Computer Environments for GIS and CAD
In the last few decades, computing environments have evolved to accommodate the need for integrating the separate, and often incompatible, processes of Geographic Information Systems (GIS) and Computer Assisted Design (CAD). This chapter will explore the evolution of GIS and CAD computing environments-from desktop to Web, and finally to wireless-along with the industry requirements that prompted these changes.
Before the 1980s, Computer Assisted Design (CAD) and Geographic Information Systems (GIS) functions were performed primarily on minicomputers running 32-bit operating systems such as VAX, VMS, or UNIX. Since minicomputers were expensive (approximately $200,000), many CAD and GIS solutions were bundled with hardware and offered as turnkey solutions. Although the combination of software and hardware was a popular option, it was still prohibitively expensive for small organizations, making CAD and GIS affordable only for government, academic institutions, and major corporations.
With the advent of the personal computer, particularly the IBM PC in 1981, which sold for approximately $1600, GIS and CAD became affordable for small- and medium-sized organizations.
Soon after the introduction of affordable personal computers, Autodesk developed the first PC-based CAD software, AutoCAD®;, which sold for approximately $1000. Desktop GIS products appeared on the market shortly thereafter. Rather than being retrofitted from minicomputer programs, the most successful of these applications were engineered specifically for the PC. With the availability of these powerful desktop programs, small- to medium-sized organizations that had previously relied on analog mapping and drafting had access to the wealth of information and time-saving tools formerly available only to large organizations.
CAD and GIS During the Workstation Phase
Although both GIS and CAD were introduced on the PC at around the same time, they were considered completely separate, and often incompatible, applications, making data sharing difficult. For example, precision and accuracy in GIS, unlike that of CAD, is variable, depending on scale. In CAD, precision was represented as 64-bit units (double precision), and in GIS as 32-bit units (single precision). Positional accuracy, which indicates the proximity of a feature on a map to its real location on earth, is quite high for CAD relative to GIS. For example, a 1:10,000 scale map might have a positional accuracy of 2.5 m (8.2 ft).
Another barrier to data sharing between CAD and GIS on the PC was the process of data collection. Many GIS survey instruments, such as Total Stations and GPS, collect data in ground units, rather than grid units. Ground units, which represent features on the earth’s surface exactly, are both longer and bigger than grid units. In addition, elevations and scale are not factored into ground units.
Since a great deal of map data was collected in the field, maps drawn in CAD were stored in ground units, and scale and coordinate systems were added afterwards. CAD engineers found that using ground units, rather than grid units, was advantageous. For example, assuming that dimensions on the map were accurate, if the line on the map measured 100 m (328 ft), it corresponded to 100 m on the ground. With GIS grid units, 100 m on the map might actually correspond to 100.1 m (328 ft 3 in) on the ground.
Another significant difference between CAD and GIS applications is that in CAD, unlike in GIS, points and polylines represent objects in the real world, but contain no attached information. In GIS, points, polylines, and polygons can represent wells, roads, and parcels, and include attached tables of information. In many cases, when spatial information was transferred from CAD to GIS applications, features were “unintelligent” and had to be assigned meaningful information, such as topology and attributes, manually. Because of this manual step, translation from CAD to GIS was extremely difficult, even with automated import tools.
GIS and CAD applications also provided different types of tools, making it difficult for users to switch systems. In GIS applications, tools were designed for data cleanup, spatial analysis, and map production, whereas tools in CAD were intended for data entry, drafting, and design. Since CAD drafting tools were much easier to use, CAD technicians were wary of using GIS software for creation of design drawings.
CAD drawings themselves also made it difficult to transfer data to GIS. A typical CAD drawing contains objects made up of arcs and arbitrarily placed label text. However, in GIS, text can be generated based on attributes or database values, often producing a result that is not aesthetically pleasing to a cartographer.
