documented, and gets changed every couple of years, no one ever figures it out perfectly. Thus, exchanging DWG files with non-Autodesk programs always involves some compatibility risks.
When you send DWG files to other people — whether they use AutoCAD or a different CAD program — you need to make sure that their software can read the DWG file version that you’re sending. See Chapter 1 for information about AutoCAD DWG file versions.
When you send DWG files to other people, remember to use the ETRANSMIT command to ensure that you send all the dependent files (fonts, xrefs, and raster images). See Chapter 16 for details.
DXF
DXF (Drawing eXchange Format) is the Autodesk-approved format for exchanging between different CAD programs. (Some other vector graphics applications, such as drawing and illustration programs, read and write DXF files, too.) DXF is a documented version of the DWG format. Because DXF more-or-less exactly mimics the DWG file’s contents, it’s (usually) a faithful representation of AutoCAD drawings.
How well DXF works for exchanging data depends largely on the other program that you’re exchanging with. Some CAD and vector graphics programs do a good job of reading and writing DXF files, while others don’t. In practice, geometry usually comes through well, but properties, formatting, and other nongeometrical information can be tricky. Test before you commit to a largescale exchange, and always check the results.
To create DXF files, use the SAVEAS command (File>Save As) and choose one of the three DXF versions in the Files of Type drop-down list. To open a DXF file, do the same with the OPEN command (File>Open).
DWF
As Chapter 16 describes, DWF is Autodesk’s special “lightweight” drawing format for posting drawings on the Web or sharing them with people who don’t have AutoCAD. Those people can use Autodesk’s free Express Viewer program to view and print DWF files (as well as DWG files). Chapter 16 describes how to create and use DWF files.
Adobe’s PDF (Portable Document Format) is the most popular format for exchanging formatted text documents among users of different computers and operating systems. PDF also does graphics, as you probably know from having viewed PDF brochures on Web sites.
Autodesk has worked hard to make DWF the PDF for CAD drawing exchange, but DWF hasn’t yet caught on in a big way. When AutoCAD users need to send drawings to people who don’t have AutoCAD, many prefer to convert the drawings to PDF files. Most potential recipients are familiar with PDF and already have the free Adobe Reader installed on their computers, neither of which can be said of DWF.
The free Adobe Reader views and prints PDF files, but won’t create them. In order to convert an AutoCAD drawing (or any other Windows document) into a PDF file, you’ll need additional software. Adobe sells Acrobat Standard and Professional for this purpose — see www.adobe.com/acrobat/ for details and a trial version. Many other companies offer commercial and shareware PDF-creation programs. One such utility is Pdf995 (www.pdf995.com), which, despite its under-$10 price, does a good job of creating PDF files from AutoCAD drawings.
WMF
There are lots of different vector and raster graphics file formats, but Microsoft has been pretty successful at making its WMF and BMP formats the
WMF (Windows MetaFile) is a vector format, so it does a decent job of representing AutoCAD objects such as lines, arcs, and text.
To create a WMF file showing some or all the objects in a drawing, use the EXPORT command (File>Export) and choose Metafile (*.wmf) in the Files of Type drop-down list. After you create a WMF file in AutoCAD, use the other program’s file insertion command to place the image in a document.
AutoCAD puts objects in the WMF file with the colors and display lineweights that you see on the AutoCAD screen. To create a WMF file that looks like a
You can go the other direction, from a WMF file into AutoCAD, by using the WMFIN command (Insert>Windows Metafile).
BMP, JPEG, TIFF, and Other Raster Formats
BMP (BitMaP) is the standard Windows raster format. AutoCAD can create BMP files from drawing objects (via the EXPORT command) and place BMP
files in drawings (via the IMage command). When you export AutoCAD drawing objects to a BMP file, all the objects get converted to dots. Turning a line into a bunch of dots isn’t a swell idea if you want to change the line again. But it is useful if you need to copy a drawing into a company brochure.
One problem with BMP files is their big file size. Unlike some other raster formats, BMP doesn’t offer compression. Because CAD drawings usually are fairly large in area, they can turn into monstrously large BMP files. Creating a BMP file showing some or all the objects in a drawing is just like creating a WMF file: Use the EXPORT command (File>Export) but choose Bitmap (*.bmp) in the Files of Type drop-down list. After you create a BMP file in AutoCAD, you use the other program’s File>Open to open it or the graphics file insertion command to place it in an existing document.
If you want to go the other direction, a BMP file into an AutoCAD drawing, use the IMage command, as described in Chapter 13.
Although BMP is a standard Windows format for exchanging raster data, it’s certainly not the preferred format of many programs. Other common raster formats include PCX, JPEG, and TIFF (the latter two appears as JPG and TIF in Windows). Among their other advantages, these formats offer image compression, which can reduce the size of raster files dramatically.
If the program that you’re trying to work with works best with other formats, or you want to avoid huge BMP files, you have a couple of options:
? Create an AutoCAD-friendly format (such as WMF or BMP) and translate it to another graphics format with a translation program such as HiJaak (www.imsisoft.com) or VuePrint (www.hamrick.com).
AutoCAD includes new JPGOUT, PNGOUT, and TIFOUT commands for creating JPG, PNG, and TIF files in the same way that you export WMF and BMP files. Type the command name, press Enter, specify a raster file name, and select the objects to be included in the image file. These commands use the current drawing area background color as the background color for the image. If you want your image background to be white, make sure
