Scaling Error - Print

[Former user]

I finished my first pattern in Valentina 0.3.0.0 and produced a layout by the new layouting algorithm. Then I saved as pdf. The chatch is, that somehow the file is not in scale (neither as pdf neither as png, neither with inch, nor with centimeters). I went to a professional printing agency and emphrasized that it had to be in scale but it wasn't. Then I tried everything thinkable at home and it didn't work. I also tried with only one pattern piece on A4 - but neither the view on my desktop (100%) nor printing it from different PCs and with different options worked. I just now installed Valentina 0.3.1.0 and it did not work, either.

[Roman Telezhynskyi]

Hi,

I will try help you, but first i need more information from you.

Then I saved as pdf. The chatch is, that somehow the file is not in scale (neither as pdf neither as png, neither with inch, nor with centimeters).

How do you measure distance? What programs do you use for print? What OS do you use?

I went to a professional printing agency and emphrasized that it had to be in scale but it wasn't. Then I tried everything thinkable at home and it didn't work.

But why just don't ask us instead? :) You, now, almost perfect bug reporter, because did all what you could do for fix it yourself.

Then I tried everything thinkable at home and it didn't work. I also tried with only one pattern piece on A4 - but neither the view on my desktop (100%) nor printing it from different PCs and with different options >worked.

Ok, it is close to what i want to know.

the view on my desktop (100%)

Did you measure image on screen? It will not work because your monitor has different dpi.

I just now installed Valentina 0.3.1.0 and it did not work, either.

This release contain only bug fixes for known issues.

[Roman Telezhynskyi]

one pattern piece on A4

Can you provide the file?

Second, do you know that all images Valentina create with 96 dpi. You should use this value when you print.
Third, i did not hear how big is measure mistake?
Fourth, some programs reduce image before print. You should disable such a option.

My patterns show measure error too, but on small distance there is no error. So error depend on ruller you use. You can also try this trick. Use only 1 cm or 1 inch, depend on what you use. Measure distance only by this 1 cm (inch). What result did you get? How big is difference from first measure?

In my case regular way measure show that line 2.5 mm smaller than i need. I second in 2.5 bigger than i need. :)

[Roman Telezhynskyi]

I'll try publish today packages for develop branch. In this version Valentina now support print.

[Former user]

Hello Roman,

Sorry for not answering - I thought that I would receive an email.

[quote]How do you measure distance? What programs do you use for print? What OS do you use?[/quote]

OS: Ubuntu 14.04 LTS and Mac OS X 10.7 with Valentina 0.3.0.0, 0.3.1.0, 0.3.2.0 and 0.3.2.1.

I measure distance in centimeters, but also tried in inch.

We printed with the build in document viewers on Mac OS X and Ubuntu (Document Viewer). Also, no special drivers. One problem is, that the printer is not allowing 96 DPI.

[quote]Did you measure image on screen? It will not work because your monitor has different dpi.[/quote]

I measured on screen and on paper, with different rulers. The Mac document viewer comes with a "original size"-function, which shows the document in exactly the size it will have on paper. E.g., if the printed thing is 5 cm long, it is exactly 5cm on screen. But I also printed about 20 sheets to measure it off screen with no result.

[quote]Can you provide the file?[/quote] https://www.dropbox.com/sh/yqkrtbvr9gle80s/AAB3ZpNFGOf8HJpp-wc2m9xMa?dl=0

[quote]Third, i did not hear how big is measure mistake?[/quote]

It's reproducable with every pattern, so, an example is linked to this message. The square should be 3 inches on every side, but if I export it as a pattern, it's approximately 2,8 inches - on screen and on paper. The mistake is getting bigger, when the part gets bigger. On 1 meter long parts I get a mistake of 5 centimeters.

[quote] Fourth, some programs reduce image before print. You should disable such a option. [/quote] As far as we found this options, they are disabled.

[quote] You can also try this trick. Use only 1 cm or 1 inch, depend on what you use. Measure distance only by this 1 cm (inch). What result did you get? How big is difference from first measure? In my case regular way measure show that line 2.5 mm smaller than i need. I second in 2.5 bigger than i need. [/quote]

Do you mean, that I should multiply all my formulas by a factor - eg. if it should print a line of 5 cm but prints 4,5 cm, then I should multiply the length of my line in valentina by 5/4,5?

Thanks for helping me! FB

[Susan Spencer]

I created a square of 10cm x 10cm. I created details with no seam allowance. Then created layout

A.) saved layout as PDF and printed. It came out as a 9.8cm x 9.8cm square The ratio of 10cm/9.8cm is 1.020408163

B) exported as PNG, opened in Inkscape, drew a square exactly on top of the image, and that square was 10.679cm x 10.679cm. This could related to the ratio of 96PPI/90PPI = 1.066666667. 10cm x 1.066666667 =~ 10.667. Difference could be accounted for by manual drawing error.

C) exported as SVG, opened in Inkscape, the square was 9.841cm x 9.841cm.
10/9.841 = 1.016156895 This is probably the actual size of case A) above, with the error in measurement due to eyeball error.

D) imported PNG into GIMP. Image is 96.012 PPI - I don't think this is useful information

E) Opened SVG in Inkscape, then imported the PNG. The PNG image is noticeably bigger than the SVG image. Confirms image size differences b/w SVG and PNG noted above.

[Roman Telezhynskyi]

Hi Ferdinand,

Sorry for not answering - I thought that I would receive an email.

You did not get email because created bug report as Anonymous.

[quote]

Use ">" character if you want create quoted text. I also long time did not know about this feature. :)

C) exported as SVG, opened in Inkscape, the square was 9.841cm x 9.841cm.

I made research and here what i found. Looks like my expressions are correct, but all formats we make from class QGraphicsScene. And this class make very strange things. In two vector formats i found wrong scale factor.

Examples:

SVG

<g fill="none" stroke="#000000" stroke-opacity="1" stroke-width="1" stroke-linecap="square" stroke-linejoin="bevel" transform="matrix(0.986587,0,0,0.986587,2.2373,2.2373)"
font-family="Arial" font-size="10.6667" font-weight="400" font-style="normal" 
>
<path vector-effect="none" fill-rule="evenodd" d="M778,9 L778,297 L490,297 L490,9 L778,9"/>
</g>

Take close look on transform="matrix(0.986587,0,0,0.986587,2.2373,2.2373). It has scale 0.986587!!!!

Normal group.

<g fill="none" stroke="#000000" stroke-opacity="1" stroke-width="1.51181" stroke-linecap="round" stroke-linejoin="round" transform="matrix(1,0,0,1,0,0)"
font-family="Arial" font-size="10.6667" font-weight="400" font-style="normal" 
>
</g> 

And we need 1!!

Same story for PDF(EPS and PS)

EPS

[0.954199 0 0 0.954199 2.163852 2.163852] cm

I fixed matrix in SVG file and value became 3,010 inch (expected 3 inch)!!!

And i think same will true for PNG.

We can ask Qt developers why this happens and try set for all object transformation matrix manually (scale to 1).

[Roman Telezhynskyi]

I think, i have found my mistake. Wait my patch.

[Roman Telezhynskyi]

Fixed issue #297. Scaling Error - Print.

→ <<cset 5c0aeb889bb3>>

[Roman Telezhynskyi]

Fixed issue #297. Scaling Error - Print.

→ <<cset 19d49f9e3b33>>