Map production and reproduction


Cartographic production: changing technology
each period's equipment remains in some uses - partial replacement
(also each period leaves a legacy in methods of doing the job)

Manual approach : pens and paper (manuscript maps)

Printing technology: methods to deposit ink

Raised relief printing: woodcut, letterpress (now photographic)
Engraving (image removed): etching on copper
Lithography ("drawing on stone") [based on greasy ink]
color printed through "process color" (cyan, magenta, yellow, black)

or even more color inks. European mapping: one ink per color.

Transfer from manuscript to printing plate

(Ch. 16 of Dent): linkage from technology to product
Woodcut era & engraving era, specialists understood limits
Early litho transfer permitted untrained cartographers
Then 1950-70 revival of connection from photo process to press

Definitely broken by computer technology

Optical enhancements (parallel processors) permitted through photography

process camera and film emulsion negatives and positives
Half tone (continuous art work broken up by screens: dots or lines)

Screen tints (permit control of grey / less intense color)

Replacements for pen and ink

scribing tools (replace pen, remove material not deposit ink)
masks (keep light off areas not relevant)
peelcoat (cut with knife/scribing tool and lift off areas)
Automated plotters: pens, scribe tools, photo heads

Laser printers & typesetters: from 300 dpi to 2560 dpi : the real revolution

Viewing the graphic as a set of "layers"

a view created by color process
initially, layer is whole color separation (flap) (constrained by output)
each color plate is a black/white image. If different intensity is required, then separate B/W images must be screened and combined (multiply exposed) onto the composite output.
Example: red layer has roads; Interstate 80% screen, streets 40%...

Sherman's Multipurpose Cartography: (pre-computer)

Layers defined by attributes, combined AS NEEDED.

Approach develops from practical use of equipment & techniques

Version of 26 March 2003