Modernizing Paper Engineering Drawings

Using the proper electronic document conversion technique is proving to be a competitive edge for many companies.

By David J. Wilson and Scott Harlin

The Raster Editing Process
The Raster-To-Vector Conversion Process
Summary
About the Authors

To compete in today's world, a company has to survive in a fast-growing, technologically driven environment of producing goods and services. How does a company develop the best product or service delivered to market at a fair price in the shortest time?

For a company to maintain this competitive edge, it has to leverage its assets which include a tremendous amount of engineering documents. Tools and processes to efficiently modify these assets are essential. CAD provides the most productive environment in which to manage and modify engineering documents. In the United States, about 20 percent of all drawings produced are in a true CAD format, with another 25 percent serving as CAD revisions of older drawings. This leaves an astonishing 55 percent of drawings produced the old-fashioned way - with traditional paper and pencil drafting.

The challenge facing companies is how to best modernize the process for modifying the current paper documents - a cost which will exceed $1 billion with approximately 3.5 billion engineering drawings already produced at a rate of 26 million new drawings produced each year.

What do companies do with the 16 million draftsmen on drawing boards and the one million draftsmen using 2D CAD and the millions of engineering documents on paper produced manually? The solution is to bridge the paper and CAD worlds with affordable solutions.

Two major processes exist today in modernizing the paper engineering drawing process. They are direct conversion from paper to a raster database using raster editing techniques and direct conversion from paper to CAD using raster-to-vector conversion. This article will discuss both processes so that you can make an informed decision is you are faced with this problem.

Both methods have their place in today's organizations. The factors that will influence your choice include:

the specific application for your drawing
the amount of intelligence needed from your archives
your exisiting in-house expertise to perform the drawing changes
the sophistication and frequency of the drawing modifications

The Raster Editing Process

Raster editing is the simplest and most productive way to modify designs from paper drawings. By implementing raster editors, a company can leverage their drawing assets at a minimal cost for capturing the data. This approach has proven to be best suited for composition and non-intelligent applications, as well as for heavy distribution and restoration of archives.

Today's scanning technology allows for minimal capture costs. Low-cost scanners have reduced the capture costs to under $15 for an E-size drawing. This cost is less than half of what some organizations pay, on average, to retrieve one drawing from a company's paper document department.

Distributing engineering documents in an electronic format is quickly becoming the standard means of distribution within companies. The great advantage of electronic distribution is the increase in information flow. The greater the speed of information exchange, the greater the overall efficiency in communications and decision making. Hence, the reasoning behind the Department of Defense's mandated Computer-Aided Logistic Support (CALS) initiative, which ties in networking, low cost scanning, database management, and electronic viewing, in a variety of price ranges and solutions, for the sole purpose of adopting and standardizing imaging capabilities. Raster editing is also ideal for restoring old and worn drawings. Once a company captures a drawing in an electronic raster format, the deterioration of the drawing ends and the drawing can undergo improvement by raster editing techniques.

Not all raster editors are alike, however. There is a distinctive productivity improvement realized as the intelligence of the editors is increased. The early raster editors were paintbrush tools which allowed compositional editing similar to cut and paste operations, and allowed for pixel painting.

These techniques fit well in graphics and illustration applications, but not in engineering design and modification.

The next generation of raster editors were hybrid systems which emerged from the CAD and imaging vendors found in the market today. These systems took advantage of CAD geometry construction combined with raster paintbrush techniques to further improve drawing productivity.

At a higher level, the third generation of raster editors extends the intelligence by treating raster data more like intelligent CAD primitives and brings the editing process closer to the productivity of the CAD system.

A comparison of hybrid and intelligent raster editing shows significant differences in the methods used to modify an image. In the revision process, the hybrid approach uses erase and redraw methods, while the intelligent raster editing modifies the actual geometry as a CAD system would, which in turn preserves the integrity of the image.

Both methods use CAD commands to insert new geometry in a rasterized format. Also, both use cut and paste for composition editing. However, intelligent raster editing allows users to select an area with a window, where they can "unpick" portions or objects that do not need to be cut.

In addition, there are selective intelligent raster editing systems that can provide global smoothing of restored drawings, and can skew and scale to compensate for scanning distortion. Object despeckle and hole fill, as well as raster/vector snapping and rectified smoothing features separate some of the outstanding systems from mediocre ones. But users will want a system that can preserve a drawing's geometric integrity in raster format.

