As we close the semester with Project 5, you will begin to explore the possibilities of working with spatial data in three dimensions (3D) within a GIS. Although we barely skim the surface of 3D (pun intended) modeling, this should enlighten you about the various data types with which our 3D world can be visualized and analyzed, and the different applications available for this type of work.
In the previous projects we have progressed from representing the 3D world as a 2D surface within a GIS with the appropriate projected coordinated system and projection that minimized distortion to working through terrain analyses that relied on digital elevation models representing the baseline surface of our 3D world. The project work has also been conducted at various scales ranging from global (from the Netherlands to Madagascar) to regional and the neighborhood level based on project goals, project design, data availability and resolution, and computing power. Now, you will examine the urban area of Los Angeles on an even finer scale, at the building level. As you will see, 3D data is not only visually larger with height measurements and volumetric measures, but it also requires more processing and space on a GIS and takes some time to render. We therefore will limit the project work to a few buildings in downtown LA (DTLA) and on the USC University Park Campus (UPC).
The built environment, buildings and urban landscape, in 3D provides the opportunity to examine more nuanced spatial questions, such as what is the line of sight from the top of a building for safety and security? If a person is standing at a certain intersection or driving on a given street, can they see a billboard of a specified height? How tall does a cell tower have to be to provide coverage over the urban landscape? And of course, for developers, what is the tallest the next building can be without blocking the sights and sunlight of current residences?
Your first task is to visualize the City of Los Angeles building data in 3D by extruding the height of polygons. The building footprints, with height data, for all buildings within the City of Los Angeles were acquired from the City of Los Angeles geohub. A countywide dataset contains over 3 million features with approximately 60 attributes; the citywide dataset still contains over 1 million buildings though with fewer attributes. After being clipped to an area containing UPC and DTLA (the UPC_DTLA_Bldgs feature), the dataset contains just over 72,000 buildings. You will work with only the UPC_DTLA dataset.
You will select a few buildings of differing heights to work with and extract just these features.
Exemplars have been provided for WPH, SOS, the JEP House, Ahn House, and the United University Church on the USC UPC (UPC_DTLA_USC5Bldgs) and Dodger Stadium and surroundings (UPC_DTLA_DodgerStadiumArea). You will also create new 3D Multipatch features and complete the rest of the project work utilizing these features, an input TIN surface of the
UPC_DTLA study area that has been provided, and observation points to determine important features such as line of sight and skyline measures.
Assigned readings, resources, and web courses are chosen to help you understand and implement appropriate workflows. Data layers for the required visualizations are available to you on the SSI server (see below).
TIP: Save your work often and track your time working on the VM – recall you only have five (5) hours before the VM disconnects without warning.
TIP: Once again clear out your G: drive before beginning this project. Copy and save your previous work to an external (USB, hard drive, Google cloud) drive.