Pixel overlay aligns two whole sheets and flags every pixel that differs — which is why a moved view or a resized sheet buries you in false red. Revisic works one level up: you tell it which sheets and views correspond across revisions — a couple of clicks — and it aligns them automatically and compares what's drawn inside. Here's the whole pipeline.
The gap that view-level comparison exists to close.
A pixel overlay treats each sheet as a flat image: it stacks the old and new sheet and colours any pixel that doesn't match. That's perfect for a markup round where everything stays put. But a real revision often moves things — a detail slides across the sheet, a view jumps to another sheet, the whole sheet is reissued at a larger format. To the overlay, a view that moved 50 mm is 100% different in its old spot and 100% different in its new spot. The genuine edits — a changed dimension, a deleted bolt — are lost in a page of red. Revisic removes that motion before it ever compares anything.
Each stage strips out one kind of false difference, so what's left at the end is the change that actually matters.
Revisic reads every sheet in both revisions and lays them out side by side. You pair them up — old S-04 to its new counterpart, even if the set was reordered or the sheet was renumbered. A few clicks, and it's what stops you from diffing two unrelated sheets.
A view changed position, or moved to a different sheet entirely? Mark it once — point at it in the old revision and in the new one — and Revisic treats it as the same view from then on, instead of flagging it as deleted in one place and added in another.
Each matched pair of views is registered onto the same frame of reference: Revisic finds shared geometry in both and computes the transform — shift, rotation, scale — that lays one exactly over the other. A sheet reissued from A1 to A0 is absorbed here.
With the views aligned, Revisic compares what's actually drawn and highlights the real differences — added, removed and changed geometry — inside each view. The output is a side-by-side report you can read and export.
This is the part that older tools leave to you — clicking matching corners by hand. Revisic does it automatically.
Revisic scans both views for distinctive features — corners, intersections, recognisable bits of linework — and finds the ones that appear in both. Those shared features act like landmarks: once enough of them are matched, there's exactly one way to shift, rotate and scale one view so its landmarks fall on the other's. Revisic computes that transform and applies it, then ignores any matches that don't fit the consensus, so a few stray marks don't throw the alignment off. The result is two views in perfect register — and only then does it look for differences. Competing tools that rely on you placing manual reference points are doing this same job by hand; here it's automatic.
Knowing the boundary is what makes the output trustworthy.
Revisic compares what's drawn on the page. It doesn't read intent or grade severity — it shows every geometric difference and leaves the engineering call to you.
Works best on vector PDFs exported from CAD/BIM. Scans work too, but a skewed or low-quality scan adds noise to the alignment and the diff.
When in doubt it shows more rather than hiding something important. It speeds up your review; it isn't a substitute for it, and you remain responsible for the drawings you stamp.
Drop two PDFs, or load the sample pair with a resized sheet. No account, files auto-deleted.