Building a system to disseminate digital map and geospatial data online.

ABSTRACT

The expectation of library patrons to get all of the information they need, including geographic information, accessible on their desktops has created challenges to map and Geographic Information System (GIS) libraries. This new expectation has forced libraries to think about how to design a system that will allow diverse geographical information to be available over the Internet. Some libraries have built a site to distribute localized data, others have developed a system to make only maps accessible online. Princeton University Library's Digital Map and Geospatial Information Center started a pilot map scanning project in early 2004 to build a system, to develop specifications for scanning maps and compressing TIFF images to JPEG2000 file format, and to establish workflows. The system was built using many off-the-shelf commercial software packages. This article discusses challenges of building a system and explains how Princeton developed a scanning process and standards, workflows, and what lessons were learned in building such a system.

INTRODUCTION

Libraries purchase and receive geospatial data and paper maps free of charge through the Federal Depository Library Program (FDLP). One of the requirements of the FDLP is to make all the materials distributed through it freely accessible to the public. Because of this requirement and demands from library users to make all the materials accessible on their desktops, many libraries scan their paper maps and make them accessible online. However, one major problem libraries face is how to design a system that will allow the user to search, view, and download diverse geospatial data and digital maps. This article examines the challenges of creating such a system and explains how Princeton University Library's Digital Map and Geospatial Information Center has designed a system that will allow the library to integrate various forms of geographic information and make them accessible online from one interface.

CHALLENGES

There are numerous challenges in making geospatial data and digital maps accessible over the Internet. Many libraries have used ESRI's ArcIMS and ArcSDE, and relational databases such as Micosoft's SQL Server, Oracle, etc., but they were not very successful in making diverse collections of digital maps and geospatial data accessible online from one interface. This was due to the following reasons:

* Disseminating digital maps and geospatial data via ArcIMS technology is not practical for libraries when they have a great quantity of material covering different parts of the world at different scales and in different formats.

* There is no simple way to view and download vector geospatial data stored in ArcSDE without creating ArcIMS image or feature services. Using ArcIMS to build image and feature services to view and download vector data is not only time consuming but also uses a lot of processing power on a server.

* Many libraries are scanning large historical maps and aerial photographs. Some of them are georeferenced but many are not. Disseminating these types of materials with vector geospatial data is a real challenge.

* The file sizes of scanned maps and geospatial data could vary from a few megabytes to a gigabyte. Making a large file accessible over the Internet is a challenge.

* Designing a system that has easy workflows and ease of maintenance is difficult.

Because of these reasons, I spent a few years testing different server side technologies to build a system that will not only allow our library to organize and manage digital maps and geospatial data with…