CADENCE Review of DRAWING Librarian Note: This review starts out with an overview of all products reviewed. If you wish, you can skip straight to the portion that deals specifically with DRAWING Librarian.

Drawing Viewers

14 Viewers to Sort, Collate, Redline, View, and Spindle AutoCAD Drawings

By Ralph Grabowski

The drawing (DWG) file viewer is among the most important of AutoCAD third-party products. Ironically, the DWG viewer is popular because it allows users to do without AutoCAD. In fact, the viewer's primary function is to display AutoCAD drawings outside of AutoCAD.

Ever since Cyco International first pioneered the product category with AutoManager in 1987, viewers have become increasingly sophisticated. In addition to displaying DWG files, today's viewers display drawing files from competing CAD packages, plotter files, and files in many popular raster formats. The DWG viewers have drawing tools (euphemistically referred to as "redlining"), the ability to plot and print drawings, convert between file formats, and hook into other applications via programming links.

There are several dozen DWG viewers on the market. Most run independently of AutoCAD under DOS or Windows, a few with UNIX, some inside of AutoCAD as an ADI application, and a couple are built into ADI display drivers. Most vendors have more than one version of their DWG viewer, usually a low-cost basic version (one even has a shareware version) and several extra cost add-on modules or a more expensive "full feature" version. Unlike other product categories among AutoCAD add-ons, we were impressed with how different the viewers were from different vendors.

To help narrow down the field, we asked all known vendors for their stand alone DOS or Windows based DWG viewers. That left out those viewers that run inside of AutoCAD or a display driver, and those that are meant for network based drawing management. We received 20 DWG file viewer software packages, of which we review 14 here. Of the six we did not review, five were subsets of a more expensive product, one was a beta, and one arrived on a blank, unformatted diskette; the replacement did not arrive in time.

What Do DWG Viewers Do?

DWG viewers perform one or more of the following tasks:

Naturally, not all products perform all these tasks. For this reason, you should match your requirements with each product's feature list to see which product best meets your needs.

Fast DWG Viewing

The original reason for the first DWG viewer was to display AutoCAD drawings faster than AutoCAD itself, which is notorious for its slow load times.

We created separate load-and-display tests for the DOS- and Windows-based products. The benchmark was in two parts: loading the program, then loading the Airport.dwg file, a 960K'3 drawing. We compared the load times with AutoCAD Release 12 for DOS and Windows.

DOS-based viewers load and display the DWG file in an average 35 seconds, nearly six times faster than Release 12. The fastest of the group is Cyco's AutoManager, at 27 seconds.

Windows-based viewers load and display the DWG file twice as slowly as the DOS group: an average of 77 seconds. Still, they are on average four times faster than Release 12 for Windows and three times faster than AutoCAD LT. The fastest is Cyco's AutoManager for Windows.

Unlike a raster image, there are many ways to view a vector image: last-saved view, extents, named views, 3D views, viewports, and Paper or Model Space. All DWG viewers offer a subset of the possible views none display named UCS views, perspective views, rendered views, or perform hidden-line removal. Some viewers have an option to display drawings in monochrome, which is useful for technical publishing.

Accurate DWG Viewing

Even though Autodesk has declared DWG the industry standard CAD file format, no third-party developer (other than one) has been given official access to the format of the DWG file. Thus, with each new release of AutoCAD, the programmers start all over again at guessing at the DWG file's binary format. Thus, DWG files might not be displayed with 100 percent accuracy.

While some of the viewers display Generic CADD GCD files, none display AutoSketch SKD files or files from Autodesk's other software products.

We used several files to ensure that the viewers display AutoCAD entities accurately. We noted errors by two viewers. Informative Graphics' Myriad Windows did not display some entities in the PumpSol.dwg; Kamel Software's FastLook Plus displayed the variable width polyarc in Layer300.dwg with a reversed taper. If you find errors in the display, contact the vendor who may have an update.

Accuracy vs. Speed

DWG viewers have an advantage in that they don't need to display the drawing as accurately as AutoCAD.

