Sometimes there are instances in which you only want to compare a small area of two different drawing revisions. The most widely used features in Revu for comparing PDF drawings is Overlay Pages and Compare Documents, but these features are designed for comparing full size drawings, rather than a small area. So, what can you do? Use the Snapshot tool instead. The Snapshot tool is another great way to compare drawings, and gives you more flexibility and control when comparing small areas.
Note: When using Snapshot to compare a small area of a drawing, it's best to use two black and white drawings.
Open Drawing 1
Click the Snapshot button and draw a rectangle around the area that you want to compare.
Open Drawing 2
Press Ctrl + Shift + V to paste the Snapshot in the same location as Drawing 1.
Click the Change Color button in the Properties tab.
Click the Source Color button and then click the black color tile.
Click the To button and click the red color tile.
A second row of Source/To buttons will display.
Click the Source color button in the second column and click white.
Click the To color button in the second column and click no color, which is the white tile with the red slash though it.
Change the Opacity in the Properties tab to 60 or 70.
What I've done here is copy a Snapshot markup from one drawing, pasted it on the other in the exact same location, and then changed the color properties to visually compare the two. Lines and text that are the same in both drawings will display as a dark shade of red. Lines or text that are only in Drawing 1 will appear as a light red color, and lines or text that are only in Drawing 2 will be solid black.
Paste-in-place, Ctrl + Shift + V, used in the instructions above, allows you to paste the Snapshot in the same exact location as the original drawing. Alternately, if you use Paste, Ctrl + V, the Snapshot will paste at the cursor location, therefore Paste-in-place is recommended. If the two drawings are not aligned after using Paste-in-place, Snapshot allows you to make adjustments easily. Since a Snapshot is a markup, you can adjust the alignment of the two drawings by clicking on the Snapshot and dragging it to the correct location, or you can click on the yellow handles in the corners of the Snapshot to rescale it to the appropriate size.
Even though this example focuses on comparing a small section of a drawing, this process can also be used to compare an entire sheet.