The Need for Comprehensive 3D City Models (Part 2)

In my last post, I talked about some of the more important communities of interest that have needs for comprehensive 3D city models.  In this post, I will try to think through what the most common use cases are that would be helpful to users of 3D city models regardless of their specific interests.  In the final post of this series, I will describe some of the tool sets that we need to author, publish, and consume these models effectively.

Common Use Cases

Now that we have identified a few of the more important communities of interest that have a need to understand the complexities of our urban environments in 3-D over time, let's try to identify some common functionality and usability requirements. If we can identify common sets of requirements across user communities, then we have the ability to start designing data models, data management systems, authoring and analysis tools, and publishing and data sharing strategies that might be effective across communities.


Visualization is huge.  Many excellent books have been written on various aspects of visualization. In the 4D urban environment visualization is particularly interesting and complex. In the context of the various communities of interest that we have identified previously, there are a number of visualization requirements patterns that emerge:

  • The need to visualize at a range of geographic scales - we need to be able to visualize our urban environment from a regional scale down to the corner of a room.  While it is not always necessary to visualize in 3-D, it is usually the case that some indication of elevation is an integral part of the visualization user experience. For example, if I am visualizing a floor plan in 2-D it is important for me to understand whether I'm looking at the first floor where the 15th floor.

  • The need to visualize at various levels of detail - for some uses, it is most appropriate to symbolize a building is a large single rectangle or mass. For other uses is necessary to have a more complete architectural rendering of the building including a photo realistic texture.  It is also important to have the ability to have different representations of buildings depending on whether you are modeling day or night scenarios, seasonal scenarios, or perhaps an infrared visualization of buildings.

  • The need to visualize changes over time - whether it is the addition or removal of buildings in the landscape over a relatively long time scale over the changing temperature patterns within a room throughout the course of the day, being able to visualize the variable of time is a common requirement across almost all of the communities of interest that we have identified.

  • The need to visualize different building components - for some workflows it may be appropriate to visualize and symbolize entire buildings, for other workflows it may be necessary to visualize individual rooms or collections of rooms, for other workflows it may be necessary to visualize individual items within a room.

All of these requirements need to be met within a user experience that is intuitive and performs well.

Line of Sight Analysis

There are a number of communities of interest that need to be able to perform variations of a line of sight analysis.  The security community probably has some of the most pressing and interesting requirements for line of sight but certainly the planning community and land-use entitlement community has requirements for this as well.  Requirements for line of sight analysis include:

  • Dynamic view shed analysis (who can see me along this proposed route?)

  • Static view shed analysis (what can I see from this vantage point? Needs to work from a point in a room through windows.  Also needs to work inside buildings)

  • Shadow analysis (What is the shadow pattern cast by this proposed building?  Needs to take into account time of day and season)

3D Buffer

Almost every community has some sort of requirement for 3-D buffer analysis.  Whether it is trying to determine which spaces will be impacted by a certain type of blast, which vacant offices are within 1000 feet of a parking lot, or which spaces would be impacted by a change in zoning ordinance, 3-D buffer analysis is a ubiquitous requirement.  3D Buffer needs to include persistence of the buffer and selection functionality.  Requirements for a 3D buffer analysis include:

  • Buffer from a user-defined point - Let the user define a point in 3D space and specify the buffer distance to be visualized and which features are to be selected.

  • Buffer from a selected set - If the user has identified a selected set of objects, the 3D buffer should work from the selected set.

3D Addressing and Routing

3-D addressing and routing is a particularly keen interest of the college and university communities currently. There have been a number of high profile lawsuits brought against universities that were not fully compliant with the Americans with Disabilities Act (ADA).  The subsequent fines and construction projects required to bring those institutions fully into compliance with ADA have really focused the community on better understanding the impacts of routing yourself from one room to another on-campus if you are disabled. Public safety also stands to gain from better systems for routing and addressing inside buildings. By using in building transportation models, public safety planners can better understand how to operate in specific buildings and how best to design effective evacuation plans.  A new law in Massachusetts requires that any building owner with a PBX system must resolve a suite or room number to state-wide 911 centers to aid in dispatch inside buildings.  3D addressing and routing functionality should include the following:

  • Ability to address each door to a space - this is important for evacuation routing purposes

  • Locators customized to in-building addressing patterns - important for establishing the "from" and "to" points on a campus route

  • Ability to include access restrictions along a route (weight restrictions, door width restrictions, handicap access restrictions, etc.)

  • Ability to create multi-modal routes within and between buildings for human and equipment trasportation - particularly important for handicapped accessibility issues as well as materials handling

4D Sensor Information Management

The Security and Environmental Monitoring communities share the most direct requirements for 4D sensor modeling and management. That said, there is a growing industry focused on monitoring the locations of critical infrastructure within the facility, like crash carts in a hospital for instance, and even the locations of personnel in certain situations.  4D sensor network integration requires the following:

  • Data models that support a variety of sensor information packets being tied to stationary and mobile sensor platforms

  • A common set of sensor data communication protocols to communicate this information securely over open networks

  • An Enterprise Service Bus architecture that provides the ability for systems to securely subscribe to sensor feeds.

  • Desktop, web, and mobile clients that are capable of managing 3D data with a temporal dimension in an intuitive user interface

Enterprise Systems Integration

For most of the communities of interest that we have identified, their primary business information system is not a GIS. That said, by leveraging the power and geospatial analysis capabilities of a GIS and a comprehensive 3-D city model, these communities can derive  valuable new understanding of the geospatial patterns that exist within their current business information systems. A partial list of enterprise systems that could benefit by being spatially enabled with a comprehensive 3-D city model might include:

  • Municipal CAMA systems for taxation

  • Computer Aided Dispatch for Public Safety

  • Computer Aided Facilities Management

  • Work Order Management

  • Energy Performance Monitoring

  • Environmental Quality Sampling

  • Closed Circuit TV Management and Monitoring

  • Commercial Real Estate Portfolio Management

  • Municipal Inspection and Violation Systems

Mobile Deployment

Many of our communities of interest would benefit from the ability to access a 3-D city model in the field. This capability would be particularly useful to the security, public safety, facilities management, environmental quality, and municipal inspection communities.  We are already starting to see demand for consumer applications of 3-D city models. There are some very interesting iPhone applications that have been released in the past few months that allow the user to visualize the city in 3-D on their handheld and to query the system for information about items that they see around them.