I think that’s really a reply to @Fergos, isn’t it?
Mind you, it is not obvious to a layman why a pdf that seems to have very good screen resolution when viewed natively has such poor resolution when imported into SU. That may be the point @Fergos was really making.
can recommend PDF-XChange Editor. (Tracker software). been using it for years and very capable $50 i think and full featured and not subscription
You’re right. But at least I replied to your reply to him. 
A PDF that contains a .jpg or .png image is just that: a bitmap. It is entirely possible that a PDF contains a screen shot, which, by nature, is also a bitmap, dependent entirely on screen resolution at the time. For best resolution, render Layout viewports as vector whenever possible.
Does that answer the question, I wonder?
I could have a PDF open on my desktop which is just a line drawing with nice, crisp lines. I import it into SU and it looks like I should have gone to Specsavers (UK joke). So I can look at the same document on the same screen at the same time but the resolution will be very different.
My guess is that it is to do with the way SU handles image files. And right there my tech knowledge runs out!
Does it vectorize a line drawing?
Trademark is known here too.
When you import a vector PDF into the Mac version of SketchUp it gets rasterized (converted into an image). It might be that the resolution used is nothing to write home about.
Do you mean used by Apple or by me?
If this is a Mac thing, are you saying that the resolution of PDFs imported on a PC is much better?
No. The PC version of SU doesn’t import PDFs at all.
That makes me feel very much better!
Hi Simon,
Ahh, just realised your question was about PDF-EXchange, never used it for that… was not even thinking that was capable in any PDF editing software… let me check!
I can confirm to does OCR on text pretty well… (even OCRs Vietnamese characters successfully for me which allows me to google translate it) not sure what it does to the bitmap graphics, NUP, does not vectorise graphics… revert to software below…
Nup, DWG export / Import and Vector Tracing two popular requests on their very active forum… I have both Inkscape and Coreldraw that can do both !
I do a lot of wayfinding signage for my projects , AD is for doing accurate colour control [pantone], typeface setout for the sign contractors,
PS stumbled into this field 10 years ago, Architects are well placed for it as we have great understanding of the built environment, along with our graphic skills and with SU 3d visualisation… usually lacking in graphic designers or sign fabricators
The solution seems to update to 2021 - i.e. the problem is solved as far as I can understand.
Thanks again for all help and advice until this option appeared.
Fergos
Just piping up 4months later to say that all searches for this issue lead here, and there is no solution.
The issue still persists and the dev’s need to address it.