AutoCAD introduced the DWG Compare command in version 2019 and at first glance, the command appears to have only gone through a “cosmetic” change in the AutoCAD 2020 release. In AutoCAD 2019 the command activated a complete Ribbon tab with multiple panels. In AutoCAD 2020 this has been replaced with a small DWG Compare fixed palette found just below the Ribbon.
Most of the same functions on the Ribbon panels can be found using the drop-down menu under the “Gear” icon on the new palette. This drop-down menu can be pinned in place if desired. The rest can be found on the palette itself with the addition of three function icons as shown by the red box.
I would like to first cover the major change to the DWG Compare command in AutoCAD 2020, which will help to explain the three new functions. In AutoCAD 2019, the command created a new comparison drawing from the two separate drawings you selected. It would use your current drawing as DWG 1 and you had to choose the second drawing for comparison which became DWG2. In the screen capture below, the current drawing was “Bank Class.dwg” used as DWG 1 and “Bank Class – Compare” as DWG 2. A new file tab, showing “Compare_Bank Cl…lass – Compare*”, was created to perform the comparison.
The DWG Compare command in AutoCAD 2020 uses the current drawing as the base drawing and places the comparison drawing into it as a special type of external reference. This means two things; an extra comparison drawing is not needed, and best of all, dynamic edits can be made directly in the current drawing during the drawing comparison process. This process can be used between the current drawing and a comparison with the same current drawing to create a unique revision control process which will keep track of drawing edits in real time. Once drawing edits are complete use the small green arrow on the DWG Compare palette to exit and then the current drawing saved.
The two other functions on the DWG Compare palette are:
This function allows you to select any object, which is marked as existing only in the comparison drawing and copy it into the current drawing. In my comparison, the Reception desk is in red showing that is only exists in the comparison drawing.
After using the Import Objects function, the desk is changed to a gray color showing it is now a part of both the current and the comparison drawings. Also notice that the Revision Cloud is removed.
The Light Bulb icon on the new DWG Compare palette is simply an on/off switch to activate the comparison or turn it off to make editing easier. As mentioned earlier, the Green Check icon quits the DWG Compare command.
I want to mention an AutoCAD system variable that makes the DWG Compare command much more useful during the command process. The system variable “COMPAREPROPS” can be set to the combined total of any of the following drawing property values so these properties will be detected during the comparison process.
0 – Object property changes are not included in the drawing comparison
1 – Color
2 – Layer
4 – Linetype
8 – Linetype Scale
16 – Lineweight
32 – Transparency
64 – Thickness
For example, to set the system variable to detect drawing comparison differences of “Color and Layer” the value would be set to 3. In my current drawing, the text layer and color, are different from the comparison drawing. With the system variable “COMPARPROPS” set to 0, the text is not flagged as being different.
With the system variable set to 3, both text values are marked as different between the drawings being compared.
The AutoCAD 2020 DWG Compare command has truly become a valuable tool in your design work.