Once a fairly straightforward issue, data storage and retrieval has become multifaceted and complex. Simply fattening the pipeline and adding disk space doesn’t do the job anymore. Volumes of virtually unlimited data accumulating from high-resolution image acquisition and continuous cartographic map creation and maintenance, combined with a broad range of platform scenarios and bandwidth requirements for viewing and transmission, far exceed the limited capabilities of a traditional infrastructure. In addition, the need to support customization, the desire for compliance with emerging format standards and serving protocols, and the increasing use of the Web to deliver data underscore the need for an integrated, enterprise-class storage and distribution option specifically designed for geospatial image data.

The Institut Cartogràfic de Catalunya (ICC)—Cartographic Institute of Catalonia—is taking steps to address this complex issue. ICC is the mapping agency of the Generalitat de Catalunya, the government of the region of Catalonia in northeast Spain. The region includes Barcelona, Catalonia’s capital. The institute’s mandate is to produce and distribute cartographic and geologic information, including Earth imagery, to public and private institutions.

A Growing Library
In addition to maintaining a huge on-site paper map library, ICC maintains a vast library of digital data, including source data from the Servei Geològic de Catalunya (Geological Survey of Catalonia). Historically, maps and imagery have been delivered by ICC on physical media or made available for download via an ICC-maintained FTP site. In 2004, the institute served more than 11,000 registered users with more than 215,000 downloads, each averaging 8MB. In addition, 300,000 image tiles totaling more than 14TB were delivered to end users on more than 4,000 CDs and DVDs. Whether delivered on disc or via FTP, the data were only available in their entirety, not as user-defined areas of interest. Once delivered, the data had to be stored and maintained by the end user.

“(ICC) had been distributing these digital materials to customers on an individual basis for quite some time,” says Lluis Colomer, ICC’s general technical sub-director. “These methods became impractical as our catalog and user base grew. It was clear that our future involved serving digital imagery directly to public and private institutions, as well as to individual users, via the Web.”
 

Efficient Delivery and Integrated Web Access
One of ICC’s challenges is the dual nature of its mission. The institute must accommodate the needs of the global “front-end” user—e.g., the tourist planning a trip to Catalonia’s capital, Barcelona—as well as the needs of local Catalonian businesses and  public agencies.

On the front end, the system must handle thousands of simultaneous requests for gigabytes of user-defined areas of interest through standard Web browser interfaces. ICC initially began fulfilling requests by serving tiled
mosaics—each area of interest following tile boundaries—but the institute’s staff would have preferred to clip out and serve partial tiles, then quickly render the custom scene using the local browser.

The back-end challenge is to provide businesses and public agencies in Spain with integrated access to the ICC database through various third-party geographic information system (GIS) applications operated at the client and/or server level. ICC hoped to achieve this by using Web Map Services (WMS), a set of standard interfaces defined by the Open Geospatial Consortium (OGC) for transmitting map data.

An Integrated Solution
ICC has been leveraging LizardTech’s MrSID wavelet technology for its digital orthophotos and topographic base imagery for years to reduce capacity requirements and associated storage costs. The institute turned to LizardTech again when it needed to develop an Internet-based distribution solution.

ICC is implementing LizardTech’s ExpressServer technology to serve high-resolution images across the Web to hundreds of thousands of users. ExpressServer is a server add-on that optimizes the transmission and viewing of images in MrSID, JPEG 2000, TIFF, JPEG, PDF, DjVu and other formats with or without a browser plug-in. Higher throughput was a key driver for the decision, but ICC also was attracted to ExpressServer’s inter-operability with OGC WMS publishing.
 

Through an online interface, individuals may now select maps by area, type and scale—e.g., a topographic view of Barcelona at 1:5,000—for instant viewing and quick download. The WMS API provides access to the ICC geodatabase for professionals, businesses and agencies, and the institute’s implementation is faster at building the spatial index and serving images than the main server alone. Specifically, the new approach offers the following key benefits to ICC and its diverse user base:

Positive user experience: High-speed delivery of high-resolution image data allows ICC to effectively provide instant online viewing of stunning imagery even under the load of thousands of simultaneous image requests.

Reduced capital expenses: ICC’s material and labor costs associated with burning and shipping CDs and DVDs have been eliminated, and the institute has been able to leverage its existing data and system infrastructure investment.
Increased image data value: Interoperability with OGC WMS publishing protocol allows the ICC data to be integrated with WMS-compliant geospatial data stores anywhere in the world. As a result, ICC’s data can be included in other search applications, thus increasing the data’s usefulness.

Productivity gains: By using the WMS API, finished projects can be delivered to requesting agencies and businesses as a data stream. Furthermore, without the need to burn CDs or DVDs, the time between completing a project and getting map and image data in the hands of a client has been reduced from days or weeks to just hours.

Support for common platforms: Leading third-party GIS and image processing packages support LizardTech technology, and free plug-ins and viewers are available for Windows, Macintosh, Sun/Solaris, Linux, various Unix systems and WinCE.

“We found that ExpressServer was the fastest and most efficient way to deliver our map data to our users,” says Colomer. “ExpressServer significantly increases the efficiency of our image distribution and has allowed us to build into our system other features our users were requesting.”

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