Unlocking the Wealth of Imagery
Arizona DOT and Sanborn Using ArcGIS Image Server
Both public and private organizations are finding that the volume of imagery available to them is growing at a rapid rate. At the same time, however, the importance of updated and current imagery, including aerial and satellite, is also growing. Decision makers in many organizations need the latest high-quality images to visualize and analyze activities such as land use, forest quality, military operations, and emergency situations.
Geographic information system (GIS) users are especially interested in the increasing availability of imagery. Whether serving as a natural background for GIS applications, as a vehicle for direct interpretation of data, as a basis for statistics and analysis, or as the source for many vector maps, imagery has many demands placed upon it. While huge volumes of imagery from many sources exist today, accessibility to this data is a challenge, and as a result only a fraction of what is available is actually accessed. Increasing access to the imagery increases its value, and since images are a snapshot in time, the faster they are made available, the more useful they are to those who need them.
Arizona's Multimodal Planning Division (MPD) of the Arizona Department of Transportation (ADOT) provides high quality transportation research, plans and programs to the public. "GIS is a necessary tool for Arizona to plan, analyze, model and manage our information," says James Meyer, Senior GIS Analyst, ADOT. "It has really helped us provide a visual array of information that allows our users to understand easily the complex environmental, economic and social issues. GIS is also useful as an effective tool for bringing people together on the same page when discussing programs and policies in the state."
The central objectives of MPD are to help identify current significant transportation issues in Arizona and to improve existing systems. MPD is also committed to cost effectively maintaining and expanding the state's transportation infrastructure. An ESRI GIS user for many years, the ADOT geographic information system and transportation section maintains the statewide street centerline GIS database and coordinates GIS issues for ADOT. Primarily focused on the more than 6200-mile state highway system, the section maintains the GIS database, also known as the Arizona Transportation Information System (ATIS Roads), and is the foundation for many planning studies and programs, including supporting the Federal Highway Performance Monitoring System (HPMS) for the state of Arizona.
ATIS Roads originated from the Accident Location Information Surveillance System (ALISS) map base that was maintained using photogrammetry and mapping until its conversion to GIS in the early 1990s. What began as a simple drawing tool has now grown into a full GIS.
One of the ongoing projects of ADOT is the ATIS Roads Update, which is the most important work of the group, since it is the basis for all the GIS data at the organization. This street centerline file for the state of Arizona is used to reference routes and mileposts that are geocoded to the Linear Referencing System and displayed on the maps. All data in ADOT uses the standard ATIS nomenclature for referencing location. See Figure 1.
Figure 1 Arizona's street centerline file is used against imagery in order to do a quick quality control on the entire Arizona Transportation Information System (ATIS), checking to ensure streets that exist in the real world are also captured in the system.
To assist in this update, ADOT adopted ArcGIS Image Server. "Using imagery, it is easy for us to identify areas where the streets in our database don't match up with real-world information," says Meyer.
Four terabytes of imagery are used to verify ground data. Once an ominous task for the department, today using this much raster data is an efficient means of viewing and analyzing its information. "Before ArcGIS Image Server, looking at images of the road network meant hooking up an extra hard drive and sifting through 8,000 tiles," says Meyer. "Using Image Server, we are able to view one continuous image quickly throughout the department on our network."
This usage is possible because of ArcGIS Image Server mosaics and because it processes imagery on the fly, providing users with the seamless image products they need without having to save multiple copies of the same image or perform time-consuming image pre-processing. ADOT is able to let users throughout the planning department access the most current imagery available. "This has taken out any reason to have data redundancy throughout the agency," says Meyer. "It also means we save money by not having to deal with extra storage requirements."
Many users at ADOT are new to GIS, so they are unfamiliar with the traditional means of loading and looking at images. "ArcGIS Image Server makes it easy for non-GIS users to view data in the way they are used to—quickly and intuitively. They don't think twice about the amount of data they are viewing or how quickly they can access it. This has helped us to support many more users than previously and to expand the use of GIS data throughout the whole organization," says Meyer.
