Metropolitan-Scale 3d Models at the GSD

Retrieving Scenarios from the Metropolitan Model Repository

This page introduces the Harvard Graduate School of Design's infrastructure for building and using a metropolitan-scale three-dimensional urban model. We will begin by discussing the resources upon which this model is built we will take a look at how the data are stored, then we will have a look at how elements of this model can be extracted from the repository to create off-line versions of parts of the database that can be used for visualizations of parts of the city under different historic or future design scenarios. This is the first in a series of pages that will discuss how the repository can be used to create 3d models for editing in sketchup or export to google-earth, how articulated models may be transferred from sketchup into the shared repository, and how these resources can be used for analytical studies such as view-corridor analyses.

Documentation

The GIS resources and tools described in this document can be used without much knowledge of GIS. If you are interested in how these resources and procedures were put together, you should take a look at some of the GIS user manuals:

Using ArcMap for background on GIS data layers and attributes, and how to navigate in the ArcMap interface.
Geoprocessing in ArcGIS Especially for background on setting the geoprocessing environment for Output Extent.
Using ArcMap 3d Analyst for information about Creating Surface Models

Information Resources

Much of the information that enables our compilation of geometrically correct landmark models comes from a LIDAR survey of the Boston Area that was flown by the Massachusetts GIS in 2001. This survey amounted to the 3d scan of the city that collected the heights of everything on the ground at a resolution of 1 meter. A portion of this survey was turned into vector-based building roofprints each having attributes for their roof height and footprint elevation. MassGIS has also made available color orthophotography for the region at a pixel-resolution of one-half meter. In addition to this, we also use the MassGIS 1:5000 digital elevation model, in which the height of the terrain is given for each 5 meter cell.

The extent of this three dimmensional model stretches from Everett to Roslindale, including all of Boston, Brookline and Cambridge.
We also have a general terrain model representing the lay of the land without buildings at a resolution of 5 meters per pixel from the Elevation Layer.
The ground condition is further articulated with an half-meter orthophoto from MassGIS.
The LIDAR First Return provides a detailed raster model of the heights of everything.
These data were further processed (in a process that was fairly labor intensive) to extract Roofprints with the roof and ground heights of the basic massing volumes of buildings.
More detailed, actual 3d models, collected from various sources are also bart of our database. These are in the MultiPatch Layer.
Finally, because multipatches and roofprints often conflict with eachother, we have a Substitutions Table to keep our scenarios succinct.
These independent datasets can be combined to make a rough 3d model of the city.

Scenario Selection and Rendering

Having All of these models in a large, scaleable database schema allow us to use database logic to retrieve logically consistent views of the city based on past, present and future conditions. Any numer of different thematic views may be drawn upon -- including commercial or emergency management themes.

The present context of Gund Hall
The 1999 context of Gund Hall
The Query for retrieving the 1999 Scenario
Gund Hall Proposed Scheme A (Thanks to Ignacio Paliza.)
View from the 5th floor of Scheme A

This is a very large amount of data, which would be very awkward to deal with as files. We are assisted by the GSD's enterprise-scale GIS database -- Spatial Data Engine -- which uses an Oracle database server to store and retrieve data requested by ArcMap and ArcGlobe. We have developed an ArcMap project that links to all of these datasets, and has some tools that will extract all of the layers for a user-defined area.

Download and explore the Metropolitan Model Archive Tools

You may access this entire metropolitan dataset (if you are on the GSD's network) by excecuting the following steps:

Right-Cick this link open this zip archive and extract its contents to your c:\temp directory.
Use windows explorer to check out the contents of your new metromodel folder. If you are interested, take a look at the readme.txt file which documents the contents of this archive. Note the contents of the clip folder with its toolbox and the boston folder that contains basic layers and another toolbox file.
Double-click on the ArcMap document, boston_metro_2d.mxd to start arcmap with this prepared document that links layers the GSD's Spatial Data Engine server.
Explore these layers, by zooming in and out and panning. Notice that the building roofprints don't draw unless you are really zoomed in. There are multipatch objects around the area of the bigdig, gund hall, and fenway park.
Choose View->Bookmarks->Gund to zoom to the neighborhood of the GSD Notice how there are some roofprints and some multipatch objects all overlapping with eachother.
Take a look at the attribute tables for the various layers.
Poke at each layer with the information tool to dynamically see the attributes of specific vector objects or raster cells.
Use the tabs at the bottom-left of your window to set your table of contents to Source view and open the Substitutions table. It records the correspondence between multipatch objects and roofprint polygons.

