How are PDF drawing revisions compared?
The tool rasterizes a selected page pair at a bounded resolution, supports visual overlay modes, and uses two corresponding point pairs to solve translation, uniform scale and rotation before pixel differences are displayed.
How to use the PDF Drawing Comparison
- Step 1Load old and revised PDFs and choose the corresponding pages.
- Step 2Align matching reference points when sheets have shifted, scaled or rotated.
- Step 3Inspect overlay, swipe, red/cyan or thresholded visual differences and export PNG.
Formula / How it works
Two corresponding point pairs determine translation, uniform scale and rotation for visual alignment.
Example
Align two drawing revisions by matching two points, then inspect thresholded visual differences.
PDF Drawing Comparison FAQ
Does Difference mode understand drawing objects?
No. It compares rendered pixels and may include anti-aliasing differences; it is not semantic or AI comparison.
Why is alignment important?
A small shift or scale change can make every pixel appear different even when the underlying content is unchanged.
Are source files uploaded?
No. PDF rendering, alignment and comparison remain in the active browser session.
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