Scale in pdfs slightly wrong

[jackieh]

I am trying to print out part of a drawing at a specific scale (1:50) exporting to pdf format and printing on A4. Everything looks about right, but when I measure it to check, everything is slightly wrong e.g. a measurement that should be 1.69m is 1.60m and so on.

Please help!

[hungerburg]

When you print 1:50 and the original is 1.69m then the print should be 3,38 cm; if it was 1.60m it would be 3.20 cm - so you have a deviation of 1.8 mm; that is fairly small, in my view, not noticeable with the eye, if both lines are not close to one another.

I have one idea, why lines would be longer on the print: QCAD exports lines with PDF line cap "butt", i.e. rounded endings, which looks nice on corners e.g. because they meet very well. Yet, the butt extends beyond the very extension of the line and makes it a little longer (same as the width of the stroke); the more, the thicker the line gets drawn, whatever the length of the line, same absolute amount added!

But in your case, its the opposite - They get shorter! To check, maybe draw two lines 10cm apart, then measure the distance between the middle of each of both lines: horizontal ones and vertical ones. You may of course also try that with a different printer, you did not name, what you are using, or with another paper or some film instead, this all adds measurable diversion in prints.

Opening a QCAD exported PDF in a pdf-editor indeed shows the exact expected measurement, when lines are converted to hairlines, that is.

[jackieh]

Thanks. I shall continue experimenting. Unfortunately, for a buildings archaeologist (me) that sort of deviation isn't acceptable, since I need to be able to take plans/elevations to site and add, correct and amend from the actual buildings. I don't just use the drawings for presentation purposes.

The printer is a laser printer (HP CM1312) and I've used both it and the paper to produce scaled drawings before using another programme (which I can no longer afford!)

[Husky]

Hello jackieh,

please double check your pdf program printer settings. You will see a couple of "Page sizing" options. Make sure you have checked something like "Actual size".

Husky-2015.08.07-01.png (59.84 KiB) Viewed 11272 times

My pdf printings are absolute precisely scaled. A 1.69 m line is readable as a 1.69 m line with a 1:50 scale ruler (triangle ruler) ...

[jackieh]

Stranger and stranger...today the measurements are correct (not sure if that's because of checking actual fit was ticked or not, as I'm pretty sure that's how it was last week), but now there are clear distortions as well, and some unwanted lines. In fact, they were there last week, but because my print area has moved slightly, they were not so visible. These are visible on screen in the pdf and not just a product of printing.

Printing the document directly works, is undistorted and to scale; saving as an XPS file and then printing it is undistorted but not to (correct) scale. Any further thoughts would be appreciated, especially regarding pdfs, as I could do with a stable and commonly used format for sharing, printing and archiving.

Thanks, Jackie

[Husky]

Hello Jackie

Stranger and stranger...today the measurements are correct (not sure if that's because of checking actual fit was ticked or not, as I'm pretty sure that's how it was last week), but now there are clear distortions as well, and some unwanted lines. In fact, they were there last week, but because my print area has moved slightly, they were not so visible. These are visible on screen in the pdf and not just a product of printing.

Please attach a test drawing with a note what isn't working between the QCAD drawing and the QCAD pdf output. Thank you.

Printing the document directly works, is undistorted and to scale; saving as an XPS file and then printing it is undistorted but not to (correct) scale. Any further thoughts would be appreciated, especially regarding pdfs, as I could do with a stable and commonly used format for sharing, printing and archiving.

Sorry but we can't help you with any XPS files - that isn't supported by QCAD. Maybe you should ask the MS Support ...

[jackieh]

Print screen 11-08-2015.docx

Screen shot, terrible resolution, but with parallel parallel lines!

(153.83 KiB) Downloaded 522 times

KC 5 11-08-15.pdf

Pdf with converging parallel lines

(5.73 KiB) Downloaded 522 times

Thanks very much again. I have attached a pdf file and a screen view pasted into a word document, for comparison. I'm afraid the resolution on the print screen is terrible, but you can still see the distortion (in the pdf) on the right hand side, where parallel lines are converging.

[Husky]

For comparison between the QCAD pdf and the QCAD dwg I need to see both file types. Now I have the pdf but the dwg (dxf?) is still missing.

Please attach the regarding dwg to this thread or send it to me via PM. Thank you.

[jackieh]

Survey with Sept 14 corrections 17-08-15.dxf

(1.92 MiB) Downloaded 516 times

Sorry about the delay (I've been doing site work), and thanks for your continued help. I've attached the dxf file. It's of a large area, so I've ID'd the area I sent the pdf of using a red box. Hope you can see the difference between the two, especially the converging lines on the rhs of the pdf. Looking forward to your reply in due course.

Thanks again, Jackie

[andrew]

I've exported the marked area (scale 1:50) to PDF using File > PDF Export and attached the result (latest QCAD 3.9.8). This seems to look fine.
What's your QCAD version and what exact Windows version are you using?

[jackieh]

Thanks Andrew (and sorry again for the delay in replying - more site work). I'm really glad that you've succeeded in getting the pdf correct - it shows there must be a solution! I'm working on with windows 8.1, Adobe Reader 11.0.11 and QCAD version 3.9. Hopefully, this is something simple, and I'm looking forward to your next post.

Jackie

[andrew]

What I was trying to say is that everything works exactly as expected here and if you are also using the latest version of QCAD (3.9.8) it should work just fine for you as well.

[jackieh]

No, strangely, I'm still getting a lot of convergence (of parallel lines) and gaps where there shouldn't be gaps. I'm really struggling to think what might be the problem here, and how to solve it. Once again, the errors are visible on screen in the pdf. Luckily, the print button works fine, so I can directly print stuff out to take to site, but it'll be trickier to produce something to share or put in a report.

Any help greatly appreciated. Back in office in a couple of days.

Jackie

[andrew]

What is the complete version number of the QCAD version you are using? 3.9.8 or 3.9.7, 3.9.6, etc? Thanks.

[jackieh]

Sorry to be dim here, but I can't seem to find that information. Where should I look?