The representation of land parcels, common in GIS applications for municipalities, presented another challenge for integrating CAD drawings and GIS. Polylines portraying lot and block lines in a survey plan need to be translated into meaningful polygons in GIS that represent the parcel. Cleanup tools are used to ensure the accuracy of the lot and block lines. Each parcel must also be associated with its appropriate attributes, and a polygon topology must be created so that Parcel Identification Numbers (PINs or PIDs) inside each polygon are linked to the parcel database.
These barriers to integrating GIS and CAD led to the development of software solutions in each phase of the technological advancement in computing environments.
Bridging the Gap Between CAD in GIS in the Workstation Phase
In the initial workstation phase, the only way to integrate GIS data with AutoCAD data was to use DXFTM (drawing exchange format). This process was extremely time-consuming and error-prone. Many CAD drawings were drawn for a particular project or plan and never used again. Often these drawings were not in the same coordinate system as the GIS and had to be transformed on import. Even today, a GIS enterprise is built and maintained by importing data from CAD drawings. Graphic representations of layers of a formation, such as water, sewer, roads and parcels, are imported into the GIS using the file-based method.
To better merge the CAD world with the GIS world, a partnership was formed between Autodesk, Inc. and ESRI, leading to the creation of ArcCAD®;. ArcCAD was built on AutoCAD and enabled users to create GIS layers and to convert GIS layers into CAD objects. This tool also facilitated data cleanup and the attachment of attributes. Because ArcCAD enabled GIS data to be shared with a greater number of people, the data itself became more valuable.
Although ArcCAD solved some of the integration problems between CAD and GIS, it still did not provide full GIS or CAD functionality. For example, overlay analysis still had to be performed in ArcInfo®; and arcs and splines were not available in the themes created by ArcCAD.
In order to provide a fully functional GIS built on the AutoCAD platform, Autodesk developed AutoCAD Map®; (now called Autodesk Map®;), which made it simple for a CAD designer to integrate with external databases, build topology, perform spatial analysis, and utilize data cleaning, without file translation or lost data. In AutoCAD Map, lines and polygons were topologically intelligent with regard to abstract properties such as contiguity and adjacency. Since DWGTM files were already file-based packets of information, they became GIS-friendly when assigned topology and connected to databases. Precision was enforced instantly, since the DWG files could now store coordinate systems and perform projections and transformations. AutoCAD Map represented the first time a holistic CAD and GIS product was available for the PC Workstation environment.
Although AutoCAD Map could import and export the standard GIS file types (circa 1995: ESRI SHP, ESRI Coverage, ESRI E00, Microstation DGN, MapInfo MID/MIF, Atlas BNA) users began to request real-time editing of layers from third-party GIS files. To meet this demand, Autodesk created a new desktop GIS/CAD product called Autodesk World®;. World was designed for users who were not GIS professionals or AutoCAD engineers, and offered the basic tools of both systems: precision drafting and the capability to query large geospatial data and perform rudimentary analysis and reports.
World used a Microsoft Office interface to access and integrate different data types, including geographic, database, raster, spreadsheet, and images, and supported Autodesk DWG as a native file format, increasing the value of maps created in AutoCAD and AutoCAD Map. World enabled users to open disparate GIS data files simultaneously and perform analysis regardless of file type. Autodesk World could access, analyze, edit and save data in all the standard formats without import or export.
Although Autodesk World represented a real breakthrough in integrating GIS and CAD files, it lacked an extensive CAD design environment. AutoCAD was still the CAD environment of choice, and AutoCAD Map continued to offer better integration of GIS within a full CAD environment. Autodesk World filled a need, much like other desktop GIS solutions at the time, but there was still a gap between the CAD design process and analysis and mapping within the GIS environment.
In the same time period, AutoCAD Map continued to evolve its GIS capabilities for directly connecting, analyzing, displaying, and theming existing GIS data (in SDE, SHP, DGN, DEM, and Raster formats, for example) without import or export. In support of the Open GIS data standard, AutoCAD Map could read OpenGIS information natively. GIS and CAD integration continues to be one of key features of AutoCAD Map.
CAD and GIS During the Web Phase
The next significant inflection point in technology was the World Wide Web, which increased the number of users of spatial data by an order of magnitude. With the advent of this new technology and communication environment, more people had access to information than ever before.
Initially, CAD and GIS software vendors responded to the development of the Web by Web-enabling existing PC applications. These Web-enabled applications offered the ability to assign Universal Resource Locators (URLs) to graphic objects or geographic features, such as points, lines and polygons, and enabled users to publish their content for viewing in a browser as an HTML (Hypertext Markup Language) page and a series of images representing maps or design.
Software developers also Web-enabled CAD and GIS software by providing a thin client or browser plug-in, which offered rich functionality similar to the original application.
CAD for the Web
In the early Web era, slow data transfer rates required thin clients and plug-ins to be small (less than one megabyte) and powerful enough to provide tools such as pan and zoom. In light of this, Autodesk’s developed a CAD plug-in called Whip! which was based on AutoCAD’s ADI video driver.
Although the Whip! viewer today has evolved into the Autodesk DWFTM Viewer, the file format, DWF (Design Web Format) remains the same. DWF files can be created with any AutoCAD based product, including AutoCAD Map, and the DWF format displays the map or design on the Web as it appears on paper. DWF files are usually much smaller than the original DWGs, speeding their transfer across the Web. With the development of DWF, Internet users had access to terabytes of information previously available only in DWG format. This was a milestone in information access.
From a GIS perspective, 2D DWF files were useful strictly for design and did not represent true coordinate systems or offer GIS functionality. Although Whip!-based DWF was extremely effective for publishing digital versions of maps and designs, GIS required a more comprehensive solution.
Note: Today, DWF is a 3D format that supports coordinate systems and object attributes.
GIS for the Web
As the Web era progressed, it became clear that a simple retrofit of existing applications would not be sufficient for Web-enabled GIS. In 1996, Autodesk purchased MapGuide®;from Argus Technologies. MapGuide viewer was a browser plug-in that could display full vector-format GIS data streamed from an enormous repository using very little bandwidth. Each layer in MapGuide viewer could render streamed data from different MapGuide Servers around the Internet. For example, road layers could be streamed directly from a server in Washington, DC, while the real-time location of cars could be streamed directly from a server in Dallas, Texas. MapGuide managed its performance primarily with scale-dependent authoring techniques that limited the amount of data based on the current scale of the client map.
MapGuide could perform basic GIS functions such as buffer and selection analysis, as well as address-matching navigation with zoom-goto. One of the more powerful aspects of MapGuide was the generic reporting functionality, in which MapGuide could send a series of unique IDs of selected objects to any generic Web page for reporting. Parcels, for example, could be selected in the viewer and the Parcel IDs could be sent to a server at City Hall that had the assessment values. A report was returned, as a Web page, containing all the information about the selected parcels. Again, the report could reside on any server, anywhere. The maps in MapGuide were just stylized pointers to all the potential servers around the Internet, containing spatial and attribute data. MapGuide was revolutionary at the time, and represented, in the true sense, applications taking advantage of the distributed network called the Web.
MapGuide continued to evolve, using ActiveX controls for Microsoft Internet Explorer, a plug-in for Netscape and a Java applet that could run on any Java-enabled browser. Initially, MapGuide used only its own file format, SDF, for geographic features. Later, MapGuide could natively support DWG, DWF, SHP, Oracle Spatial, and ArcSDE.
Although MapGuide was an extremely effective solution, it could run only on Microsoft Windows servers. The development of MapGuide OpenSource and Autodesk MapGuide Enterprise was inspired by the need to move toward a neutral server architecture and plug-in-free client experience. MapGuide could be now be used either without a plug-in or with the newest DWF Viewer as a thin client.
Within AutoCAD Map, users could now publish directly to the MapGuide Server and maintain the data dynamically, further closing the GIS-CAD gap.
CAD and GIS During the Wireless Phase
Wireless CAD and GIS marked the beginning of the next inflection point on the information technology curve, presenting a new challenge for GIS and CAD integration. Since early wireless Internet connection speeds were quite slow-approximately one quarter of wired LAN speed-Autodesk initially decided that the best method for delivering data to handheld device was “sync and go,” which required physically connecting a handheld to a PC and using synchronization software to transfer map and attribute data to the device. GIS consumers could view this data on their mobile devices in the field without being connected to a server or desktop computer. Since handheld devices were much less expensive than PCs, mobile CAD and GIS further increased the number of people who had access to geospatial information.
Autodesk OnSite View (circa 2000) allowed users to transfer a DWG file to Palm-OS handheld and view it on the device. When synchronized, the DWG file was converted to an OnSite Design file (OSD), and when viewed, allowed users to pan, zoom and select features on the screen.
With the advent of Windows CE support, OnSite View allowed redlining, enabling users to mark up a design without modifying the original. Redlines were saved as XML (Extensible Markup Language) files on the handheld and were transferred to the PC on the next synchronization or docking. These redline files could be imported into AutoCAD, where modifications to the design could be made.
Autodesk OnSite View could be considered more mobile than wireless, since no direct access to the data was available without connecting the mobile device to the PC. OnSite View filled a temporary niche before broadband wireless connections became available.
Wireless GIS and Location-Based Services
Initially, the mobile GIS solution at Autodesk was OnSite Enterprise, which leveraged the mobility of OnSite and the dynamism of MapGuide. OnSite Enterprise created handheld MapGuide maps in the form of OSD files that users could simply copy off the network and view on their mobile devices with OnSite.
In 2001, when true broadband wireless came on the horizon, Autodesk created a new corporate division focused solely on Location-Based Services (LBS). The burgeoning Wireless Web required a new type of software, designed specifically to meet the high transaction volume, performance (+ 40 transactions per second), and privacy requirements of wireless network operators (WNOs). The next technological inflection point had arrived, where maps and location-based services were developed for mass-market mobile phones and handheld devices.
Autodesk Location Services created LocationLogicTM, a middleware platform that provides infrastructure, application services, content provisioning, and integration services for deploying and maintaining location-based services. The LocationLogic platform was built by the same strong technical leadership and experienced subject matter experts that worked on the first Autodesk GIS products. The initial version of LocationLogic was a core Geoserver specifically targeted for wireless and telecom operators that required scalability and high-volume transaction throughput without performance degradation.
Point of Interest (POI) queries
Geocoding and reverse geocoding
Integrated user profile and location triggers
Points of Interest (POIs) usually comprise a set of businesses that are arranged in different categories. POI directories, which can include hundreds of categories, are similar to Telecom Yellow Pages, but with added location intelligence. Common POI categories include Gas Stations, Hotels, Restaurants, and ATMs, and can be customized for each customer. Each listing in the POI tables is spatially indexed so users can search for relevant information based on a given area or the mobile user’s current location.
Geocoding refers to the representation of a feature’s location or address in coordinates (x,y) so that it can be indexed spatially, enabling proximity and POI searches within a given area. Reverse geocoding converts x, y coordinates to a valid street address. This capability allows the address of a mobile user to be displayed once their phone has been located via GPS or cell tower triangulation. Applications such as “Where am I?” and friend or family finders utilize reverse geocoding.
Route planning finds the best route between two or more geographical locations. Users can specify route preferences, such as shortest path based on distance, fastest path based on speed limits, and routes that avoid highways, bridges, tollways, and so on. Other attributes of route planning include modes of transportation (such as walking, subway, car), which are useful for European and Asian countries.
The maps produced by the LocationLogic’s Geoserver are actually authored in Autodesk MapGuide. Although the Geoserver was built “from the ground up,” LocationLogic was able to take advantage of MapGuide’s effective mapping software.