Extracting Local Clip from the Model Repository

The data layers connected to our Boston_Metro_2d data repository represent a 3d model of the city, but this model is rater awkward to visualize in a three dimensions all at once -- it can be done, but but it is not recommnded for casual introductory exercises such as this. So our first goal will be to extract a local clip of the data to our local hard drive. This will allow us to explore the model with more flexibility, and to serve as a base for our model improvement efforts.

The clip procedure amounts to choosing an area by zooming into it, and then cutting out each raster layer based on this area, selecting all of the roofprint and multipatch objects within this clip area, also the records in the Substitutions table that relate to objects within your clip extent. Al of this is written into the clip folder, which can then be a fre-standing copy of the model database that you can copy and take with you! bAll of these procedures have been encapsulated in a geoprocessing model that will be found in the the toolbox, Clip_Context.

Make Your Clip Dataset

Use Tools->Extensions to enable the Spatial Analst and 3d Analyst extensions.
Make sure you are zoomed into a relatively small area. For this demo, let me suggest the area covered by the Gund Hall bookmark.
Find the toolbox, Clip Context and double-click on its model, Clip_Data.
You will be offered a dialog to set the model's parameters.
Make sure to set the >Output Extent option to "Same as Display" or else you will be attempting to download the entire metropolitan dataset to your hard drive, which will lock up your computer.
Click OK, then click ok to delete the Clip folder (twice).
Wait for the procedure to finish, then click close

The preceding sequence of steps has produced a TIN model aand made clipped copies of your LIDAR dataset, the building footprints and the raster terrain model. It would be good to have an image to drape onto our terrain when we make 3d models, so the next step will allow you to compose a map image and export it as a georeferenced JPEG image. We do this step outside of the ClipData model because it is much faster, and it will allow you to compose the image with whatever GIS datalayers and resolution you wish.

Exporting a Clipped Image

Turn on or Off any layers you want or don't want in your image
Choose File->Export Map
Set your Files of Type to export a Jpeg image and set your options -- especially the Save World File option as shown in this screenshot.
Save the image to your Clip Folder as map_image.jpg.
If you want this image to show up in ArcGlobe you will need to use ArcCatalog to set its Spatial Reference Property. to Massachusetts State Plane Mainland Zone, on the North American Datum of 1983. The easiest way to do this is to import the coordinate system from one of your existing layers as shown in this screen shot.

Your New Database

The previous process started by wiping out the existing clip folder, replacing it with a copy of the empty clip_template, which contains an empty personal geodatabase and ArcMap and an ArcGlobe documents ready to recieve the clipped data layers. Now if you take a look in the clip folder you will see that it has several new files in it. We will make our own copy of this new database, before exploring what it contains. Your copy of the clip folder is a self-contained GIS database that you can move anywhere you want. The Data layers and the ArcMap and ArcGlobe documents and the toolbox file in here are all related to eachother through relative pathnames so you can put this onto your own drive and use without being connected to the data repository. The arcmap document is useful for editing datalayers when necessary, the ArcGlobe dosument is useful for visualizing the data in 3d. The Scenarios.tbx toolbox contains database queries for sorting out which elements from the database should be selected for viewing different historic or future scenarios.

Taking Posession of your New Data and exploring it in 2d

First we will make our own copy of the clip folder, and then we will explore our new data in 2d with arcmap.

