The Many Layers of Tasmania
May 28, 2009
All images courtesy of TASMAP.
When tourists and locals pull on their hiking boots to trek through Tasmania’s picturesque landscape, they often take a trusty companion along to guide them--a topographic map created by TASMAP, the Tasmanian government agency responsible for supplying accurate, up-to-date maps describing the mountain peaks, caves and beaches of Australia’s only island state. More than 40 percent of the state consists of national park and reserve land with 1,000 mountain peaks and more than 300 islands. Accurately mapping this diverse topography requires a combination of ground survey control, aerial photogrammetry and cartography.
The 1:25,000 map series is the most popular of TASMAP’s products and is used by government agencies, businesses and consumers. Produced since the 1970s, the map series provides 415 large-scale base maps for all of Tasmania and includes topographic information such as elevation, water bodies, and government landmarks along with property information.
Over four decades of mapmaking, TASMAP has witnessed significant changes in map production methods--including the introduction of GIS. Using ESRI’s ArcGIS suite of software, TASMAP now manages, creates and edits all necessary map layers digitally. “Before GIS, map production involved intricate manual processes with a single map sheet taking many people months to produce,” says Mark Chilcott, Spatial Operations, Geodata Services, Department of Primary Industry and Water. “Today, maps can be produced quickly and efficiently by automating many of the mundane tasks. This allows our cartographers to focus on cartography and reduces production time significantly.”
A Centralized Geodatabase
When digitizing daily mapmaking activities, TASMAP focused on building on past experiences to create solutions that would help guide them toward the future. “It was important [that] we didn’t reinvent the wheel,” Chilcott says. “While the specifications for creating maps are the same, the methods are obviously quite different. Cartography is not a dead art; it is very much a required skill.”
The process starts in the field. The Department of Primary Industries and Water employs a number of surveyors whose main roles are to establish and maintain the geodetic network and to ensure the quality of the cadastral parcel fabric. “This layer is shown on our maps, and the only way we can get it is to capture the information from the plans the surveyors submit to the Land Titles Office,” Chilcott explains. “As the quality assurance guardian of the cadastre, the Land Titles Office records the title and performs a number of checks to ensure that adjoining parcels are accurate.”
Each map requires aerial photogrammetry to capture additional specific data. These data are modeled into separate layers such as transportation, rivers (hydrography), vegetation, points of interest, contours, cadastre, etc., that comprise the spatial data infrastructure for the maps. “In the old days, this information was physically scribed onto plastic sheets, and a complex set of procedures was used to complete a map,” Chilcott says. Modern 3D computer modeling software has greatly simplified the process.
Advanced survey and photogrammetry techniques have reduced the amount of time needed for the data collection aspect of mapmaking. But the heart of TASMAP’s newfound efficiency is its ability to apply database-driven mapping with a geodatabase, which is a common data storage and management framework for ArcGIS. Since data from all ground and aerial surveys are stored in one location, they can be updated and edited with little error. Using the geodatabase also means that mapping attributes such as north arrows, map names and numbers, grid references and climate graphs can be created using intelligent information directly from the data themselves and stored with the map features.
All changes to these attributes are managed with an easy-to-use template TASMAP created using ArcGIS to simplify editing and reduce the potential for mistakes. The template contains the map frame and all marginal information required for each sheet. For example, grid references are created from a sample point that is unique for each map and stored in the geodatabase. Staff members can edit data for new points and precalculate the Universal Grid Reference. Climate graphs are created directly from climate data obtained from the Australian government’s Bureau of Meteorology. Map names, numbers, editions and dates as well as the cover and location box are now objects generated from code. While the initial setup took some effort, the end result is that each map margin and template takes less than one minute to generate. Mistakes and errors are greatly reduced, and a considerable amount of work is saved.
