CAD Drawing Redlines
CAD redline markups are a process of annotating a drawing to indicate an error or suggest an amendment. There are two main triggers for redline markups.
Project revisions: When a drawing is in the project/construction phase, a drawing will often undergo a number of revisions before it is finalised with an as-built status. Redlines provide a convenient method for drawing reviewers to suggest changes on a drawing.
Operations and maintenance: Sometimes during on-site surveys, or during the course of general maintenance work, errors can be discovered in drawings. These can be highlighted using a redline markup, which will then trigger a revision update on the drawing to correct the issue.
When drawings are uploaded to Lunr, a few files are generated in the background:
A thumbnail to support quick previews.
A PDF rendition to enable viewing in the browser and redline markups.
An OCR content file to allow users to search for text inside drawings.
Markups are stored against the PDF rendition, allowing for easy review on the web. Securities can be used to control which users can view and create redline markups. Commonly, read-only users will not have access to redline markups, instead only seeing the latest as-constructed drawing file.
When drawings are released from document workflow, markups are kept with the current document version, meaning the new as-constructed version does not include the markups from the previous version.
