3D Stereo Imagery as a Right of Way Tool for Access Permitting
Joel Hearne, SimWright, Inc.
This report and 2 CDs were distributed to each Division Office on June 14, 2005. Additional copies of the CDs may be made through your local Division Realty Officer.
Research Results
Rapid growth and development in the United States have highlighted the critical necessity for intelligent management of roadway access. As our populations and communities continue to grow, our transportation infrastructures sustain ever-increasing traffic volumes. This has amplified the impacts of transportation decision-making and has brought about a paradigm shift in the way that the flow of traffic is managed. Transportation planners, policy makers, and engineers are gradually realizing the importance of Geographic Information Systems (GIS) for improving roadway access.
Access management standards have been around for years with varying levels of success. Recently there has been a trend toward the development of more effective management of driveways, medians, median openings, traffic signals, and freeway interchanges[i]. This movement has resulted in the publication of the authoritative guide for "Access Management Manual", published by the Transportation Research Board (TRB) committee on access management.
Access management involves a diversity of transportation disciplines including: engineers, planners, permit reviewers, politicians, developers, and the public[ii]. It focuses on the safety, efficiency, and aesthetics of driveways, medians, median openings, traffic signals, and interchanges[iii]. The recent movement towards standardization and dissemination of access management principals has created a greater understanding and awareness of this important issue. A synergistic dynamic is realized when GIS technologies are used for the application of access management principals.
Good access management requires a solid geo-spatial and temporal understanding of the area being managed. Aerial photography and GIS can be important access management tools. This paper describes the results of research and development efforts aimed at applying emerging GIS technologies to access management problems.
SBIR Effort
In February of 2000, Federal Highway Administration (FHWA) issued a research topic under the Small Business Innovative Research (SBIR) Program seeking innovative approaches to the driveway access permitting process. SimWright, a geo-spatial technologies firm, and HSA, a transportation-engineering firm, conducted the research and development under this SBIR grant to develop e-permitting, GIS, and 3D aerial photography technologies for better access management. The result of this work is a prototype system that uses digital 3D aerial photography to extract spatial data related to driveway permitting and access management[iv]. The system also provides for automation of the permit application and review process. This work was carried out with the premise that data automation and GIS integration will improve the driveway permitting process, thereby improving access management practices at the permitting level. The original inspiration for this research was to create a mechanism by which spatial access management data could be collected in an efficient and standardized manner. Driveway permitting processes act as a vortex for access management related data. This was the motivating factor for approaching the project from a permitting standpoint.
GIS Technologies Research Findings
Reducing the overhead cost of access permitting was a principal motivator throughout the project. Ideally many hours of monotonous access permitting tasks will be avoided via automation using GIS, the Internet, and relational databases. Permit reviewers will have more time to process more information to make better access management decisions. National trends towards standardized GIS databases and GIS technical standards are further increasing the return on investment for exploiting GIS technologies[v]. Interoperability of spatial data formats is making it cheaper and easier for organizations to do business.
Many access permitting tasks can be optimized by GIS innovations. The TRB access management committee’s "Access Management Manual" outlines some characteristic considerations for access permitting[vi]. Applicable GIS technologies are shown in Figure 1 for each of these considerations.
| Consideration | Method(s) of Spatial Representation |
|---|---|
| Driveway Location | Linear Referencing, Point, Polygon (site design) |
| Total Number of Driveways | Described as Driveways per Linear Unit |
| Driveway Radius and Width | Proposed Site Plans and Image Feature Extraction |
| Auxiliary Lanes | Proposed Site Plans and Image Feature Extraction |
| Driveway Profile | Proposed Site Plans and Image Feature Extraction |
| Sight Distance | Proposed Site Plans and Image Feature Extraction |
| Circulation Pattern | Proposed Site Plans, Image Feature Extraction, Site Visit |
| Projected Conditions | Linear Referencing, Cadastral, Demographic, Scenario Driven GIS Models |
| Physical Construction Design | Site Plan |
| General Considerations | Maps, Drawings, Web-Based Database, and GIS Portals |
Figure 1 - GIS Methods for Some Permit Considerations (considerations taken from TRB "Access Management Manual")
Different access review and analysis needs require varying degrees of precision and resolution of spatial data. Some micro-simulation models require detailed driveway configurations, while regional traffic studies might require only points to symbolize driveway locations. In contrast transportation engineers require precision physical measurements, often within 1/100" of a foot. Collecting spatial data from the permitting process and the use of precision 3D imagery improves the outcome of permitting decisions and the collection of quality spatial data for access management applications.
