Version Compare: A simple polyline example

As mentioned in an earlier blog posting, Version Compare of Autodesk Design Review 2008 is very precise when it comes to comparing lines in a DWF file. It detects all of the changes except for line color. I decided to conduct a simple test.

1. 
   I created a DWF file with 9 polylines. I inserted text next to each line to describe what change I was going to make to each polyline. I used AutoCAD 2007 to create the original version of this file.
   Download dwf_compare_lines_original.dwf (3.8K)

2. 
   I made a copy of the original DWF file. I converted the DWF file to ASCII using the unpack utility, so I could make simple changes using a text editor. I modified the file:

   1. No difference - This is a control point or baseline. No changes were made.
   2. Point added - The 5 point polyline became a 6 point polyline with the addition of another point at the end.
   3. Point deleted - The 5 point polyline became a 4 point polyline with the removal of the point at the end.
   4. Point changed - The 5 point polyline remained a 5 point polyline but had the coordinates of its last point moved up and to the right.
   5. Color (not detected) - No changes were made to the points. Only the line color has changed from black to purple.
   6. Pattern - No changes were made to the points. Only the line pattern was changed from solid to dashed.
   7. End Cap - No changes were made to the points. Only the line end cap was changed from rounded to butt .
   8. Join - No changes were made to the points. Only the line join style was changed from rounded to miter .
   9. Weight - No changes were made to the points. Only the line weight was changed from 2488 DWF units to 3488 DWF units.
   
   Download dwf_compare_lines_modified.dwf (3.8K)
   Like the original, this too is an ASCII DWF file that can be examined using a text editor such as Notepad.
    

3. 
   While viewing the original DWF file, I invoked Version Compare from the Tools menu.

4. 
   The Version Compare dialog allowed me to pick the modified DWF file as my second DWF file. Once the file was selected, it showed me the list of sheets in this file. In this case, there was only one sheet. I selected that sheet. Note that the dialog does alert users that Warning: Not all drawing changes are included in Compare. For details, please search for "Compare" in the help file. We want users to be aware of the 3D, image, fill pattern, and color limitations.
   
   The compare dialog has an Options button where you can select colors.
   
   
   
   By default, just like what Autodesk Architecture does for DWG comparisons, Additions are green and deletions are red. For this example, I wanted to highlight the additions, so I selected red for my Additions color. In deference to those who are red/green color blind, I selected blue for my Deletions color.

5. 
   After clicking OK from the Version Compare dialog, Autodesk Design Review created two markup items for me. The Additions markup item shows what needs to the original DWF to make it match the modified DWF. The Deletions markup item shows what needs to be removed from the original DWF to make it match the modified DWF. As mentioned in the previous posting, the Version Compare feature cannot detect differences as changes. In this example, 8 of the 9 polylines changed. Version Compare detects 7 of these changes - all except color. So the 7 polylines show up once as added and again as deleted. You can see that the No changes and Color polylines are the only two that Version Compare identifies as unchanged.

6. 
   When an object changes by moving, the change is easy to see. It shows up once in red as added and again in blue as deleted. Due to the movement, these items can be seen side by side. In our case, we have the original black polyline, the added red polyline, and the deleted blue polyline all on top of each other. You can bring the added (red) polyline to the forefront by selecting the Additions markup item. For the line pattern change case, you can see the parts of the solid blue Deletions polyline in the spaces left by the dashed red Additions polyline. Autodesk Design Review also shows a lasso around the region that bounds the extent of the differences included in that markup.

7. 
   The same is true for deletions. You can bring the deleted (blue) polyline to the forefront by selecting the Deletions markup item. Autodesk Design Review shows a lasso around the region that bounds the extent of the differences included in that markup.

By applying pen styles in AutoCAD, most architectural drawings have a variety of line styles based on pattern and weight. These styles are applied as part of publishing a DWF file and appear in the DWF file. The Version Compare feature detects these differences to alert users as to what these changes represent such as what was once a gas line is now a sewer line. This type of electronic processing is another reason DWF goes beyond the paper.