More follow-up from meeting of February 2, 2004.

This page is designed to give an idea of relative ease and complexity of doing modeling.  Alternate scenarios are suggested to give an idea of ease of model implementation.  The reason for showing relative ease of implementation is to give the Taskforce some idea of what to expect in terms of timing of output.

1.  Easiest.
Suppose you wish to designate various targets of opportunity--say from among the premium parcels found in the analysis on the previous page--those parcels in the DDA that are already zoned to support premiums and that also do not lie in the floodplain or the historic districts.  If you also wish to restrict height on parcels within some distance of the historic districts, for example, this calculation is easy to make.  The two dimensional result is shown below, using a distance of 50 feet (with some rationale attached, such as sum of two street widths of 26 and 24 feet, or whatever).

• The animation shows first all premium parcels from before in orange;
• Then, premium parcels from the first frame within 50 feet of an historic district, in blue--if, for example, one viewed them as targets of opportunity for a 300 FAR (even though not all buildings in the historic districts are "short")
• The, premium parcels from the first frame more than 50 feet from an historic district, in red--if, for example, one viewed them as targets of opportunity for 600 by right with encouragement for parcel amalgamation
• The last frame shows both the blue and the red together so that one might get an idea of how the general pattern would look that comes from partitioning the orange parcels in this manner, using the condition of "lies within 50 feet of an historic district" to do so.

This sort of partitioning of parcels, based on policy, is very easy to do.  The reason it is easy is that the parcel boundaries are already digitized at a level that is satisfactory for official use.

WHAT MIGHT BE MOST USEFUL, to the modeling effort HERE,

• WOULD BE TO CONSIDER, IN THE MODEL, CONSTRUCTION GUIDELINES ON BREAKPOINTS BETWEEN BUILDING HEIGHTS
• WOULD BE TO KNOW IF SOME PARCELS, EXCLUDED IN THIS MODEL BECAUSE THEY ARE NOT CURRENTLY ZONED FOR PREMIUMS (SUCH AS IN THE LIBRARY BLOCK), WILL BE ADDED TO BE INCLUDED AS PARCELS TO BE ELIGIBLE AS TARGETS OF OPPORTUNITY FOR EXTRA HEIGHT.

Another example of just sorting existing layers in various ways might come from looking at the DDA buffer zone of 1/4 mile (distance one might reasonably be expected to walk to a bus stop--or a DDA-perimeter bus stop).  It's easy to pick out the vacant parcels, from the set supplied by planning, that lie in the buffer and do not lie within the DDA or within historic districts (other conditions would be easy to add on or alter)--these parcels are shown in gold, below.  It's also easy to select, from this latter set, only those parcels that are more than 1/3 acre in size (shown in red below)--or whatever existing conditions tell us what is, and what is not, a buildable lot (shape, size, adjacency to zoning types of various sorts, or whatever--then it is easy to exclude those parcels if the data is there, once decisions are made).  The animation below shows first, all vacant parcels that lie within the 1/4 mile buffer zone (orange stripes), outside the DDA (regulatory mechanisms differ within and outside the DDA); then, all parcels of the latter sort that do not lie within existing historic districts; then all parcels of the latter sort that are more than 1/3 acre.

Here is a link to a VR model including all red parcels, both within the DDA, as red parcels below, and in the 1/4 mile buffer, as below, extruded (entire parcel) at the level of six stories).  It also includes the footprints file extruded according to actual height.

WHAT MIGHT BE MOST USEFUL, to the modeling effort HERE,

• WOULD BE TO KNOW WHAT CONDITIONS THERE ARE ON WHAT CONSTITUTES A BUILDABLE LOT SIZE OR SHAPE (TIED TO USE, DESIGN, OR WHATEVER)
• TO KNOW WHAT REGULATORY MECHANISMS WILL CONTROL WHAT HAPPENS ON THESE PARCELS, IN TERMS OF ZONING, HEIGHT, PREMIUMS, FAR, SETBACKS, AND SO FORTH.
• TO KNOW WHAT FIRE REGULATIONS (TOTAL PERSONNEL OR INSURANCE CONCERNS) COME INTO PLAY AND HOW THEY MIGHT INFLUENCE WHERE PARKING CAN OR CANNOT BE PLACED.

2.  Next.
Extrude the parcel set from above and create a VR model.  What is required to extrude, in addition to having the right software, is to add new columns to the parcel database that reflect new decisions on heights.

3.  Then next.
Make animations from the VR models--requires adjusting the code underlying the VR model and setting viewpoints to be consistent throughout a sequence of VR models.  Once code is adjusted, then go in to each VR model to the appropriate viewpoint, do a screen capture, and assemble the sequence of screen captures and set timing as desired between successive animation frames.  Introduce "tweening" if desired to gradually fade from one frame to the next.

4.  Most time consuming.
Digitizing of building footprints.  Thus, issues involving setbacks are the most time consuming.  There are ways to make this quicker, if the footprint size is viewed as a percentage of parcel size.  For example, at footprint size = 100 percent of parcel size, a building of 6 stories might be built by right on one parcel if its FAR were 600%; if the building footprint is reduced to 50% of the parcel area, then a building of 12 stories might be built by right using the 600% FAR; if the building footprint were 75% of parcel area, or 3/4, then a building of 4/3 height, or 8 stories (6 + one-third of 6)=(6+2)=8--hence the rectangular hyperbola of a previous link) might be built by right using the 600% FAR.

So, it's not too time-consuming to digitize part of a lot and make the resulting area approximately half or three quarters of the parcel area.  It's a lot more time-consuming to specify exactly where the building can be placed in that 50% (or whatever) through specifying setbacks.  On the other hand, it may be that it is well worth expending that time, in terms of making decisions defensible.  Just explaining it so the tradeoffs in timing are displayed.

Shadows might be digitized--most desirable would be to have the software create them in response to changing lighting conditions (which can be set by position of sun in the sky--height, as a function of latitude, and direction, by cardinal point on a compass).

Incorporating UM information is of unknown difficulty...need to see files first.

Greater input from the Taskforce provides greater information from the modeling.

Sandra Arlinghaus

Solstice:  An Electronic Journal of Geography and Mathematics, Institute of Mathematical Geography, Ann Arbor, Michigan.
Volume XV, Number 1.
http://www.InstituteOfMathematicalGeography.org/