How to compare two PDF drawings

Open the new revision, point Stamppa at the old one, and the differences appear on the sheet. Nothing is written to your file until you decide to turn the changes into clouds.

Compare a revision on the sheet

Open the new revision of the drawing.
Choose Review ▸ Compare with older revision…. Pick the older revision from another open tab, or choose a file.
In the options box, leave Compare the drawing checked, and check Compare text if you also want the words (see below). Click Compare.
Stamppa pairs the pages by sheet number and paints the differences over the sheet in two colors: what only the older revision has (removed) and what only this one has (added).

The compare bar

A small bar floats at the bottom of the page view while a comparison is open.

The eye shows or hides the differences on the sheet.
The colors menu chooses which changes are drawn (only the older revision’s, only this one’s, or both) and lets you change their colors.
The slider sets how strongly the comparison is drawn over the sheet. At 0 only the sheet shows.
Previous change and Next change take you from one change to the next, with a count beside them.
The cloud button, and its arrow, turn this sheet’s changes into revision clouds, or every sheet’s, in one undo step.
Export comparison… saves a PDF with the two revisions laid over each other.
Close the comparison puts the sheet back as it was.

Turn the changes into revision clouds

Step through the changes with Next change and check them.
Click the cloud button for this sheet, or open its arrow and choose Turn every sheet’s changes into clouds.
The clouds are ordinary markups. They show in the Markups list (Ctrl+L) and in any PDF viewer. If they are not what you wanted, undo with Ctrl+Z: it takes them all back in one step.

Compare the text

In the options box, check Compare text. Ignore capitals treats “NOTE” and “Note” as the same word. Extra spaces and line breaks are always ignored.
Stamppa lists the words added, removed, changed or moved, page by page, with a report. A scanned drawing has no text to compare; run Recognize text (OCR) on it first.

Compare a whole set

Choose Tools ▸ Run a tool ▸ Compare a set….
In the window that opens, pick the old issue and the new issue of the set. Stamppa pairs the sheets by sheet number and shows the pairs so you can correct them.
Run it. Stamppa compares every sheet and writes a Set compare report as PDF and CSV. It also carries your markups from the old set onto copies of the new files. Your originals are not changed.

Replace a sheet and keep the markups

Open the set you have marked up.
Choose Review ▸ Slip-sheet a new revision… and pick the new revision’s file.
Stamppa replaces the sheets by sheet number and keeps every markup. Sheets that are new are added at the end. If it finds no sheet numbers in the new file, the pages replace the old ones in order.

Tips

Clouds from a comparison mark where something changed, not whether it matters. Review them before you send them on.
Pages pair by sheet number, so a reordered set still compares sheet to sheet.
The comparison is a view. Close it and the file is as it was, unless you made clouds.