MPD's goal is that ArcGIS Image Server will be adopted by other non-GIS departments such as the CAD Department. Potentially, CAD users will be able to perform quality assurance/quality control (QA/QC) on their survey data and measure the ground truth with the images. "We are hoping that ArcGIS Image Server will support all of ADOT's aerial image needs," says Meyer.
ArcGIS Image Server is also important in supporting the continuing efforts of the Highway Performance Monitoring System (HPMS) submittals. A requirement of each state, the HPMS is America's national database of highway information. Roadway extent, use, condition, and performance data are collected by and for the states and submitted to the Federal Highway Administration (FHWA) each year. See Figure 2. From a national perspective, the FHWA's primary intent with this program is to provide Congress with a policy tool for major highway legislation and funding decisions.
Figure 2 Image Server allows Arizona DOT to view 620 miles worth of state highway system and background imagery quickly and seamlessly.
ArcGIS Image Server is an integral tool that allows ADOT to continue to provide the best administrative, financial, and clerical support possible. The software has proven valuable for planning, traffic, and feature inventory, and the agency plans to continue expanding its use to more departments.
"The value of imagery is highest when a large number of users have access to the data quickly," says Clark Coffey, ArcGIS Image Server Product Marketing Manager. "With conventional solutions, image processing and distribution are difficult and time-consuming, and end users have difficulty accessing and using the imagery in their standard applications. ArcGIS Image Server is one component to the image solution, providing a new approach to storing, managing, processing, and distributing geo-imagery."
A company whose staff understand this well is Sanborn (Colorado Springs, Colo.). Sanborn first became known back in 1866 through its finely detailed fire insurance maps—maps so well created that they are actually still used today. Now part of the DMG Information Group of companies, which is owned by the United Kingdom-based Daily Mail and General Trust, Sanborn continues to provide geospatial solutions to its clients. Government agencies and companies in environmental management, national mapping, utility, and energy markets rely on them for their mapping needs.
Sanborn was the first commercial mapping firm to develop and implement a system for producing digital orthophoto imagery without distortion. Sanborn's images include surrounding streets and other cultural features that are not ordinarily visible in standard orthophotos, using a method they developed called Method for the Elimination of Terrain and Relief Displacement in Orthophotography (METRO).
This type of imagery is being used by a significant number of GIS users as a useful database layer for topographic, planimetric or cadastral mapping, utility data capture and accurate project analysis and design implementations. These images are created as both second-generation imagery for clients requiring geo-referencing to their original GIS data, and as first-generation orthophotos of the highest accuracy.
Many of Sanborn's imagery projects cover large areas with many customer stakeholders. Customers include large counties such as Maricopa County, Arizona, as well as councils of government and statewide initiatives. The average delivery range of imagery projects' size is 144 Gigabytes for one area to 4.4 Terabytes for up to 30 delivery areas, based on an average tile size of 2000' x 3000' for a delivery area size of 2000 tiles—the equivalent of 400 square miles. Sanborn's delivery format is RGB with a six-inch pixel size. Processing hundreds of terabytes of orthophotos per month for customers like these required Sanborn to find an innovative solution for clients who need massive amounts of imagery for their applications without extensive preprocessing or alteration of source data.
Sanborn chose ArcGIS Image Server because it provides rapid access to large quantities of file-based imagery, and the ability to process on the fly and on demand. The specialties of the two companies led Sanborn to become an ESRI implementation partner. "Image Server allows Sanborn to offer our clients a solution that gives them the images they require immediately and with consistency," says John Copple, chief executive officer of Sanborn.
Sanborn uses ArcGIS Image Server to diminish the interval between the collection of an image and its availability to users. Traditionally, image processing and distribution have been considered two separate stages in image utilization. Imagery was first processed and mosaicked into a large dataset, then put on servers for dissemination.
