Placed PDF has raterized vector lines

[moovme]

Does anyone happen know why a PDF document I saved out from CAD has come into AF Publisher with all the vector lines being rasterized? I have placed it in using the PDF Passthrough: Passthrough.

[lacerto]

There are several reasons why this may happen. The most common explanation is that Affinity passthrough compatibility rule for PDF placement has been violated. The internal Preflight tool should inform if this happens, but basically it happens (and rasterization follows) if the PDF version number of the placed PDF is greater than version number in which the PDF is exported. Also, if you export using PDF/X-based method, all PDF files placed to be passed through need to be created using a PDF/X method (but note that exporting PDFs created using PDF/X-1a method, may still be rasterized if exported using PDF/X-1a).

The most compatible export method is using the default "PDF (press ready)", which should be able to pass through any placed PDF file (but note that it does not flatten transparencies). If you need to produce PDFs with flattened transparencies, you have to use PDF/X-1a, or PDF/X-3 to avoid rasterization. The latter is more compatible, but still requires placed PDFs to be produced using PDF/X-1a or PDF/X-3 to retain vectors as vectors.

If it seems that you are in dead end, try placing the PDFs using "Interpretation", as that will typically retain vectors, but then you should be careful to see that placed content is correctly interpreted, including colors and fonts.