LocationLogic also supports user profiles for storing favorite routes or POIs. Early versions of LocationLogic also allowed applications to trigger notifications if the mobile user came close to a restaurant or any other point of interest. This capability is now used for location-based advertising, child zone notifications, and so on.
Early LBS applications built on LocationLogic included traffic alerts and friend finder utilities. For example, Verizon Wireless subscribers could receive TXT alerts about traffic conditions at certain times of day and on their preferred routes. Friend finder utilities alerted the phone user that people on their list of friends were within a certain distance of the phone.
More recently, Autodesk Location Services has offered two applications built on LocationLogic that can be accessed on the cell phone and via a Web browser: Autodesk InsightTM and Autodesk Family Minder.
Autodesk Insight is a service that enables any business with a PC and Web browser to track and manage field workers who carry mobile phones. Unlike traditional fleet tracking services, Insight requires no special investment in GPS hardware. Managers and dispatchers can view the locations of their staff, determine the resource closest to a customer site or job request, and generate turn-by-turn travel instructions from the Web interface. Managers can also receive alerts when a worker arrives at a given location or enters or leaves a particular zone. Reports on travel, route histories, and communications for groups or individuals, over the last 12 or more months, can be generated from the Web interface.
Family Minder allows parents and guardians to view the real-time location of family members from a Web interface or their handset. Parents and guardians can also receive notifications indicating that a family member has arrived at or left a location. The recent advances in mobile phone technology, such as sharper displays, increased battery life and strong processing power, make it possible for users to view attractive map displays on regular handsets.
Enterprise GIS: Workstation, Web and Wireless Synergy
In 1999, Autodesk acquired VISION*®;, along with its expertise in Oracle and enterprise GIS integration. This was a turning point for Autodesk GIS. File-based storage of information (such as DWG) was replaced with enterprise database storage of spatial data. Currently, Autodesk has integrated VISION* into its development, as seen in Autodesk GIS Design server. Autodesk TopobaseTM, which also stores its data in Oracle, connects to AutoCAD Map and MapGuide to provide enterprise GIS Public Works and Municipal solutions.
MapGuide and AutoCAD Map support Oracle Spatial and Locator, which allow all spatial data to be stored in a central repository. All applications can view the data without duplication and reliance on file conversion. AutoCAD Map users can query as-built information from the central repository for help in designs, and any modifications are saved and passed to GIS users. The central GIS database can also be published and modified from Web-based interfaces, such as MapGuide. Real-time wireless applications, such as Autodesk Insight, can use the repository for routing and mobile resource management.
Autodesk has a history of leveraging inflection points along the computing and communication technology curve to create exciting and innovative solutions. For over two decades, Autodesk’s mission has been to spearhead the “democratization of technology” by dramatically increasing the accessibility of heretofore complex and expensive software. This philosophy has been pervasive in the GIS and LBS solutions that it has brought to a rapidly growing geospatial user community.
The next potential inflection point will emerge with the development of Service Oriented Architecture (SOA), built upon a Web 2.0 and Telco 2.0 framework. Not only will the distributed data and application architecture continue to increase the number of geospatial data consumers, but it will increase the use and accessibility of powerful analytical and visual tools as well.
CAD and GIS will soon be so integrated that the location on the timeline from design to physical feature or survey to map will be the only way to determine which technology is currently being used. Seamless and transparent services and data distribution will bring subsets of CAD and GIS utilities together to produce dynamic applications on demand. Servers will no longer host only databases, but will run self-supported applications, functions, and methods that are CAD, GIS, database, and business oriented. These services will be offered through the new Web 2.0 to provide powerful solutions.
Transparent GIS Services and integrated geospatial data will affect a larger segment of the population. No longer will the technology just be “cool,” but will be completely integral to daily life. Autodesk’s role will be to continue to provide tools that will leverage this new reality and meet the coming new demands in information and technology.
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