This separation has caused many problems: long preprocessing and loading times and data redundancy that exacerbates data storage issues and hinders efficient data management. With ArcGIS Image Server, these two stages are combined into one. The data received from an imagery supplier can be directly served. This ability enables administrators to maintain the primary imagery, while creating multiple specialized products on the fly when required. This is a significant and unique paradigm shift in how imagery is managed, processed, and distributed.
Using ArcGIS Image Server, Sanborn created Sanborn Quality Assurance (QA), a client imagery interface that facilitates Web-based quality checking of Sanborn-created orthophoto imagery products. Clients can view imagery through a standard Web browser as the image is being processed and add digital ‘issue points' to areas within the imagery that they feel may require attention. This real-time error reporting while Sanborn is processing the imagery makes data management much more simplified and reduces data redundancy and the delay in making the imagery accessible.
Clients can review orthoimagery as soon as they are available on Sanborn computer systems. Users are granted entry to the image Web application via secure login privileges to access a particular project. Clients may add QA flags to the project to indicate items requiring additional review, and these become immediately available inside the main GIS for viewing by Sanborn's production staff. There they are immediately available for technicians to review and resolve. These digital issue points give clients the ability to describe errors efficiently, and in turn, users are able to make fast, responsive changes such as color balancing and edgematching to the imagery. There is also a reporting tool to give up to the minute quality control status of the project. This tool makes the problem resolution process more streamlined and problem-free.
All imagery is served from a central image server to the client-side computer within a mapping interface in a standard Web browser format. ArcGIS Server 9.2 authors map documents that contain the image server data and QA/QC features classes. ArcSDE technology provides access to the data. Using this solution, the QA/QC points are immediately ready for status and resolution, and updates to the points by the QA team are immediately available online.
Built on fully scalable enterprise client/server architecture, ArcGIS Image Server offers multiplatform GIS/CAD/Web client access and direct access to many file formats and compression. Using the software, multiple imagery projects can be created from a single source.
Client visibility is granted into project management with macro-level access using a log-in access control with granular security role assignment. A custom ASP.Net application adds robust security. Resource assignments are now very easy and flexible. Users of the system log in online using a standard Web-based browser to access their projects.
Once logged in, the QA users are shown a list of projects they are able to access. By clicking a link from a pull-down menu called ‘Map,' the users open the QA environment for their projects. The initial map that is displayed shows the individual project status through colored pixels, green specifying tiles available for review, red for areas not yet available. The user of that project can then add and view the current issue points for the project.
Sanborn prototyped the system with customers from Colorado and Texas. Based on their positive prototype experience and customer feedback, the company is releasing a next-generation system for use by Maricopa County, Arizona. This county is approximately 9200 square miles, with an expected data delivery size of around 4.4 terabytes. See Figures 3-5.
Implementing the system took approximately 150 man hours from the initial design, including determining requirements, purchasing and implementing the software, customizing, testing and, finally, releasing the system. Sanborn QA requires nothing more than a standard Web browser and high-speed Internet connection. After clients utilize the system and are satisfied with the quality of the imagery, the project is delivered through either turnkey ESRI Image Server delivery, on demand data staging for after flight review, traditional hard drive or DVD delivery.
Says Copple: "The instant online imagery review accelerates our quality assurance and quality control review. We have given our customers the option to completely eliminate physical shipping requirements for QC purposes." Sanborn has also found they have successfully reduced their clients' IT involvement and provided for a secure solution for project management. Using this solution, Sanborn clients get fast image access optimized to their requirements with improved image quality and image metadata. By serving data to their clients directly, Sanborn has realized an overall production–to-delivery time decrease of approximately 66% in some cases.
Due to the schedule savings and the increased QC accuracy, Sanborn is able to improve its responsiveness while saving the customer costly edit and deliverable delays. "It's now easier for us as a company to assign our resources and offer flexible, efficient delivery options to our clients," explains Melinda Brown, Vice President of Corporate Marketing at Sanborn.
by Karen Richardson, Writer, ESRI, Redlands, Calif., www.esri.com/imageserver