Three basic data models are used in access management GIS applications: linear, cadastral, and physical. Roadways are often symbolized as linear routes by which roadway features, such as driveways, are expressed as points or ranges along these routes. Many state transportation agencies maintain roadway characteristic data in this manner. Florida’s Roadway Characteristics Inventory (RCI) maintains over 240 such roadway features ranging from traffic signals, to functional classifications. The use of cadastral data such as property and land use boundaries has proven valuable to access management tasks such as trip generation, conceptual review, and right-of-way acquisition cost estimation. Site-specific data needs require a solid understanding of the physical geography of the area. Engineering site plans, detailed topographic representation, and aerial photography are integral components of site review. The combination of these three data models provides a synergistic analysis environment for access management professionals.
Technologies Developed
Web-Permitting
A primary component of this research effort is a web-based permitting system that includes GIS integration. The prototype implementation of this system is the Automated Driveway and Access Management (ADAM) System. The ADAM System consists of a central repository of permitting and GIS data, electronic application and review forms, and web-based GIS interfaces. Electronic forms are automated to minimize data entry overhead, and spatially validate permit requirements. Internet GIS modules support common tasks for permit reviewers and applicants. ADAM also integrates local county property data, aerial photography, and State DOT roadway data.
The pilot project involved the conversion of existing driveway permit records into GIS point data that is spatially referenced by roadway and milepost. The driveway permit locations have been made Internet accessible via an Internet Map Service (IMS). This map service shows permit locations in conjunction with features such as: property boundaries, roadway centerlines, functional class, signal locations, and aerial photography. Users can query spatial data in the map service by spatial proximity, attribute data, or combinations of the two. This enables analysts to better understand relationships between driveway permits, land use, and other roadway related features.
The ADAM web application includes electronic permit application forms that integrate GIS components to facilitate the application process and data collection. Unlike typical electronic forms permit data is written to a central database and linked spatially to the ADAM GIS system. In addition, spatially linked blocks of permit application information can be added to forms automatically through custom GIS queries. For example, all relevant property information can be added to the ADAM database and permit form by locating that property on the map. All of the relevant information associated with that parcel is then pulled into the application form. This concept is taken a step further by using spatial proximity analysis to locate other features such as nearby roadways and intersections for incorporation into permit application forms. This reduces the time investment for completing permit applications, automatically validates application information, and ensures that accurate permit spatial data will be archived.
The web-based permitting process is further augmented by the integration of 3D site analysis and visualization tools.
Web Portal for Precision Stereo Imagery
Costs of acquisition and maintenance of 3D stereo imagery typically increase exponentially with resolution, fidelity, and precision of the collected data. However, distributing collection and implementation costs among potential stakeholders can increase the availability of quality data.
The prototype 3D web portal enables users to make precision horizontal and vertical measurements from precision 3D aerial photography over the web. Innovations in compression technology and expanded information infrastructure have made it possible for the GIS layperson to rapidly access datasets that where previously inaccessible due to prohibitive file size and bandwidth. Users can view the imagery using very inexpensive glasses with red and green lenses, known as the anaglyph viewing method. A more advanced method, known as stereo, is also available where relatively inexpensive hardware typically used in virtual reality applications and video gaming is used for 3D rendering. These viewing methods give casual GIS users access to 3D imagery without the need to absorb all of the hardware and data management costs associated with collecting, processing, and storing 3D imagery.
3D GIS feature extraction tools have also been developed for the creation of GIS data layers such as roadway curbs, centerlines, driveways, spot elevations, and parking lot boundaries. Feature extraction from traditional aerial photography, known as orthorectified imagery, is inherently inaccurate and does not retain data fidelity. Collection of features in 3D from unaltered imagery ensures maximum precision of extracted features.
