LT On-line: Lesson 31 Mar, 2000 By: Mark Middlebrook
From LT to Word
Page 1: Introduction and exchange acronyms
At various times,
you probably need to paste a drawing into a report or other word processing
document. If you've run into problems using ordinary Windows cut-and-paste
There are several ways to transfer drawings from AutoCAD LT to a word processor or other Windows program, but not all of the methods work well. The three most common methods are OLE, WMF, and BMP.
Although Object Linking and Embedding (OLE) is the standard Windows way of exchanging data between two programs (figure 2), OLE is afflicted with numerous practical problems.
First, compound OLE documents can slow down
performance--sometimes a lot. Second, supporting OLE well is a difficult
programming job, and many applications, including AutoCAD LT, suffer from
OLE design limitations and bugs. Third, getting consistent hard-copy output
can be tricky, especially when you plot from AutoCAD LT. OLE objects that
look fine on the screen often undergo amazingly creative but not necessarily
desirable transformations when they come out on paper. In my experience,
the potential benefits of using OLE with AutoCAD LT just aren't worth
all the pitfalls and limitations that you have to work around.
You can create a WMF (Windows MetaFile) from all or some of the objects in an AutoCAD LT drawing with the Export or Wmfout command (figure 3).
The WMF file includes a vector representation that's fairly faithful to
the graphics in the AutoCAD LT DWG file, which also uses a vector format.
(A vector format stores graphics as collections of geometrical objects,
such as lines, polygons, and text. Vector graphics are good for high geometrical
precision and for stretching or squeezing images to different sizes. These
two characteristics make vector formats especially suitable for CAD.)
Many other Windows programs, including Microsoft Word, do a decent job
of importing WMF files. I've found WMF to be the most reliable and efficient
way to transfer drawing graphics to a Word document.
The other common format for exchanging graphics between Windows programs is BMP (BitMaP). Although the Bmpout command in AutoCAD LT creates a BMP file from all or part of a drawing (figure 4), BMP usually is a bad choice for representing vector graphics of the sort that appear in CAD drawings.
For one thing, most CAD drawings turn into monstrously large BMP files.
As an example, I opened a small 100KB DWG file showing a simple house
plan and exported it to both WMF and BMP formats. The exported WMF file
was about the same size as the DWG file, while the exported BMP file was
over 2 MB! Another problem is that BMP is a raster (or bit-map) format.
A raster format stores graphics as a series of little dots, or pixels.
Raster graphics are good for depicting photographic detail and lots of
colors, but not so good for most CAD drawings.
Autodesk Technical Evangelist Lynn Allen guides you through a different AutoCAD feature in every edition of her popular "Circles and Lines" tutorial series. For even more AutoCAD how-to, check out Lynn's quick tips in the Cadalyst Video Gallery. Subscribe to Cadalyst's free Tips & Tools Weekly e-newsletter and we'll notify you every time a new video tip is published. All exclusively from Cadalyst!