Hi, Jochen. Your suggestion sounds do-able; I'll play around with it and see 
if I can sort it out. I've got some digital calipers around here somewhere :) 
What I'm hearing is that the process of converting both the base map (and yes, 
I did create it in QGIS) and the parcel maps into PDF will distort the scale. 
(And that a print shop might compound the problem by manually fitting the 
source file to the printable area. Yes?) A question then is why didn't the PDF 
conversion distort them all the same way, to the same degree? The base maps are 
done now and I couldn't afford to do them again no matter what, so they are 
what they are. Going forward, is there an export option in Print Layout that 
will not distort the scale of the parcel maps?
I am so relieved that someone has an explanation for this!
- John A.
   ----- Forwarded Message ----- From: [email protected] 
<[email protected]>To: "[email protected]" 
<[email protected]>Sent: Thursday, May 27, 2021, 03:33:12 AM 
EDTSubject: Re: [Qgis-user] Did scale change outputting to PDF?
  Hi John, 
  as I understand it, you created the base map in QGIS. If you use the measure 
tool in QGIS to get the distance between two distinct features in the map (e.g. 
road intersections) and then measure the same distance on the printed base map 
with a ruler, it should be possible to calculate the scale. Maybe use two 
distances, one aligned more or less horizontally and one vertically, to check 
if the scaling is proportional. 
  As Andreas pointed out, it is probably a problem with the settings when the 
PDF was printed. In my experience it is a good idea to go to print shops 
usually working for architects and engineers since they are familiar with the 
importance of scaling (for advertising etc. it is more important that the whole 
content is printed, so that scaling might be used to fit the output to the 
printable area without potential cropping). You can print directly to a plotter 
in QGIS if you have access to the device, avoiding the PDF detour.
  
  EPSG 2264 should be fine. Units should be US feet.
  
  Regards
 Jochen
  
  
  Am 27.05.21 um 07:15 schrieb John Antkowiak:
  
  Hi. This plan was too simple to fail - but it failed. The charity whose 
project this is needed a large (that is... massive) paper wall map on which to 
plot and rethink its delivery driver assignments. Both drivers and delivery 
addresses are subject to change from week to week but it's not a pizza 
delivery; this is a regular run to supply people in a bad way. So the plan was 
to print the base map (roads and road names and county boundaries only) and 
then print 8.5 x 11 address maps with parcel data and orthos. That way, the 
base maps don't change but the physical parcel layer is flexible. (On top of 
that is a third paper layer indicating which drivers go where so someone can 
stand back and take in the whole picture graphically. Not a cutting-edge state 
of the digital art solution, but not everyone is cut out for that. It is what 
it is.) In order for this to work, the parcel maps have to be the same scale as 
the base map. Which they were... in QGIS. 
  We have to convert all the maps to PDF to print them, and we had to send the 
base map PDFs to FedEx/Kinkos to print the 9 map grid panels at 42" by 62" 
each.  
  When we got the big base maps up on the wall, we discovered the scale did not 
match the 8.5" x 11" parcel maps output to PDF and printed from home. It's not 
off by a lot, but it's enough to be painfully obvious from a single standard 
size sheet of paper. I don't know how to reverse engineer the big map scale 
precisely enough to enter a new scale number in the QGIS Print Layout. I didn't 
foresee it because this never would've been a conceivable scenario at the 
engineering firm where I picked up my meager GIS skills. (ArcMap sent a map 
directly to the plotter without interim steps.) There was no scale bar on the 
map. It shouldn't have been needed for this. 
  Did something happen to the map scale when QGIS output the map to PDF? Could 
the size of the image on the pdf page have been adjusted manually or otherwise 
when being sent to a plotter with 42" paper? Could the image have been 
distorted horizontally differently from vertically? For the life of me, I 
cannot trial-and-error guess at a scale to enter. I've gone through dozens of 
new 8.5" x 11" test maps trying to guess the correct scale. 
  Any ideas?  
  Thank you all - 
  John A.  
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