Many access management permit reviewers find it difficult to incorporate emerging technologies into their workflow. Nevertheless, permitting professionals are making time to adopt the new, workload reducing GIS tools. Data products derived from 3D imagery, such as Digital Elevation Models (DEMs), drainage analysis, site maps, and 3D visual simulations are often of greater interest for permit reviewers. This data must be integrated into an easy to use GIS framework for permit reviewers and permit applicants. This requires a well designed spatial database architecture as well as simple and logical graphical user interfaces (GUIs).
The most innovative development from this research effort has not been technically complex software, but rather the realization of the need for extreme simplicity in building user interfaces. Early versions of the ADAM system incorporated all available web-based GIS tools into a single interface. User responses have improved proportionately to the simplicity of the user interface and pertinence to the task at hand. The goal of this research was to build tools that use GIS technologies for non-GIS users.
The 3D web-portal concept has already proven useful for data sharing, GIS feature extraction, volumetric analysis, 3D visual simulation, and Access Management analysis.
Innovative Data Collection Software and Techniques
Stereo-photogrammetry has been in use for over a century. Recent innovations in digital camera design and GPS technologies have reduced collection and processing costs. Traditional aerial photography incurs significant overhead for making it GIS capable. Digital aerial photography technology incorporates precision GPS systems that account for inertia of the camera and inconsistencies in flight path with ever increasing levels of precision. This greatly reduces the cost of referencing the image to spatial coordinate systems for use in GIS systems. SimWright, Inc. and HSA, Inc. have teamed to establish mathematical algorithms by which aerial images are spatially correlated to derive precision horizontal and vertical measurements. SimWright has also developed a 3D GIS platform, called StereoGIS, designed specifically for extracting features from 3D aerial photography and satellite imagery. Data production teams use StereoGIS to create digital elevation models (DEMs), 3D cultural features such as roadway curbs, driveways, and parking lots.
Technical advances have improved data collection and processing techniques for transportation related data. As a result, SimWright’s data collection and processing efforts are conducted in a more access management enlightened manner. The aspiration of these efforts is to collect driveway features in a way so they can be inexpensively incorporated into access management studies and analysis projects. The pooling of data collection costs among government agencies can further reduce the costs of spatial data collection and implementation.
Collection of GIS Data Useful for Access Management
3D aerial photography is an excellent source of raw information that can be used as a basis for the creation of precision roadway GIS data. This GIS data, if used properly, can be effectively applied to a multitude of access management related tasks ranging from micro-simulation to driveway permitting. An often-overlooked benefit of GIS in access management is the ability to spatially relate separate datasets. For example, driveway permit data can be related to property data by attributes such as site address or property identification number. These joined datasets can then be spatially associated with roadway features such as driveway and parking lot boundaries. The end result of these technologies is a set of geospatial power tools that can be used to improve access management decision-making and analysis.
Conclusion
Many technologies and methods were created, explored, and tested in the research and development of the ADAM prototype. The result of this work is robust software architecture for web-enabled 3D imagery applications, and a GIS enabled e-permitting system. Many components of the ADAM prototype have already been applied in commercial projects. Interaction with a wide variety of access management practitioners has also improved the manner in which SimWright and HSA design transportation related databases and software applications. The stage is now set for geospatially informed Access Management decision making.
The ADAM CD contains information regarding the software that is available commercially from SimWright, Inc.
References
[i] The Access Management Committee (A1D07) Ronald K. Giguere, FHWA, Access Management in the New Millennium, TRB Whitepaper
[ii] Transportation Research Board, Third National Access Management Conference, Conference Proceedings, Introduction
[iii] Florida Department of Transportation, Systems Planning Office, Introduction to Access Management, Powerpoint Presentation
[iv] SimWright, Inc., FHWA SBIR Research Topic 00-FH4, Research to Develop a 3D Terrestrial Imagery User Interface for Driveway Access Management, Final Report
[v] Eliane Silva, Cost-Benefit Analysis for Geographic Information Systems, March 1998
[vi] Transportation Research Board, Access Management Manual, pg. 217, figure 12-1
