Digital cartography is a mapmaking method, which uses analysis and processing functions as well as graphical devices in the computer to design and edit maps. It has taken the place of traditional hand making methods. Modern GIS software such as ArcGIS, ArcView, MapGIS, MapInfo, ERDAS, etc, and graphic design software such as AutoCAD, Adobe Illustrator and CorelDraw, all comes with built-in mapmaking tools. The toolsnormally include map vectorisation, data collection, data processing, data analysis, data updating, which will be followed by map editing and map output.
Living in a fast-paced society, it is essential to meet the market demands for quicker and more efficient service delivery. In order to improveworking efficiency, shorten working period and createcompetitive advantage, cartographic professionals and technicians are required to be familiar with different kinds of data processing and map-making software. They are also required to analyse the properties and advantages and develop the techniques appropriately.
Recently, Yunnan Province Mapping Institution has undertaken two big projects:Generalisation and Updating of Topographic Maps; and National Second Land Use Status Quo Investigation (rural area part). Both of them are heavy tasks and need to be completed in a short duration. Traditional mapping method will not be able to meet the deadlinesspecified in the contract. After analysing the whole project, the technicians adopted a series of new techniques and methods, solving many technical problems in the production process, improving work efficiency and creating better social and economic benefits.
Yunnan Province Map
(Courtesy of ChinaMaps.info)
Three new digital cartographic technologies were used in both projects. 1) Comprehensive Downsizing Computer Technology has very high efficiency (shorten production time by one-sixth in average) and produce much more reliable map quality, as compared to traditional map downsizing technology. 2) Space Database Engine (SDE) was used in the National Second Rural Land Use Status Quo Investigation providing quicker and more convenient data processing and database creation. 3) One-click Mapping Technology used in the image editing of this project, improved the efficiency of image editing. Each technology will be discussed in detail.
The application of Comprehensive Downsizing Computer Technology
The ever increasing resolution of satellite remotely sensed imageries and the evolving large-scale data downsizing tools (also known as Comprehensive Downsizing Computer Technology) contribute a lot to the modern geographic spatial databases. Comprehensive Downsizing Computer Technology extracts, downsizes and transforms the information from large scale data to update small scale data. Map downsizing is a universal method to create different sizes of maps. Manual map downsizing is slow and poor in accuracy, on the other hand, Comprehensive Downsizing Computer Technology is still a puzzle in the map-making world and lacks downsizing standard.
Gen Tools isapractical downsizing software developed by China Geographic Information Centre and Wuhan University. This software solvesthe problems involving time, energy and accuracy faced inmanualmap downsizing method. It integrates a series of algorithms and comprehensive models of practical topographic map downsizing from 1:10000to 1:50000 scales. It builds a workable comprehensive standard rule database and adopts Computer Geometry Triangulation Network and Thiessen polygon building for the calculation of distance, direction, topology, semantics among space targets to explore space conflict and neighbour targets as decision basisfor offering certain integrated quantification. It also set up a humanised service platform andimproves the updating efficiency for 1:50000 map downsizing.As a result, it has been widely used by many mapping production institutions.The software was used in the downsizing of 1:50000 topographic maps in 2007. It was found that although this software can downsize the map data better, it still cannot meet the requirement of building a database. Therefore, some related downsizing auxiliary tools were developed so as to solve the problems of data formatting and data processing quality during a batch convert. The task was completed semi-automatically through interactions between operators and computers.
Gen Tools interface
At the end of 2009, the institution undertook another project which downsized 216 topographic maps in the proportion of 1:50000 for land use updates in Yunnan Province. The team was given three to four months to complete the task. Considering the tight deadline, the team decided to improve the degree of automation in the map downsizing process. The technicians developed a series of tools for data processing focusing on land use comprehensive downsizing in ArcGIS. The land was batched using database of 30 counties, making sure each county processed datareliably and effectively in the same standard, also produced the maps quickly. These data processing tools include: automatic selection of land map pattern spot, automatic simplification of land boundary, automatic selection of align feature and road centreline. Based on the automatic processing, residential border and a few unreasonable land boundaries were fixed manually. This is a necessary process, especially in areas like Wenshan where rural residential are scattered. The task was accomplished in time with high quality with the help of proper technology application. The output was well-accepted through the inspection held by the second inspection office in Yunnan province.
The application of Spatial Database Engine technology (SDE)
Spatial Database Engine technology (SDE) is a server software, which can store, manage and retrieve spatial data quickly in the industrial standard management system. It adds spatial data into the expansion relationship database management system, offering efficient management, highly efficient operation and rogatory data ports to spatial and non-spatial data. SDE has some main characteristics: supporting large data sets, high performance extraction of spatial data, flexible high performance spatial data search, specialised for multi-user and distributed environment design, open structure system, logically seamless and continuous space target data model, two-stage submitted controls, supporting various hardware platform, strong and flexibleapplication development environment, complete flexibility on security control mechanism, and quick response for multi-user concurrent queries.
The Institute began to participate in the Second National Land Survey (Rural) Project in the second half of 2008.This project involved large amount of data with high data quality requirements to achieve timely andaccurate data collection, standard and unified data, succession of seamless data map, close topological relation, and accurate area summary requirements.Super Map SDX+ technology was adoptedto partition the data acquisition. With full use of the SDE multi-user concurrent function, data can be updated concurrently, saving a lot of time. The dataprocessing and storage was using ArcSDE technology. ArcSDE allowsfast data processing through easy establishment of topological relation;hence shorten the time for database establishment. At the same time,the application of SDE techniques allows faster data production, collection and inspection as errors can be eliminated in the production process.
The application of One-click Mapping technology
“One-click” automatic mapping is every cartographer’s dream. In recent years, GIS softwaredevelopers are competing to develop higher degree of automation in cartographicsoftware to reduce the mechanical labour manual repetition in cartography. Duringthe Second National Land Survey (Rural) Project, the Institute needed to produce nearly 1400 maps, such as current land use chart, basic farmland map, slope classification map of arable land, land survey clear draw, etc.Beijing Kanq Digital Surveying & Mapping provided the Institute with an application using “one-click” automatic mapping technology that can easily generate map by extracting information from the database.It can greatly reduce border trims process, data frame cutting, layer classification symbol rendering,and drawing process time. Producing related derivative maps are quite convenient too. The amount of drawing time throughout the project was less than 1 month, which is impossible to achieve using traditional mapping method.
“One-click” automatic mapping software interface
As IT, GIS and RS technology evolved, digital cartographic technology will be further enhanced. Map production will be quicker and more intelligent, while maps will become more attractive, diverse, and interactive. Cartographers will be free from heavy map editing work, and able to put more energy into map design and development instead.