How an old map gets into the Internet
1) Test scan
Before scanning test scans are needed for each map. I run through so many settings until the street names (by a resolution of 1024*768 on a 17 inch monitor) are readable and the colours as near as possible to the original. I note the setting and use it in the subsequent scanning.
This is done bit by bit with a good flatbed scanner. The scanner must be furnished with good optics as well as a bright light, otherwise elevations will appear blurred and dark. For that purpose I use the Mustek A3SP.
<-- Here is a view of my "Workshop."
3) Assembling the Parts
Even with a good level support of the image processing program, you will need much patience and careful eye-balling to push the individual fields together. Each Scan lies on its own level which I eventually fix on one level as soon as all transitions are smooth and fit perfectly together. The result is a rather monstrous Pixel picture. The GDR map of 1989, for example, has 7700 * 9800 Pixel with an uncompressed load of 450MB!
4) Dismantling the Parts
Yes, you hear correctly! Now you may ask why earlier I joined the individual scans to a complete picture only to dismantle the plan again into separate parts. There are two reasons: 1. The loading time on the Internet, even with an 85 percent JPEG- compression, would be still too high (also with DSL!) and 2. With only small and individual map details navigation becomes easier and there is no need to use the scroll on the browser window.
The Tourist-Publisher-Map (GDR) I have divided into 3850! small JPEG frames using my picture adapting software.
5) Determining the Position
If, for example, I want to compare an old map section with current developments, I need to integrate the map with the geographical coordinate system. For that purpose I determine the outer margins (up, down, left, right), the northerly width as well as the easterly length. For that I use PERL, which is a tool that I have designed to calculate rotation (with the help of free GIS-DATA), because for old maps the take is not exactly precise.
6) Formatting the Navigation Window
Now, almost at the end, I make a small picture of the map (maximum 200 Pixels wide), that I link on the left side, above the corner, and that serves me as navigational help.
Specific map data, that my Perl Program needs for the calculation of information, is recorded in a small data bank and is then, together with the picture frames, uploaded on a UNIX-Server in the net.
Expenditures and Time Needed
The time needed from scanning to uploading is immensely high. For the Pharus Plan of 1921, I have invested 10 hours pure working time, not considering the computing work of my poor PC. The copy shop work goes faster. Unfortunately it is expensive: a scanned map costs 30 euros plus 10 euros for burning expenditures. A further disadvantage: With the large DIN A0 Scanner working in the moving procedure - there is the danger of damage and distortion.
How I will decide, I do not yet know. I have many maps in my possession that I want to put on the net, so I really need to find a compromise.