Overview

• Quick tour of terrain models using ArcScene and a 'hillshade' map of Boston
• Introduction to Community Viz scenario modeling extension
• Lab Exercise: East Boston housing value model and MetroFuture (Community Vix) model of Boston growth

Lab #6 will be more open-ended than the previous 5 labs. The idea is to suggest several paths that build on what we have done in previous labs. One theme is to build on the visualization of East Boston land and housing values. A second theme is to expand our use of model building tools to include expanded datasets and spatial analysis interactions in our examination of metropolitan growth and redevelopment.

Modeling Housing Value in East Boston

Lab #5 demonstrated some raster techniques that helped us interpolate residential sales data from East Boston to develop a housing value 'surface' for East Boston. However, the visualization was not particularly satisfying since the number of sales was relatively small and the variation in house cost/size sufficient large to yield surface that is more bumpy than we might consider realistic. Here are a few additional steps that you might try.

(1) Use the 'zonal statistics' tools to aggregate, at the block level, the housing values estimated from the raster surface that you developed in lab#5. (Instead of averaging the sales prices you may want to consider the assessed value per gross square foot (as computed in the exam), plus perhaps, the land value per square foot of lotsize.) Use the East Boston block shapefile that you generated earlier from the parcel map. Do this using the zonal statistics wizard from the 'spatial analyst' menu since doing it from the toolbox may not let you join the result back to the East Boston block shapefile. Only consider blocks that have some minimal amount of housing on them - e.g., do not include the airport blocks.

(2) Once you have averaged the residential housing value for each block and joined the result to the block shapefile, you can thematically shade the blocks to get a housing value map. Copy this layer (and the parcel and building layer) to ArcScene and extrude the building footprints and the blocks to a height proportional to the roof heights (for footprints)and averaage residential values (for blocks). Make the footprint layer semi-transparent. Can you get a visualization that is not too cluttered and conveys a sense of housing value as well as massing?

(3) Try to add these steps to the Model Builder model that you started in Lab #5.

Terrain models using ArcGIS and ArcScene

We have mentioned but not yet demonstrated the use of terrain models to handle non-flat surfaces. If we had a terrain model for East Boston, we would see the effect on land and housing values of the hills along the northeast and southwest of East Boston. In lab today, I'll illustrate the use of digital elevation models for 2-D 'hillshading' and walk you through this short exercise that uses a TIN (triangulated irregular network) surface model of Boston. (Unfortunately, we have the TIN model only for the 'mainland' part of Boston - not for East Boston. You can build a TIN for East Boston using the Digital Elevation Model and Contour Maps available from MassGIS: http://www.mass.gov/mgis/laylist.htm)

• How the Boston TIN was constructed
  • Build TIN from digital elevation model
    • connect triplets of elevation points to form planar triangles
    • thin out the triangulated network to form larger triangles where nearby elevations/slopes are similar
    • this triangulated irregular network models the surface as interconnected planar triangles.
  • Shade each triangle in the TIN using a color based on elevation and darkness based on slope/aspect (usually relative to 'sunlight' from the northwest side)
  • Display the TIN in ArcMap and/or in ArcScene and overlay other vector coverages
• Your Exercise: (Short and easy to do today though you can turn it in on Tuesday after Spring Break)
  • Load into ArcMap the Boston TIN layer in the class locker: .\data\bostin\hyp_bos_tin (FIRST, copy the entire BOSTIN directory tree to your local drive.)
  • Zoom in and view the layer properties to examine the data structure - do you see how the color and shading are done?
  • Start ArcScene and load the same Boston TIN layer.
  • Experiment with the 3D interface
  • Add an additional vector layer - try the road layer in the same bostin directory
    • Adjust the symbology to make the major roads wider, etc.
    • Adjust the 'base heights' properties of the layer so the roads are draped on top of the terrain (notice that roads beyond the bostin extent disappear once you do this)
    • Note some of the other layer properties and ArcScene features (e.g., you can export a VRML file - virtual reality markup language form of the 3D scene)
    • Turn in a screen shot of Boston with the major road layer draped on top

