topic Re: Subdividing parcels in ArcGIS CityEngine Questions

Subdividing parcels

MattO_Keeffe1 — Thu, 01 May 2014 20:08:23 GMT

We own large plots of land and I'd like to calculate optimum plot sizes and locations for a subdivision. I seem to recall a presentation or a video where CityEngine was doing just that and was hoping that someone might be able to advise.

As an example, we have an irregular shaped, five acre plot of land which fronts onto the water. We want to subdivide this land into plots so that individuals can build their own house on the plot.

We'd like to be able to throw a number of parameters into (hopefully) CityEngine which would then optimise the use of the land to get the best possible outcome. For example:

Each plot should be > 0.3 acres but < 0.5 acres

Each plot should be at least 100 feet wide and 100 feet long

A plot can be an irregular shape if necessary

A canal which is at least 50 feet wide should be built into the original parcel to give every plot at least 30 feet of water frontage

An access road should be built into the original land so that every parcel is connected to the road network

I'm not sure if CityEngine is designed to do this sort of thing. Can anyone help?

Re: Subdividing parcels

MatthiasBuehler1 — Fri, 02 May 2014 10:26:09 GMT

Hi,

Well, this is a 'design problem' .. There's no software in this world that does 'good design' for you.

Imagine the problem of placing 1 building on 1 square parcel. There's literally an infinite variation of results possible. Can any computer solve this problem well ? No. Especially not, since urban design's an n-dimensional problem.

CityEngine provides the tools that help you design faster, reduce the iteration times considerably, but it's not a blackbox that spits out a well-designed masterplan. 🙂

CityEngine is a 'procedural modeling application', so it's really fast at producing 3d models based in input shapes and attribution. What you ask is basically to wind up with the parcel / footprint shapes in the first place, which is the actual design process. Of course, you can write CGA code that produces such shapes / distributions, but the 'semantics of the design' you reach for must be encoded in CGA.

==> 'Some' things are faster/more efficiently designed by hand instead of writing the rules. It's all about balancing things..

(Sure, you can do these things in CE, I just want to state this honestly.)

Does this make the situation a bit clearer ?

Matt

Re: Subdividing parcels

MattO_Keeffe1 — Fri, 02 May 2014 12:36:58 GMT

Perhaps I should have been clearer.

We're not intending to use something like this to create a well-designed master-plan. We'd like to use it to see what the potential plot inventory might look like on a piece of land. Occasionally we get asked to 'mock-up' something like this manually. The parcel of land might be huge. It takes time and there's always a suspicion that, if some sort of mathematics and topological rules had been applied, we could have squeezed a few more plots into the parcel.

As I mentioned in the original post, I'm sure I've seen a demonstration of something like this in CE where parcels/roads etc get redrawn on the fly as the route of a road is moved around because of the CGA rule which applies to the objects.

What we need is simply a tool which enables us to estimate the potential of a site but in a bit more of an intelligent way than us drawing it manually.

To use your building/parcel analogy, there are infinite ways of putting a building on a parcel until you tell CE that you want the centroid of the building to be in the same position as the centroid of the parcel. If I can apply a rule to that, hopefully I can apply the other rules mentioned in the original post. I just wouldn't know where to start (or if it's even possible).