How do I get dashed lines to show dashed in PDF?

[CerpherJoe]

Hello,

I have completed a drawing at 1:20 (1" = 20') scale with some dashed lines. I notice in the drawing itself you can toggle 'Screen-based Linetypes'. I have them toggled on and the dashed lines show up fine in Print Preview. However, they disappear when exporting to PDF. I have other test drawings (using various drawing units, but same 1:20 scale) where the dashed lines have printed fine in PDF.

Any ideas?

Thanks!

[Husky]

Hi,

there are three styles of dashed lines - do you have the same issue with each of them?

I have completed a drawing at 1:20 (1" = 20')

Something doesn't ends up with this scale statement
1:20 is not 1"=20'
Please doublecheck and tell me which one is used so that I can try to reproduce the issue on my end. BTW: A posted example drawing would make it easier for us to look into the issue ...

[CerpherJoe]

Of course - you are right! Used 1:240 scale.

The dashed line I am using is 'ISO Long-dash double-dot'.

I see many dashed line choices from the Layer->Linetype dropdown.

Jefferson Street NE LT2181778.pdf

(108.38 KiB) Downloaded 562 times

Jefferson Street NE LT2181778.dxf

(188.46 KiB) Downloaded 537 times

[Husky]

The dashed line I am using is 'ISO Long-dash double-dot'.

I used the layer "Plat" which has that line type. PDF and paper print looks good to me. Is your print differed?

Husky-2019.05.27-01.png (1.83 KiB) Viewed 7190 times

[CerpherJoe]

Thanks. No, I'm still having the problem.

Here's from the PDF:

Dashed lines problem.png (1.43 KiB) Viewed 7177 times

Here's from QCAD:

Dashed lines problem b.png (1.04 KiB) Viewed 7177 times

[Husky]

Please try to open this pdf with a different pdf reader to see what happens.


Edit:
This is my test pdf produced by QCAD. Looks and prints just fine on my system.

test.pdf

(3.61 KiB) Downloaded 489 times

[johan162]

This is something I have also found a bit confusing. The following is perhaps not so much a direct answer but some insights (or lack of ...) in regards to line-type scaling.

My understanding of how it is supposed to work is illustrated below with a simple centerline pattern and how it appears in model-space, print-space and print-space and cahnges depending on viewport setting and linetype-scale setting. All images scaled to the same apparent screen size (roughly).

If we start with a linetype-scale of 1 (default) the model space looks like this.

linetypes-modelspace.png (4.8 KiB) Viewed 7052 times

If we view this with "Screenbased-linetypes" it is almost the same

linetypes-modelspace-screenbased.png (5.76 KiB) Viewed 7052 times

If we then disable sceenbased-linetypes and put this in the paper-space in both a 1:1 and a 1:4 scale it will look like below

linetypes-NOT-scalewithviewport.png (11.19 KiB) Viewed 7052 times

Exported to PDF this will look like this

linetypes-NOT-scalewithviewport-printpdf.png (18.03 KiB) Viewed 7052 times

If we instead repeat the previous exercise but with the option "Scale of linetypes matches the scale of the viewport" checked (Preferences->General->Linetypes) we get the following (the model space is not affected by this!)

Paper-space:

linetypes-scalewithviewport.png (11.21 KiB) Viewed 7052 times

As we can see the 1:1 viewport is the same but the 1:4 viewport has been adjusted. In PDF it looks like expected

linetypes-scalewithviewport-printpdf.png (13.8 KiB) Viewed 7052 times

Changing the linetype-scale
In prints I prefer to have more tight lines so I usually apply a factor to the linetype scale and here things become interesting. The model space and print space does seem to start behaving in what might seem different ways. If we apply a 1/10 scale factor (0.1) the result is as follows:

First the model space

linetypes-modelspace-0.1-scale.png (5.38 KiB) Viewed 7052 times

With this scaling we are no longer able to see the individual gaps in the line. However ...the paper space looks as expected

linetypes-NOT-scalewithviewport-0.1-scale.png (11.16 KiB) Viewed 7052 times

whish is also reflected in the resulting PDF

linetypes-NOT-scalewithviewport-0.1-scale-printpdf.png (18.49 KiB) Viewed 7052 times

If we now again check the "Scale of linetypes matches the scale of the viewport" The paper space will become

linetypes-scalewithviewport-0.1-scale.png (11.07 KiB) Viewed 7052 times

This result is unexpected. With the default linetype scaling of 1 the (1:4) scale in the previous example got a bit denser (don't think it was four times though) bu he we actually get a less denser line! Which I cannot quite explain. My understanding of viewport scaling of linetypes is that the should follow the scale to appear the same in absolute appearance which clearly is a wrong understanding o my part..

My understanding was that the dashed lines should follow ISO absolute lengths However the above experiment shows this not quite to be the case since the model-space and print-space with the same 1:1 scale shows different density for the dashed lines. The print space (for center-line) shows a gap of 20mm while the model space shows a gap of ~0.6mm .

I'm sure I must have misunderstood something and since I can always workaround by manually setting a linetype-scale (to get the proper ISO spacing in the final PDF output I've just put this as on of life's (many) mysteries!