Raster to Vector – Getting Accurate Conversions
What accuracy can you expect from raster to vector conversion?
Like so many seemingly simple questions, the answer is actually somewhat complex, because there are so many factors that contribute to the accuracy of the final converted CAD drawing. There is the accuracy of the method of conversion, coupled with the abilities of the person doing the conversion, as well as the accuracy of the original scanned drawing. A slip up in any one of these areas can make for the loss of accuracy, and the loss of accuracy can grow exponentially with each additional missteps.
First of all, let’s define accuracy.
How accurate is accurate?
It’s important to have realistic expectations as to just how accurate a raster to vector conversion can be. Generally speaking, most companies are happy to have an accuracy tolerance between +/- 0″ and 0.01″ in ideal circumstances. That means that for most companies if they have a highly accurate scan, accurate software and an experienced operator they can get ‘pretty good accuracy.’ But what happens if ‘pretty good’ is not good enough?
One company, CAD CAM Services, Inc., has perfected a method for achieving an accuracy of +/- .005″ in the paper to CAD conversions. As a result of this success, they are one of the few companies in the world that are certified by the Department of Defense for CAD Conversion work. This high accuracy is a requirement for both the military and the aircraft industries.
CAD CAM Services, Inc. provides a deliverable product that is a truly Perfect CAD drawing with real lines, arcs, circles and text as text. At the minimum, each drawing is produced with 3-7 layers and colors and delivered in nearly any native CAD file format required.
How important is the scan?
When you’re talking about automatic vectorization, the single most important ingredient for good results is poor quality scanned images. If you have a good quality scanned image, it is often possible to get reasonably good results by using a good quality, reliable vectorization software. However, with a poorly scanned image, using an automatic vectorizer and getting reliable results becomes far more unlikely.
This is where a high-quality CAD conversion service that uses qualified, experienced conversion engineers can be a huge asset. Experience raster to vector conversion engineers can provide a seamless blend of vectorization techniques along with editing and drafting skills that result in drawings that are sometimes better than the original.
Why are some scanned images better than others?
There is two determiners of scan quality: (1) scanner quality; and, (2) operator know-how. Because scanner manufacturers and resellers out the easy usage of their scanners, many companies assume that inexperienced employees can do the job of creating scanned images raster to vector conversion.
While it is true that most large format scanners that are sold today are mechanically reliable and push-button easy, unfortunately, it does take a large measure of conversion experience to understand just what buttons need to be pushed to get the final scanned image that will result in high-accuracy raster to vector conversion.
It follows that using an experienced CAD conversion service for both your large format scanning and your raster to vector conversion will provide you with the best and highest accuracy final CAD product. However, sometimes it’s not possible to use this magic combination. If you have received raster images from another source and do n’t have the ability to rescan poor images, you will need to rely on an expert who can not only do the raster to vector conversion but can also do the appropriate editing and drafting prior to beginning the vectorization process.
Some of the issues that may need to be corrected before the raster to vector process take place include:
- Fixing broken entities and smoothing curves
- Reducing noise in white spaces
- Cleaning speckles and discolorations
- Rubber sheeting to create parallel lines
- Correcting erroneous drafting
- Cleaning text characters
- Recreating drawings that cannot be fixed for vectorization
Highly accurate raster to vector conversions are possible, even for high tolerance applications such as military and aircraft, and CAD CAM Services, Inc., is one company that is highly capable in these areas.