The most important consideration with any raster editing process is its ability to provide fast turnaround on drawing revisions. The cost savings associated with storage facilities and document personnel is minimal compared to the savings in the revision editing and retrieval processes. The intangible savings is the ability to increase the velocity of information flow within an rganization, which in turn, reduces design and manufacturing efforts and improves time to market.

As their name implies, raster editors allow for editing in raster format for quick and cost effective drawing modification. They are in no way intended to work hand in hand with vector data as it relates to parametric design, manufacturing and analysis. A raster-to-vector conversion system is best suited for these requirements.

The Raster-To-Vector Conversion Process

The true vector conversion process is expressed in terms of higher level entities used for analysis and modeling that will help leverage information assets by using existing CAD production assets. This conversion process enjoys the best of both worlds. The distribution and archival value of raster information co-exists with the design, construction and analysis of vector information.

Conversion enjoys the raster benefits of composition editing, drawing restoration, archival storage and distribution with vector benefits of vector benefits of vector converted attributes, geometric construction tools, parametric design and drafting and manufacturing and analysis.

The vector conversion process can be accomplished a number of ways using different levels of automation tools. For example, the most labor intensive approach is to simply re-enter the drawing using CAD, by using the hard copy as a template to digitize the drawing into the CAD system or by scanning the drawing into the CAD system using the raster image as an overlay on the screen. These three approaches are manual or semi-manual and take a relatively long time to complete.

The automated conversion approach implies that a combination of software and/or hardware is used to convert the scanned raster image into a file of CAD entities. While advances in artificial intelligence, neural networking and pattern recognition continue to offer more automation, it is user-assisted selective conversion that offers the best throughput. More intelligent solutions allow for complex raster object selection and apply user supplied rectification rules to complete the conversion.

Most of the time, the automated conversion process will require user verification and correction using clean-up editors. However, an automated conversion program will take approximately four hours to complete an E-size drawing and from 8 to 40 hours using conventional digitizing or overlay approaches.

The economic feasibility of automated conversion depends on anticipated volume, intended use of the converted drawing and the quality of the originals. Presently, there are a number of service bureaus which act as conversion houses that manually digitize drawings. They have a large investment in equipment and personnel training. Their customers are typically larger firms in the aerospace, government sub-contract and utilities industries who pay $1600 to have one E-size drawing digitized into a CAD system. At $1600 per drawing, it takes only three complex manual revisions to pay for the conversion.

At $1600 per drawing, however, the cost is prohibitive for the mass market, and is why cost-effective scanning and conversion programs have emerged. Though th e mass market is emerging, it is doing so at a slow rate due to unrealistic expectations and customer reluctance in accepting the new technology.

In order to reach mass market appeal, there are four basic criteria required for acceptance of these conversion tools, including:

proven solutions
easy implementation
payback certainty
high efficiency

In the age of electronic innovation, six months can be counted as a mature solution if the solution fits the need. Raster imaging has arrived as a simple, mature solution, with the early CALS initiative providing a set of standards around which new products can be built. There are currently a host of software and hardware products available to meet this requirement.

Easy implementation means the acceptance of the tool by company personnel expected to use it and gain from the technology. Raster editing and conversion have evolved as add-on tools, allowing the customer to implement the tool inside an already existing and familiar CAD system.

Affordability and high efficiency are key ingredients in the acceptance of any new technology.

When compared with manual revision processes, the savings of electronic revision is extraordinary. The speed of the CAD revision coupled with the raster editing tool allows customers to afford a low front-end cost with impressive efficiency gains and cost savings.

Summary

Converting paper engineering documents to electronic format is a process that companies must undergo in order to compete in the world market. The substantial time and cost savings realized in the utilization of CAD dictates that processes must be implemented to speed the revision process and information flow within engineering disciplines.

Converting to electronic format can be either direct conversion to CAD using automatic raster-to-vector techniques or through a raster database. Automatic conversion responding to these needs will save billions of dollars in conversion and tens of billions of dollars in automating the current paper process.

As the demand for scanning increases, raster editing features will emerge to further automate the raster processes. Just as CAD vendors have responded with better and faster features, so will the raster product vendors. Products are now available with more intelligent conversion and enhancement including selective and rectified vectorization, integrated raster/vector snapping, grips raster editing and global smoothing. In the future, features will include text recognition and area tagging for database drawing attributes. With intelligent object picking available today, this new set of tools reduces costs and increases productivity in the image modification process.

About the Authors:

David Wilson is Principal of Open Archive Systems, a New England-based company specializing in paper-enabling solutions.

Scott Harlin is Vice-President of Green Light Communications, a Los Angeles-based marketing organization that specializes in high-tech applications.