After all, you want to see the drawing, not edit it. All DWG viewers let you toggle settings for greater accuracy or greater speed. The settings include:

All viewers provide a subset of these settings. Figure 1 shows AutoManager with a detail of the Airport drawing with speed settings turned on. We tested all DWG viewers with settings toggled for fastest load and view times.

A related issue is graphics board support. A higher resolution (such as 1024x768 pixels) lets you see more detail (greater accuracy) than a lower resolution (such as 640x480); a coprocessed graphics board (such as an 85l4/A or 83) displays the drawing faster than a frame buffer (such as the commonly used VGA). Most of the DOS-based viewers display at 640x480 pixels or higher. All the Windows-based viewers naturally use whatever display driver that your Windows system is using.

Display DWG Data

A CAD drawing contains a lot of intelligence, and all DWG viewers let you examine certain details. Figure 2 shows SoftSource's DL Windows displaying drawing data in independent windows.

The feature I find most useful is being able to display the individual blocks, block names, and pinpoint their locations in the drawing. Some viewers display the block in a dialogue box but not its location in the drawing.

Most viewers give you full control over layers. They list the layer names and toggle the display of layers. Cyco's AutoManager even lets you change the layer color and linetype.

Other data displayed includes time of creation, AutoCAD version number, attribute information, and named views. Kamel's FastLook Plus and AutoSight's ProView were the products that provided the most information.

Launch AutoCAD with DWG

Once the drawing is displayed by the viewer, it can be loaded into AutoCAD, making the viewer a front-end to AutoCAD and allowing you to manage drawings outside of AutoCAD. Slick for Windows and the DOS AutoManager have the greatest flexibility -- you can launch AutoCAD with the drawing as a drawing, a block, or as an external reference .

While most of the Windows-based viewers let you load a drawing by dragging the file name from the File Manager, Cyco also lets you drag the drawing from its Windows AutoManager into AutoCAD .

Vector and Raster File Viewing

In addition to doing the tricky job of viewing AutoCAD DWG files, all viewers allow you to look at files in other formats. The viewers that display the most common raster and vector file formats become a handy tool for any computer user. For example, during installation, you are asked if you want SirlinView for Windows automatically launched when you double click on any file ending in DWG, DXF, PLT, TIFF, BMP, PCX, TGA, GIF, WMF, and WPG. Such programs become the file viewer that's sorely needed by the Windows File Manager.

Informative Graphics' Myriad Windows and Cimmetry Systems' AutoVUE compete for the longest list of file formats. Myriad concentrates on file formats used in the engineering graphics. AutoVUE's includes file formats more familiar to desktop publishing.

Convert File Formats

Most (but not all) viewers translate between file formats. For example, you can convert an HPGL plot file into DXF or DWG format to load back into AutoCAD. Figure 4 shows Kamel Software's FastLook Plus drawing viewer. You can additionally use the viewer to translate DWG drawings into HPGL plot files for input into a desktop publishing package. But be careful, since the conversion capabilities vary widely among the viewer packages .

Compare Drawings

Since most viewers can display more than one file (using view-ports), you can compare two files to see if they have the same content. However, visual inspection is difficult in a cluttered drawing. Thus, some viewers let you compare drawings by other methods. AutoSight's ProView has the greatest capabilities in this area, as shown in Figure 5.

Printing and Plotting

All DWG viewers let you print and plot the drawings. This feature has become less important since Autodesk added the freeplot feature to Release 12. Some viewers let you group files for batch plotting.


Redlining lets you mark up drawings with lines (or polylines), arcs, circles, arrows, and text. Other drawing elements include rectangles, leader notes, and clouds. SoftSource's Drawing Librarian DOS goes one step further than the others and lets you define redline blocks, as shown in Figure 6. Most viewers let you create a number of layers (each with its own color) for redlining, which helps separate markings made by different people.

All viewers with redlining also let you edit the redline entities. The editing capabilities vary widely, but all viewers allow you to erase redlines. Slick/386 DOS has the greatest capabilities, down to a user interface that looks very much like AutoCAD's (see Figure 7). Slick DOS lets you move, copy, delete, and change text, as well as snap to geometric features (object snap).

