you have no idea what patchmax is doing, and we need to allow greater flexibility. You can't undo the patchmax autocalculate, but you can manually create an area adjusted objective.

SOLUTION: Do not area adjust objective behind the scenes in patchmax. Cody will implement this solution.

FROM PEDRO:

"In the old version of Patchmax: We should never use total objective contribution values! It doesn’t make sense in the code. The algorithm will multiply the vectors “Objective per acre x Area in acres” coupled with area constraint, to produce the individual Project contribution. And will compare all projects from the seeds. There isn’t other way to do this. The objective vector is not used “alone” to prioritize anything in any case."