Introduction

Learning by doing, gathering experience by making mistakes, two milestones on my learning curve. Specially in the case scanning.

Orientation

If you want to scan a map in one piece you need an A0 or an A1 format scanner. Those aren’t affordable. If you have an A3 or an A4 scanner there is an alternative. Divide your map in sections, scan these sections and stitch them together with a graphics program. Try to orientate the map sections exactly with the same angle on the scanner. This prevents a lot of calculation or trial and error.

Overlap

If you want to stitch the multiple scans together make sure the scans overlap. Also, make sure, that you have multiple recognizable points in the overlap area. Try to find combinations of horizontal, vertical and diagonal lines. You need these recognizable points when stitching them other.

Resolution

When scanning a map it is important to use the correct scan resolution. Read my note "Relationship between scale and resolution of a map". From my own experience I know that a resolution of 100 pixels per cm (or 254 pixel per inch) suits best. When your scanner doesn’t support 254 pixel per inch opt for the default resolution of 300 pixel per inch. Although a higher resolution provides detail but makes the scan of the map section unnecessarily large. Sometimes it is useful/necessary to choose a higher resolution. This occurs when you stich multiple sections together. It can give you just a little more slack. After stitching you can reduce the resolution to 254 pixel per inch. Before starting a major project, do get some experience (by trial and error).

Color depth

Many scanners have the ability to select the color depth. The default setting is usually 16 million colors (this is a color depth of 24 bit). In most cases this setting fits best. When all the stiching is done the depth can be reduced to 256 colors (8 bit). Of course you can experiment with scanning with a color depth of 8 bit, but your graphics program you use for the patchwork, must also cope with this color depth. PhotoFiltre, I often use, isn’t able to handle cut and paste actions with a color depth of 8 bit.