Revisions and comparison

The Revision feature visually compares a project's original PDF with a second PDF. It shows pixel differences sheet by sheet; it does not replace the source document or automatically migrate the takeoff.

Access and preparation

Path: project → Dashboard → Revision. An editor or project administrator uploads or removes the PDF; project members may view the comparison according to their role. Use a complete PDF and check its sheet order before upload.

Compare a revision

1. On the dashboard, select Upload a revision PDF and choose the newer version.
2. Wait for confirmation, then select Compare. The sheet selector opens active project sheets in numeric order.
3. Interpret the colours: red = ink only in the original, green = ink only in the revision, and grey = ink in both renders.
4. Use the zoom controls and inspect every changed area. Record the sheet, location, class and expected effect on counts, runs, areas or pricing.
5. Validate changes against the title block or addendum; colour indicates a graphical difference, not its contractual meaning.
6. Update the takeoff using the strategy below, then review the BOM, estimate and exports.

What comparison does—and does not do

Comparison renders both sheets as images and classifies ink. It therefore works with vector or scanned PDFs, but it does not semantically identify “device added,” “wall moved” or “note changed.” A slight offset, rotation, sheet-size, font or resolution change can colour much of the page.

Sheets are paired by position: sheet 1 to sheet 1, and so on. An inserted or removed sheet shifts later pairings. Disabled sheets are absent from the selector. A sheet present in only one PDF is compared against a blank page.

Most importantly, the revision PDF remains a separate comparison file. Project scale, detections, reference lines, runs and areas still belong to the original PDF. Comparison starts no detection, transfers no symbol and changes no count.

Apply changes and recover

For a few easy-to-locate changes, use comparison as a checklist and manually correct placements, statuses or recipes that remain meaningful on the source document. For a takeoff that must be geometrically based on the new PDF, create a new project with the revision as its primary document, then repeat scale, legend and review. Retain the previous project as the earlier-version record.

Uploading another PDF replaces the previous comparison revision and regenerates diff images. Remove revision removes the comparison link without touching the original PDF or takeoff. If colour covers almost everything, first check sheet order, dimensions and alignment instead of concluding that all content changed.