The cloud shows what the designer chose to mark
A revision cloud is drawn by hand. A shifted grid line, a moved door or a deleted dimension outside the cloud is found in the field, when something no longer fits.
Drawing revisions
Compare drawing revisions: overlay two sheets and see what changed
When a new revision of a sheet arrives, the team needs to know what actually changed before anyone builds from it or prices it. In Fidrel you open the two revisions together and lay them over each other: lines only in the older sheet turn red, lines only in the newer turn blue, and what stayed the same is grey. If you would rather read than scan, you view the two sheets side by side.
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Why changes between revisions get missed
Two windows, one pair of eyes
Flipping between two PDFs means holding the first sheet in your head. On a dense floor plan a door moved a few inches slips through, and the review takes an hour for a revision that changed one wall.
The change reaches the crew unannounced
When a new revision is uploaded without anyone naming what changed, the crew keeps building from the version they know. The cost shows up later as rework and an argument about who had which sheet.
What the colors mean
Fidrel draws both sheets at the same scale and compares them dot by dot. Ink that exists only in the older revision is red, ink that exists only in the newer revision is blue, ink in both is grey and the paper stays white. A wall that moved therefore shows twice, in red where it was and in blue where it is now. The key above the sheet names the files, for example Only in the older and Only in the newer. Fidrel treats the earlier upload as the older revision and the other as the newer one, so the colors do not flip when you swap the panes.
Documents, drawings & models
From a difference to a decision
An overlay tells you where to look, not what to do. A difference that needs an answer becomes an RFI; Fidrel can start one from a markup on the drawing, and it warns on an RFI when the drawing has a newer revision than the one the RFI was raised on. If the answer changes scope or cost, a change order can be started from the RFI. Quantities and prices that depend on the sheet are rechecked in the estimate by hand.
How to compare two revisions of a drawing in Fidrel
Step 1
Upload the new revision under its number
Upload the sheet. Fidrel reads the number from the file name and adds the file as a new version of that drawing, skips a file identical to the current one, and lets you write a Change note for the new version.
Step 2
Open both revisions side by side
Open the newer revision in the viewer and the older one in a second tab, then choose Show side by side and pick the older sheet in the list under File on the right.
Step 3
Choose Overlay
When both sheets are PDFs or both are images, an Overlay button appears in the header of the right-hand sheet. Fidrel lays the older revision under the newer one and colors what only one of them contains.
Step 4
Page through and decide
On a multi-page PDF use Previous page and Next page. A page without changes says No differences on this page. Switch back with Side by side, then raise an RFI or a change order, or recheck the estimate.
Earlier revisions stay available
Every upload is kept in the version history with its revision, its date and the change note that came with it. The drawing register lists the current revision of each sheet with its number, title, status and revision date, can show all revisions, and marks the earlier ones as superseded. Comparing is therefore possible for as long as both files are in the project, with no need to dig through e-mail for the old PDF.
What the comparison does not do
The overlay works on two PDFs or two images only, so DWG and other CAD sheets cannot be laid over each other. Fidrel colors the differences but does not list them, number them or say what a change means. The overlay is a picture drawn in your browser from the two files, not a verified or pixel-exact comparison, and very pale lines are not counted as ink. Both sheets are lined up at their top left corner, so a revision that was re-framed shows as changed everywhere. To compare two CAD revisions, export both to PDF first and upload the PDFs.
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Drawing revisions
Frequently asked questions
Anything else on your mind? We are happy to help.
Talk to usNot as an overlay. A DWG sheet can be opened and viewed in Fidrel, but only two PDFs or two images can be laid over each other. Export both CAD revisions to PDF and upload them to compare.
The one uploaded earlier. If Fidrel cannot tell the two upload dates apart, it takes the file you opened first as the older one.
No. It colors the differences on the sheet and tells you when a page has none, but it does not list, number or describe the changes. You read the colors and decide what each one means.
Yes, if the scans are images or PDFs. Because the sheets are lined up at their top left corner, two scans that were squared differently will show lines as changed that did not change.
No. An overlay compares two files at a time, so compare the newest with the previous one, then the previous with the one before it.
In the Version history of the drawing and in the drawing register when you choose All revisions. The register marks earlier revisions as superseded and keeps them.