OVERVIEW

CHAPTER SUMMARY

This chapter describes strategies for dealing with paper, and provides a rationale for not dealing with paper. If your firm deals with drawings on paper, then this chapter describes some of the problems and solutions to dealing with them.

Many of the previous chapters (indeed, most books on CAD) tell you how to create drawings in CAD. But what about the drawings that already exist on paper? The toughest problem in CAD involve inputting old paper drawings into the CAD package.

Thanks to fast plotters, CAD software easily generates paper drawings. The reverse, however, is much more difficult. It is difficult to change a paper drawing into a digital equivalent. The primary method is to employ a scanner to read the paper drawing, and save the scan as a raster file essentially, taking a digital "photograph" of the lines on the paper.

Creating the raster file is the easy first step; the difficult second step is to convert the raster file into a vector drawing understood by CAD software. This chapter describes the variety of techniques invented over the last 20 years to solve the problem of raster-to-vector conversion.

A project consists of more than just CAD drawings; there are contract documents, photographs, and marketing material as well. A scanner manufacturer ^[1] created the following list of documents that their scanners have handled:

• Architectural drawings

• Engineering schematics

• Aperture cards

• Manufacturing diagrams

• 35 mm film

• Slides

• Transparencies

• Big posters

• Original art work

• Story boards on up...