Modeling Metropolitan Growth and (Re)Development

This section introduces you to the 'Scenario 360' part of a modeling tool called Community Viz that is a substantial 'extension' the ArcGIS and that was orginally financed by the Orton Foundation. Community Viz is a little like Model Builder. That is, you use it to develop a model as a sequence of interconnected ArcGIS spatial data processing steps. However, Community Viz goes further than Model Builder in providing analytic formulas for modeling complex interactions and wizards and tools to help in building and running the model. Community Viz also focuses on scenario modeling - that is, playing out the long term consequences of growth and development in the face of various constraints and interactions regarding land use, accessibility, environmental constraints, and the like.

The oingoing MetroFuture regional planning effort for metro Boston has been using Community Viz to model Boston devleopment out to 2030. The Metropolitan Area Planning Council (MAPC) is the organization that has built this model and has arranged for MIT to have 21 floating licenses to run it. The Boston MetroFuture model is available for our use but is too complex to serve as a useful introduction to Community Viz. It will be available later in the semester if it proves useful for our project work.

(1) Skim the scenario 360 tutorial in the 'proj08' portion of the class locker: "K:\proj08\CVFiles_metro\Scenario 360 Tutorials.pdf"

(2) Read the Your Guide to "Winds of Change" document in the class locker: K:\proj08\metrofuture\explore_scenario_woc.pdf This document explains one of the four scenarios that MetroFuture modeling using Community Viz. The 'indicators' and 'drivers' on the last few pages are the assumptions and key relationships in the Community Viz model that explain the results of modeling the effects of a 'winds of change' strategy for metro Boston growth out to 2030.

(3) * Since the MetroFuture model is quite complex, start first with one of the Community Viz 'tutorial examples'. I will illustrate 'Communityville' during the lab and, if the lab machines will run Community Viz today!, you can try it as well. BEFORE RUNNING ANY COMMUNITY VIZ MODEL, be sure to copy the entire CVFiles directory tree to a local, writeable drive.

(4) * Start Community Viz - Scenario 360 from the Start/Community-Viz/Scenario-360 menu on the WinAthena PC. Once ArcGIS comes up, you will see a new toolbar for scenario-360 and a dialog box asking you to choose the saved analysis you would like to open. Browse to your local copy of Communityville and select it. Rerun the model after adjusting the assumption about distance from bird nest. Note the reduction in allowed development that is computed and displayed as the distance-from-nest assumption is adjusted. Explore the diagram and formulas that codify the spatial and mathematical relationships.

(5) * If Start/Community-Viz is missing, you may need to reboot the machine. Also, after Communityville has been opened inside of ArcGIS, you may see a message indicating that ChartFX is not working. In this case, exit from ArcGIS since CommunityViz will not work. The machine needs to run an 'msi' installation file in: C:\Program Files\CommunityViz\Scenario 360\ChartFX\ChartFX.msi Unfortunately, you do not have permission to run this file (otherwise you could just double-click on the file to run it.) Depending upon the order of consideration of bootup files, these charting tools occasionally do not work. If you reboot the machine, the 'msi' file may get run properly during the bootup. After running ChartFX.msi, go back to step (4) to restart CommunityViz.

(6) * To run the MetroFuture model, copy the entire directory: K:\proj08\CVFiles_metro to a local, writeable directory. Then start CommunityViz as before (or start ArcGIS, make sure the CommunityViz extension is loaded and viewable, and choose scenario-360/analysis to browse to your local MetroFuture_BCCS_may2007 location).

(7) * Explore the effects of changing some of the assumptions for water or type of housing. (Rerunning the model after you have changed these assumptions takes some time, but much less than changes in many other assumptions.)

* The CommunityViz extension to ArcGIS is installed in CRON machines in building 9 but not in computer lab in Room 37-312. So we will demo and test CommunityViz on Thursday instead of today.

What to turn in

All that is required for this lab today, is the screen shot of the Boston terrain map that you developed in the second part. The rest is for your exploration. We will have some additional time for the CommunityViz exercise in lab on Thursday. (Otherwise, for the remainder of today's lab and outside of class you should be working on your Problem Set B).