Use windows explorer to look inside your clip folder.
Make a copy of this folder and name it something else (e.g. "Gund") make sure that you leave the existing clip folder, or replace it with a copy of the clip_template, otherwise the clipdata model won't run again.
Open the Arcmap document, clipped_2d.mxd Take a look at all of the layers. These are all basically the same as the layers that you examined from the repository, but they have been clipped.
There is one additoional layer, the TIN (Triangulated Irregular Network) layer, which is a triangulated representation of the terrain useful for exporting to sketchup (later). See picture.
Examine the attributes of the various overlapping multipatches and roofprints just east of Gund Hall. See how the multipatches are tagged with different min_dates and max_dates?
Switch your table of contents to "Source" and open your copy of the substitutions table. Take a look at the pairs of references to multipatches and roofprints here. Try to visualize how this table stores a substitution relationship between multipatches and roofprints.

Do it Again?

So, you see that the Clip_Context model creates a new GIS database in the Clip folder. If you want to create a new clip dataset, you should make a copy of your clip folder and create a new empty clip folder by making a copy of Clip_Template and renaming it clip. Note that you will have to quit all ESRI applications and close the clip folder in all of your explorer windows or else Windows won't let you do this.

Exploring your Data in ArcGlobe

In the next step we will look at the clipped data in 3d using the 3d GIS Viewer, ArcGlobe.

Creating Scenario Views in ArcGlobe

Double-Click the ArcGlobe document Clipped3D.3dd to start arcglobe.
The layers in this document reference your clipped dataset, but they need to be refreshed to clear any data that acglobe may have cached. So right-click on each layer and choose Refresh.
Zoom to layer on your othophoto.
For more references and tips for using ArcGlobe, see Developng Rough Massing Models in ArcGlobe

Install the Sketchup Plugin for ArcGIS

You will find sketchup installed on all of the public computers at the GSD, but because of peculiarities of the sketchup arcgis plugin, each user must install the ArcGIS plugin on the computer and load the special sketchup tool into ArcGIS. The resources and instructions for installing Sketcup and the ESRI ArcGIS plugin are available in the GSD software directory L:\public\software\winapps\sketchup\sketchup6. On lab computers, the sketchup extension has been downloaded, but it needs to be added to Arcmap by each user. The following instruction assume that the sketchup esri plugin has been installed on the computer already.

Loading the Sketchup plugin to ArcGIS

Choose Tools->Customize
Click the Toolbars tab at the top of the customize dialog then click Add from File button.
Find the place on your computer where you installed the sketchup plugin files -- which on public computers is c:\program files\arcgis\Sketchup6 On computers in room 516 this will be c:\program files (x86)\arcgis\sketchup6
Choose the file, FeaturesToSkp.dll
After you get a message that ArcMap has loaded the plugin, press the Reset button on the Customize dialog box.
You will now have an option in your toolbars menu for the Sketchup tools. Check it and the sketchup toolbar will appear with a single sketchup button in it.
If you have a sketchup toolbar that has no button in it,

Arrange Data for Export to Sketchup

To begin, we need to arrange our 2d data in ArcMap in preparation to exporting to sketchup. We will use the Current Multipatch View and the Current Roofprint View which were created with a model in the Scenarios toolbox. We will use these views to select the apropriate roofprints and 3d models to export to sketchup, along with the TIN (triangulated irregular network) and the aerial photo covering our study area.

Open the Clipped_2d.mxd arcmap document in your tutorial folder.
use the select tool to select the elements from the Current Roofprints View
Use the Add Data Button to add the image of the areial that you exported from ArcMap to your map.
Click the Export to Sketchup button and export the Roofprints extruding to the value of their Roof attribute. Export the Multipatches and the TIN, and make sure to export the Orthophoto Raster as a jpg.
This should give you a nice sketchup model of the existing condition with the aerial photo underneath.
Select the orthophoto, right-click on it, and chose Explode, to ungroup the image.
While the Ortho is still selected, right-click again and choose Texture->Projected to make this image projectable.
Pick the Paintbucket Tool from the toolbar, and hold the alt key to access the Eyedropper Tool. Click on the Orthophoto image to sample this as the active texture.
Now double click on the TIN, to open this group for editing, and triple-click on it so that all of its connected faces become selected.
Now grab the Paintbucket again and click on the TIN. YOu have now mapped the image to the TIN.
If you like, you can now right-click the TIN and choose Smooth-Soften Edges to get rid of those unsightly TIN-Edges!

The section below is under construction