Making Design Data GIS Ready

The Importance of Good Data

Until recently, the practice of GIS (Geographical Information Systems) gave little attention to issues that occurred by error, inaccuracy and the imprecision in geospatial datasets. However, today we are finding that as more professionals and organizations are relying on GIS for analysis related to infrastructure and engineering projects that the integrity of the data is paramount and many times can be the sole reason for the success or failure of a GIS project.

GIS has largely been used as an asset management solution by many organizations and relies heavily on being able to integrate data from several sources, one of which is engineering design information or CAD. This has been traditionally accomplished through the use of translation tools, or data exchange formats like the .DXF file, which has the potential to alter the underlying engineering precision while largely void of any descriptive detail needed by a GIS.

Consider the following example of a utility company tasked with creating reports as part of an audit in which the utility company is taxed based on the number of water pipes it has in operation. The engineering design is done in AutoCAD, needed for its precision and engineering based tools to create the data. The water pipe data is then exported to a .DXF file and then imported into a utility management application (GIS) where a report is done to determine how many feet of pipe exist in its network. If duplicates were in the original AutoCAD drawing and the GIS did not recognize these as errors, the utility company could in fact be charged twice for that pipe.

Cleaning Up Data

To overcome this obstacle AutoCAD Map 3D has the ability to identify errors at the data creation, or design phase of a project using what are called ‘drawing clean up’ tools. These can be run on any number of layers, isolated to certain areas in a drawing, or used to convert object types from one type of AutoCAD feature to another (i.e. lines to polylines, arcs to circles). However, the most important part of drawing cleanup is its ability to find and fix the eleven top errors found in design information.
 

Drawing cleanup helps organizations that are either designing information internally, or are also getting information from third-parties like contractors and consultants ‘clean’ the geographic data before it is migrated into a GIS. It should be acknowledged that most GIS software has tools that will clean data as well, but by putting these tools in the hands of the designer it is allowing the industry expert (i.e. electrical engineer) the ability to choose and define what is a true error and not someone unfamiliar with the data (i.e. GIS specialist) that may not.

One of the other benefits in using AutoCAD Map 3D and its drawing cleanup tools is it allows an interactive approach to error correction. That means that instead of blindly relying on the software to determine an error and a fix, the user has the last validation in determining the course of action to be taken. It can be fixed, marked for further review and manual correction, or fixed using the user-defined error tolerance.

Adding Descriptive Information for Design Data

One of the largest misconceptions around CAD data from GIS professionals is that it doesn’t have the descriptive properties used in a GIS. AutoCAD Map 3D has the ability to append descriptive information called ‘object data’ to any AutoCAD object. This information can be used to generate dynamic labels reducing manual updates later for the CAD designer; however, more importantly these attributes can also be transferred with the data during export. That means that after the design phase, the AutoCAD Map 3D user can choose to include these descriptive properties when exporting to a GIS format like a .SHP or .TAB reducing manual and often tedious updates in the GIS.

Adding Context with Coordinate Systems

As a GIS is geographic in nature needs information that has a coordinate system to establish position relative to its location on the earth. AutoCAD Map 3D currently supports over 4000 different projections and coordinate systems allowing design information to meet the needs of a GIS. This means that a designer can start their project in the appropriate coordinate system that will be recognized by a GIS mitigating the issue of manually changing this and potentially changing the accuracy of the CAD design.

In addition to being able to support coordinate systems, AutoCAD Map 3D has the ability to take existing non-georeferenced data (information without a coordinate system) and apply the appropriate coordinate system to it. This means that an AutoCAD Map 3D user can take design information from a .DGN or .DWG that is currently in an arbitrary coordinate system that would not map to a location on the earth and using the ‘transform’ command, place that information correctly into real-world coordinate space while preserving the integrity of the original engineering.

Reaching Optimum Productivity

By using AutoCAD Map 3D as the design platform the CAD drafter or engineering designer can prepare the design data for its use with GIS, ultimately increasing the value of a GIS to an organization through its use of precise and accurate data and minimizing costly, error prone processes. Organizations that have made the investment in both AutoCAD and a GIS will have a short learning curve in achieving a more productive data workflow because at the core, AutoCAD Map 3D has all the feature and functionality of AutoCAD, but with the extended tools and capabilities to make design data GIS ready.