الخميس، نوفمبر 26، 2009

Large-Format Scanning -- Key Considerations



When documents are larger than legal size paper, you need to think about a few extra steps to ensure proper capture. To paraphrase the warning on rearview mirrors, "Drawings in computer are bigger than they appear.”

As a service provider for large format scanning, I’m often confronted with the mistaken belief of many that scanning large-format documents is simple. It’s not! These types of projects are larger and have hidden costs and traps. Based on my experience, I will share how to be productive with a large format scanning production and the process. Here are some key considerations for any large-format project.

Document Prep
Large-format drawings can require a lot of repair and preparation. Pulling staples, removing notes, taping up torn edges, and the like can involve more than you think. You may also need to remove the drawings from sticks (hanging racks) or books. Large documents are often rolled up and stored (sometimes for decades) in pigeon holes. Drawings that have been rolled for long periods of time need to be either reverse rolled or flattened out for at least 48 hours.

Staples can be located in the middle of a drawing with a document attached. Understanding the goal of this data is critical before you begin. Many times, clients will tell us that there aren’t any documents or notes on the drawings. However, there are ALWAYS exceptions (I’m tempted to say that, at times, exceptions are the rule). Be prepared.

In addition, there can be dust (from storage) which needs to be vacuumed from the drawings. Dust can damage a scanner’s glass, so you must address this issue up front. Remove as much dust as possible to avoid replacing the glass. A scratch in the glass can look like a piece of dirt and create a line on the drawing that is not there.

No laundry service for drawings. Don’t be surprised if you have to get an ironing board and iron drawings to get them flat. We have ironed drawings on previous projects to get them flat enough for scanning. Just glad we were scanning a hotel’s records -- they provided the iron and ironing board. ;-)

Sorting
Some projects are more effective when the drawings are sorted by size and/or by quality. This minimizes the amount of time spent changing settings during the scanning process. There are limitations to length with PDF and JPG formats. You can scan beyond 100 inches but you cannot have it in a PDF format. PDF will not allow you to exceed 100 inches.

Control Numbers
During all projects, we apply a unique ID number (sequential). This number helps identify that the drawing has been scanned. Because of the varying types of media, we have selected stickers (opposed to a bates stamper) because ink will bleed on mylar. It also helps with quality assurance issues.

For example, one client took the scanned drawings and moved them to another location. A few years later and with new staff, they were identifying drawings that needed scanning. The Control number, which was a small sticker with a sequential number, was the only way they were able to identify if these drawings had been scanned, allowing them to avoid duplicating work.

File Naming
Special file naming when drawings will be indexed into a database is, in my opinion, a waste of resources. If you don’t have a document management system, then this makes sense. If you are scanning projects (sets of drawings) you can batch file name the project for all drawings and have sequential numbers follow the project name.

You can also do simple batch file naming with two or three characters in the beginning of the file name and then the sequential numbers to follow. This works for separating facilities or other types of categorization without special file naming.

Scanning
Single page or multipage? Sets of drawings can be scanned as a single image or you can create a multipage document. Just remember that if you are scanning as a multipage document and have a color scan in the middle of it you may have backed yourself into a corner. Scanning to a multipage TIF will work with monochrome documents but you will need to change your format to a PDF to get monochrome and color images into one file. I am confident you will not want to have a color TIFF due to the size.

Color -- Or Not
Many times there is content within a drawing that distinguishes additional information. Highlighted data can become a black block if you scan it as a monochrome with incorrect setting. Scanning is grayscale or color allows you to capture the information so that data is as easily readable as is the original. You can also batch convert the grayscale images back to a monochrome images with software. This way you will always have the ability to adjust the image to enhance the image where you could not do this with a monochrome image.

Resolution
According to most agencies (as well as AIIM Standards), large format documents (which can be 11 x 17 or larger) should be scanned at 300 dpi resolution. Any less is not recommended even though you have a good original.

Quality Assurance
Most large-format scanning projects never get a Quality Assurance Check. All drawings should be verified with virgin eyes to confirm that the edges have not been cut off and that the setting were correctly set to capture the image at the highest quality. We sometimes find lines on a drawing that are not part of the drawing. This is often a piece of dirt that goes from the top to the bottom of the image. These need to be rescanned. A good scan tech will catch these issues and rotate the drawings to their proper orientation before Q/C.

Large format documents are in a separate world, but are the key to complete enterprise-wide document management.

Lisa A. Desautels (702-222-3590 orlad@graphicimaging.net) has been President of Graphic Imaging Services, Inc. ( http://www.graphicimaging.net/) since 1997 and has providing specialized Document Imaging Solutions for large format documents for more than 12 years. Her knowledge and experience with CAD (Autodesk) and GIS (ESRI) since 1991 allows her to bring a more holistic understanding of the issues around document management to her clients.


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