DWG viewers do not directly modify the DWG file to ensure the integrity of the original file. Thus, the redlining and notes are imported back into AutoCAD as a separate DWG or DXF file. Since you can redline a new (empty) drawing, that makes the viewers a simple DWG-compatible drawing package.

In addition to redlining, most viewers measure distances. A very few also let you measure perimeters and areas.

Overlay Files

Some viewers let you overlay raster and vector images. That feature turns them into rudimentary raster-to-vector converters, since you can trace over the raster image with the viewers' redlining drawing tools. In Figure 8, CadmanView shows a redline tracing over a raster image over an AutoCAD drawing.

Other Features

Some viewers include advanced features not reviewed here. A number of them let you set up and modify links to databases. SirlinViews/Plus and Drawing Librarian Professional take the links feature to a greater extent than any viewer. You can connect text, database information, and even other drawings together (see Figure 9).

Some of the viewers include a programming interface that lets you control the DWG viewer from another application. This feature lets you display an AutoCAD drawing from within a database program, for example. Kamel Software includes sample code for linking FastLook Plus with Paradox, Visual Basic, Superbase, and Microsoft Access.

How We Tested DWG Viewers

In addition to noting product features, we tested for two crucial selling points: speed and accuracy. When you want to see a drawing file, you want to see it much quicker than AutoCAD can bring it up. And when you see the drawing, you don't want an inaccurate representation, such as missing or incorrectly drawn entities.

We tested the speed and accuracy of the DWG viewers against AutoCAD Release 12 for DOS and Windows on a 40MHz 386 with 8MB RAM, DOS 6.2, Windows for Workgroups 3.1, and 12 MB virtual RAM. The test drawings were those used to test DWG translators (CADENCE, March 1993): Layer 3OOldwg for Release 12 accuracy, Airport.dwg for speed, PumpSoLdwg; for AME: accuracy, Wrench.dwg; for Region accuracy, and Site-3D.dwg for Xref and Paper Space accuracy.


DRAWING Librarian Professional
DL for Windows

SoftSource provides its DOS DRAWING Librarian in three levels: Junior ($125) just displays drawings; Standard ($250) adds more file formats, translation, and printing; and Professional ($500), which is reviewed here, plus the Windows version called DL for Windows ($99), also reviewed here.

DRAWING Librarian Standard an Professional display up to 25 drawings in tiled viewports but are limited to displaying just DWG, DXF, SLD, BAK, HPGL and PCX files. Conversion is limited to DXF, SLD, and HPGL formats.

DRAWING Librarian Professional has the unique ability to group up to 25 drawings by a single project name. This feature lets you view, copy, and delete all drawings in a single project. Another unique ability is being able to place redline blocks (see Figure 6).

The linking feature performs an action when you click on a part of the drawing, such as display text, another drawing, or execute a script file. In addition, you can create these links with attributes defined in the drawing.

DRAWING Librarian Professional has a scripting language that lets you create mini-programs that are executed from the menu, with a keystroke, or by clicking a hot spot on a drawing. The software package comes with a number of applications written in its script language, such as comparing two drawings, converting drawings to PostScript, and search through a DWG for a specific text string. To access the DWG file directly, SoftSource has the extra cost DXE, a library of API and DDE routines.

DL for Windows is clearly a subset of the DOS version (see i figure 2). It only reads DWG and DXF files and only converts to BMP and WMF via the clipboard. It is limited to displaying a single drawing at a time and listing 100 block names. There is no redlining capability. Besides being low priced, DL for Windows' other strength is that it has DDE command names for all menu items.

Drawing Librarian Professional takes three seconds to load itself and another 39 seconds to load the Airport.dwg file, about 5.3 times faster than Release 12 DOS (combined times). DL for Windows takes five seconds to load itself but another 1:33 (min:sec) to load the Airport.dwg file, about 2.i times faster than AutoCAD LT (combined times).


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