Frequently Asked Questions

1. Is it better to scan microfilm or the original plans?
This depends on several factors:

• Which is in the better condition?
• Has the original plan been modified since being microfilmed?
• Aperture cards are normally scanned to a standard size, e.g. A1. Hard copy drawings are scanned to their exact original size.

If they are both in the same condition, scanning the aperture card is better.

2. After the microfilm or plans are scanned, what do I receive?
You will be supplied with a raster (image) file.

3. What is a raster file?
A raster file looks like a series of lines but is, in fact, a series of dots close enough to appear as smooth lines.

4. Can I modify the raster file in AutoCAD?
A major breakthrough is available in AutoCAD R14 with regards to raster files. The following is a description down-loaded from Autodesk’s Web site:
Scan paper drawings into AutoCAD
"Now, for the first time in AutoCAD, you can display and plot raster images – like scanned drawings and colour photographs – in AutoCAD software as a standard selection, just like vector drawings. Combine raster images with AutoCAD vector graphics to create hybrid drawings, control the order in which they display, tailor the images, and improve performance. These tools save time by letting you use existing paper drawings, like as-built drawings of older structures or mark-ups, in AutoCAD without having to redraw them."

5. What is vectorisation?
Vectorisation is the conversion of raster files to vector files. This involves converting the series of dots to lines. The programs that do this conversion currently achieve 80% success. The resulting vector file would need to be cleaned up. The amount of clean up depends on the quality of the original drawing. Text does not convert well if it is hand written on the original. Despite these difficulties, it is generally quicker and far less expensive to use this process than to redraw.

6. Can you vectorise the scans for me?
We offer a service to convert your raster images to vector files. The final clean-up can be done on your own CAD system, or ours. Our CADPerfect solution provides a drawing that is indistinguishable from one drawn from scratch in a CAD program.

7. What resolution should I scan at?
The most commonly used resolutions range from 200 to 400 dpi. More detail is picked up at higher scanning resolutions, but the cost in file storage is also higher. Do not, therefore, automatically choose the highest resolution every time. We use 300 dpi for line drawings.

8. What size are the files?
The higher the resolution, the larger the image file and the increase is exponential. An A0 scanned at 300 dpi would be approximately 400 Kb. The same drawing scanned at 400 dpi would be 800 Kb.

9. Can I view these files?
Utilities are available to view and print the images. The cost can vary greatly depending on the complexity of the program you require.