By Justin Doughty
Revit 2020 introduced the ability to import and use PDF files. The guide below goes through some of steps and things to look out for when using this feature in a typical workflow.
As with any process that requires scaling from another source, there may be some issues with accuracy. However these can always be corrected in the modelled elements afterwards.
Before you Start
It’s a good idea to first check the PDF, to make sure the size and scale are as expected.
Importing the PDF
In the Revit project go to the view that needs the PDF. Then go to Insert>Import>PDF. You can preview the PDF, check the page size, and select the Resolution in DPI. I would recommend to start with 150 DPI. The choice of DPI seems to be fixed in Revit and does not correlate to the DPI the PDF was created in. Once inserted, you can change or delete it from Insert>Manage Images.
Checking the Size
The First thing to do is select the PDF and Enable Snaps from the ribbon. You can then use Measure for a quick check, or Model/Detail Lines if a more permanent reference is needed. At the moment you cannot use Dimensions.
Before you insert the PDF I would recommend first setting the Revit View Scale to match that of the PDF, as it makes the workflow smoother.
However, you can always pick the PDF afterwards and change its scale in properties.
If you do not know the scale of the PDF and you have a known dimension for an object you can manually scale it, with the Modify>Scale (RE) command.
This lets you pick the PDF distance and then enter the known value.
To get started modelling, pick the PDF and check that Enable Snaps is on. You may also want to pin the PDF at this point to stop it moving around.
Then start placing walls using the snaps, make sure to choose the correct location line for the snaps so the wall is placed correctly on the inside/outside.
One of the advantages of this method, could be to utilise it alongside the mapping features of AutoCAD products. From AutoCAD, setup a site .dwg file, with aerial imagery, and then export to PDF. Then import this PDF in Revit: