Compare with another sheet

Puts this page against another and finds the areas where the two look different.

Why you would use it

Two jobs, one operation. The obvious one is revisions — what changed between rev C and rev D. The one nobody offers is comparing two DIFFERENT drawings of the same place: the structural sheet against the services sheet, to find where two disciplines disagree before somebody finds out on site.

For example

What to do

1. Open the sheet you want to check.
2. Choose the other PDF, and which of its pages to compare against.
3. If the other sheet sits differently on the paper, or is another size, choose to mark two points that are the same on both.
4. Walk the list. Each row takes you to that area on the drawing.
5. Cloud the ones that matter — they become ordinary revision clouds.

Going further

It compares the two sheets as PICTURES, so it finds anything that was drawn differently whether or not it means anything — a moved dimension string counts, a re-plotted title block counts. That’s why the result is a list of places to look rather than a report of what changed. Two sheets of different paper sizes are refused until you say how they line up, by marking the same two features on each; then the other sheet is moved, turned and, if you say the scales differ, resized to sit over this one. The two are drawn over each other in red (only here), blue (only there) and black (both). Nothing is altered on either drawing: the areas found aren’t markup, they aren’t exported, and they go when you close the panel.

If you already use another program

In a CAD program: Comparing two versions of a drawing.

In a PDF markup program: Overlay or compare two revisions: red where only this sheet has something, blue where only the other does.