LT On-line: Lesson 3

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

Figure 1.

Exchange acronyms
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.

OLE
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.

Figure 2.

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.

WMF
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).

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.

BMP
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.

Figure 4.

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.

From LT to Word
  Page 1: Introduction and exchange acronyms
  Page 2: Creating a WMF in AutoCAD LT
  Page 3: WMF file preparation
  Page 4: WMF process details
  Page 5: Placing a WMF file in a Word document