Taming the marginal data meant TASMAP could focus on streamlining the extraction and geoprocessing of the map data. This task is now performed on each editor’s desktop using a personal geodatabase with ArcGIS and FME software. Using FME to build graphic geoprocessing models automates data manipulation from a variety of sources. Using GIS to create new information by applying geoprocessing operations to existing data such as clip to boundary, making single layers into multiple layers, joining lookup tables, and rotating objects like waterfalls to rivers, gates to roads, and buildings to roads again saves TASMAP time and effort. “ArcGIS and FME have many powerful tools,” Chilcott says. “The software is easy to adjust to meet our needs, and most importantly, the users can retain ownership of their data.”
Digitally Managing Production
Another area of improvement TASMAP found through automating cartographic production was the placement of annotation on the map sheets. By digitally managing annotation, TASMAP has significantly reduced the time necessary to create each map. “Traditionally, ‘lettering the map’--the process of selecting the type, preparing the names and placing them in position--was considered among the more complex and time-consuming parts of the cartographic process,” Chilcott says. “While this is still one of the most time-consuming processes, it is now significantly less time consuming and considerably easier than in the past.”
Using ESRI’s Maplex extension to ArcGIS, annotation can now be created directly from the geodatabase. Maplex manages symbolization and annotation placement through user-defined rules based on map complexity. Annotation placement is prioritized according to sophisticated cartographic rules, and filters are set up to handle densely packed annotation in urban areas differently than filters for annotation in rural areas.
The last challenge TASMAP faced in their cartographic production work flow was printing. TASMAP produces maps using offset printing, sending maps in PDF files to the printers. The maps are created using standard CMYK (cyan, magenta, yellow and key black) color. “In the recent past, we would export the almost completed map to Adobe Illustrator for finishing to ensure the CMYK color separation for offset printing could be achieved,” Chilcott says. “Now we use ArcGIS for the entire mapping process--from data extraction, editing, finishing and the final export to PDF for printing. No other application needs to be used in the entire process.”
Even with these efficiencies, producing 415 maps is a large task that requires many resources. So TASMAP also uses GIS technology to more-effectively manage the work flow of when to produce maps for use and resale. “The question is always ‘Which map sheet do I work on?’” Chilcott says. Using ArcGIS, TASMAP has developed tools to assist in managing map production. For example, a feature class of the Map Extent tool is linked to the stock database to produce reports of real-time stock levels. ArcGIS Model Builder is used to create a weighted matrix to identify which maps should be worked on over the next 12 months. Stock levels for the coming year and the highest selling area are also predicted.
In the past, it took six months for up to four cartographers to produce a map. Today, it takes one cartographer two weeks to produce the same map to the same specifications with the same high-quality cartography. “Granted, in the past, the map-production process also included the data-capture process, which in itself was time consuming,” Chilcott says. “With today’s technology, the data sets come from our corporate and state spatial data infrastructure.”
Continued technology advances will likely streamline the process even further. For example, Chilcott notes that LiDAR might eventually replace photogrammetry as the aerial imaging method of choice. “With LiDAR, one can obtain better elevation models and, thus, contours, and much of the data capture can be done for mapping purposes with a single orthorectified image,” Chilcott says. “It is starting to be questioned if we need to capture data with the use of 3D photogrammetry models now.”
From the surveyor’s perspective, Chilcott says that “electronic lodgement” will likely play a key role. “Currently, the surveyor prints the survey to paper; the paper is submitted and then scanned; the scanned copy is redigitized; and so on and so forth. And when the next surveyor wants the data back, he or she gets the scanned image and has to redigitize the data,” he explains. “Having the ability to upload a survey-accurate plan of the parcels to the Land Titles Office, which should then be able to automatically do most of the checks and then include the new information in the current cadastral layer--this kind of digital upload and download of the data is the future.”
Such changes will allow tomorrow’s maps to be produced with even fewer resources and in even less time. The primary question then will become one of format. “If we can produce a map automatically from the most current data every year and make it available for download on the Internet for free in a format that is not cartographically finished (and thus much harder to ‘read’ or interpret), is this more important to the user than if we did a really great cartographic finished map with offset printing every 10 years and it cost $15?” Chilcott says. “To my mind, that is the debate people will need to have.”