(in)Compatibility between AutoCAD and Visio
Adam Stone
Comment: Reader Experience: Intermediate
A Visio user reports on his frustrations on getting an AutoCAD drawing into Visio 2000. While trying to figure out Visio's DWG import feature, Adam Stone found answers to his questions -- once he got to the right person at Microsoft.
I have always said, "I would never drive my car over a bridge that was engineered in Visio." On the other hand, I would never use AutoCAD do a simple floor plan layout. The point is to use the right tool for the job at hand. If you are a mechanical engineer or architect, AutoCAD may be the best tool for the job. On the other hand, if you are a space planner, interior designer, or system integrator, then Visio is the better tool to use.
Before going further, I should admit my bias toward Visio. I have never been able to draw more than a rectangle with AutoCAD, and even that took a week to learn. My only interest in AutoCAD is getting whatever drawing I need -- usually floor plans -- into Visio. Since most floor plans are done in AutoCAD, compatibility between the two software programs is a critical feature. Without this compatibility, Visio is just a Microsoft-friendly drawing package.
Importing Drawings in Visio 2000 With the release of Visio 2000 Technical Edition, I noticed some unusual issues cropping up with the DWG/DXF file converter. The first issue was the number of options and decisions needed to insert a CAD file. With Visio 5.0, it was a two-click process; with Visio 2000, I have many choices to address, all of them drastically affecting the final output of the drawing. Learn from my pain; follow the steps below to enlightenment:
Step 1. In Visio, set up the page size and scale to match the CAD drawing scale.
Step 2. From the Visio menu bar, select the Insert>CAD Drawing command, and browse to the location of the DWG or DXF file. (Note that Visio 2000 also reads IGES and MicroStation DGN files.)
Step 3. After you select the CAD drawing, Visio displays the CAD Drawing Properties dialog box. Set the CAD Drawing Scale to the scale the CAD drawing was created for. Don't worry about the box with the page and CAD drawing. I have not been able to find a correlation between the actual CAD drawing size and what is represented in the box.
For whatever reason, the default CAD Drawing Units are set to feet; I found it best to change the units to inches. In addition, uncheck the Lock Position and Lock Cropping.
The CAD Drawing Properties dialog box is displayed by Visio 2000
Step 4. Click the Apply button to "test" the conversion. If you get the dialog box shown below, it means that the scale you chose does not match the drawing. Go back and change the scale. Everything works better if they match. In particular, the scale of the two drawings should match when you plan to use Visio shapes on top of the AutoCAD drawing.
The CAD Scale dialog box warns that the scale of the CAD drawing does not match the scale of the Visio drawing
Step 5: Click the Layer tab, and adjust layers as needed; you can change the visibility, color, and line thickness of every layer.
Step 6: Click OK, and you should get a clean CAD drawing in Visio. Center the drawing on the page, and use the View>Layer Properties dialog box's Lock option to lock down the drawing, if desired.
When You Run Into Problems
In my experience, this process works about 80% of the time. The problem is what do you do with the other 20%? To my dismay, I found that currently there exists no online, offline, or any other support for AutoCAD incompatibility issues. The solutions in this article were gleaned from hours of tedious trial and error, and gentle prodding to get the folks at the Microsoft Business Tools Division to realize this was a serious issue.
The most common problem I have seen is when I follow the process above and everything looks great, but I get a cropped or blank drawing. This happens because the last person to use this drawing in the CAD application saved the drawing at a zoomed in view. Visio displays the last-saved view. Believe it or not, I was told by Microsoft that this was a "feature" that would be modified in a future release. The easiest way to solve this problem is to open the drawing in a DWG-compatible application (like AutoCAD or IntelliCAD), and use the Zoom Extents command to show the entire drawing; save the drawing. If you don't have AutoCAD or IntelliCAD, then ask the architect do this for you.
Another annoying issue is when I insert a drawing and all I get is a blank page, or just parts, of the drawing, such as the title bar or legend. At first, this looked to me like the problem above, but when I tried the zoom-to-extents solution, the drawing remained empty. I found out that the problem is caused by ObjectARX-defined entities, which are proprietary objects defined by AutoCAD programming code (commonly called "proxy objects"). Visio 2000 does not warn me that it cannot display proxy objects. The solution is to save the drawing in AutoCAD as an R12 DXF file. This converts the proxy objects into lines.
A similar issue crops up (pardon the pun) with AutoCAD drawings saved in "paper space" not "model space." Visio 2000 cannot display an AutoCAD drawing saved in paperspace (called "layout mode" in AutoCAD 2000). Bill Holt is in charge of DWG conversion for Microsoft. He told me that the only way to fix this is to use AutoCAD's Wblock command to export everything in paperspace to a new drawing file, then insert the new file and the original file into Visio to create a composite. (Paperspace and layout mode allow AutoCAD to display multiple 2D and 3D views in a single drawing for plotting purposes.)
The other major problem was not being able to change the color of layers. Visio allows me to change the color of layers in the AutoCAD drawing, but I found that this often did not work. I found out that the objects must be drawn in AutoCAD using color "Bylayer," which causes objects to take on the color of the layer. If objects are colored with the Color command, then the color cannot be overridden in Visio.
Helpful AutoCAD Cleanup Commands
I asked Bill Holt to provide me with a list of commands that I can use to help with problem drawings:
- Clean up drawing by using the Purge All and Audit commands.
- Use the ChProp command to select all entities and set color to BYLAYER. This allow the Visio user to change all the color of entities.
- Set Tilemode = 1 to put the drawing in modelspace.
- Set the view by using the Zoom Extents command.
- Save the drawing as a R14 DWG file. If the file has proxy objects (ObjectARX-defined entities) that are causing a problem, save as R12 DXF.
Special thanks to Bill Holt, Kelly Malone and Scott Campbell of the Microsoft Business Tools Division for putting up with my constant barrage of newbie AutoCAD questions. They are now clearly aware of all the issues and have promised to look further into solving these problems.