[postgis-users] Cut off 1-acre of a parcel

[Greg Troxel]

  Now I'm ready to tackle one of my larger problems.  I'm working with a
  cadastral layer and forecasting future development patterns.  I have a
  need to simulate subdivision, where a large vacant parcel (say, 640
  acres) will realistically be developed in the future in smaller chunks
  (say, 1 acre).  Right now I ignore the spatial part of it, and end up

I realize that I'm not helping with your specified problem formulation,
but that breakup scheme doesn't sound realistic.  Besides acreage,
there's frontage, and that will typically result in street as well being
laid out.  I'm sure you realize this and that you're trying to get a
rough estimate for some other planning purposes.

So, I'd generate a formula that takes a size and estimates the number of
lots that can be created, and that might be dividing 80% of the space by
the lot size or something, perhaps based on some recent actual
subdivision plans with your zoning rules.  Then, I'd write some code
that takes a large parcel and fully breaks it up into that number of
lots (ignoring the street layout issue), and store that infromation, and
then construct the residual large parcel based on unioning the lots that
aren't yet carved out.  The difference in approach is that you'd perhaps
divide the parcel into 10x12 chunks rather than taking 1 acre off at a
time and getting bizarre residual shapes.  Perhaps bizarre residual
shapes are appropriate, and you can model the developer holding on to
them for 20 years and finally some abutter buying them....