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sscott100
Participant
November 30, 2018
Answered

Important line thickness issue with engineering plans

  • November 30, 2018
  • 3 replies
  • 5125 views

The issue that my organization is having is that 11"x17" PDFs do not always show up visually correct on a standard widescreen computer monitor using Adobe Acrobat Pro DC. As you can see in my screen clips below the lines do not appear to be the same thickness when zoomed out vs when zoomed in. The first clip is zoomed out to full page and you can notice that the text looks strange and that the dashed lines appear to all be the same thickness. The second clip is zoomed in 300% and you can finally start to tell the difference in the dashed lines and the text looks more normal. These clips are from a plan set that was created using Autodesk Civil 3D 2018 and plotted using the DWG to PDF option. Note that when printed, the line thickness shows up correctly.

I believe that this is a very important issue because organizations, including government agencies, are reviewing complex engineering plan sets on their computers rather than printing the plan set out. This is becoming almost the standard because it is convenient, cost effective, and eco-friendly (saving the trees). So what is happening is that the reviewers are sending plan sets back because some of the graphical line work does not show up properly and they think that it is an issue on the designers end when in reality it is because Adobe Acrobat DC does not show these lines correctly. Note that zooming in can make the plan set much more difficult to review.

What is needed is for the plan sets to look on the computer screen exactly as it looks when printed out. My question is, has Adobe addressed this issue at all and/or are they working on a permanent fix? And in the meantime are there any tools currently available to manually fix this issue?

This topic has been closed for replies.
Correct answer Dov Isaacs

Some further explanation since I believe there are two issues at play here.

There is absolutely nothing that Adobe can do unconditionally bridge the difference between how a very thin line looks on a 600dpi or 1200dpi printer versus a computer screen that is typically 120 to 150dpi or possibly as much as 300dpi (such as with 4K monitors). And CAD programs often allow specification of very thin lines (sometimes 0.1pt in width). Acrobat/Reader does provide the “enhance thin lines” feature, but sometimes that backfires because depending on the content itself, you end up with overly thick lines. Depending on the content, you may need (or want) to toggle that option on or off to suit the needs of the document being viewed at a particular magnification.

This problem is further aggravated by applications, such as some of the Autodesk applications that instead of providing character output using text, actually use text outlining or even just strokes to represent the characters. This is a very poor practice. Why? When text is output using fonts, the renderer optimizes display based on the target device's actual resolution and the text's point size / magnification using the fonts' internal “hinting” mechanism. When rendering text via vector strokes, such “hinting” is unavailable and lines might be either too thin or too thick and may be either improved or degraded using the “enhance thin lines” feature. (In the sample provided by the OP, it would appear that the text is indeed simply vector stroking!)

Solutions? Obviously, part of the solution is for the PDF creator to generate PDF in a manner such that text is rendered as text. But the other issue is really a matter for the content creator. If the content creator knows that the content will be both viewed and printed, it would be prudent to use line thicknesses and spacing in dashed lines that would be reasonably viewed on both screen and for print.

          - Dov

3 replies

Dov Isaacs
Dov IsaacsCorrect answer
Legend
December 5, 2018

Some further explanation since I believe there are two issues at play here.

There is absolutely nothing that Adobe can do unconditionally bridge the difference between how a very thin line looks on a 600dpi or 1200dpi printer versus a computer screen that is typically 120 to 150dpi or possibly as much as 300dpi (such as with 4K monitors). And CAD programs often allow specification of very thin lines (sometimes 0.1pt in width). Acrobat/Reader does provide the “enhance thin lines” feature, but sometimes that backfires because depending on the content itself, you end up with overly thick lines. Depending on the content, you may need (or want) to toggle that option on or off to suit the needs of the document being viewed at a particular magnification.

This problem is further aggravated by applications, such as some of the Autodesk applications that instead of providing character output using text, actually use text outlining or even just strokes to represent the characters. This is a very poor practice. Why? When text is output using fonts, the renderer optimizes display based on the target device's actual resolution and the text's point size / magnification using the fonts' internal “hinting” mechanism. When rendering text via vector strokes, such “hinting” is unavailable and lines might be either too thin or too thick and may be either improved or degraded using the “enhance thin lines” feature. (In the sample provided by the OP, it would appear that the text is indeed simply vector stroking!)

Solutions? Obviously, part of the solution is for the PDF creator to generate PDF in a manner such that text is rendered as text. But the other issue is really a matter for the content creator. If the content creator knows that the content will be both viewed and printed, it would be prudent to use line thicknesses and spacing in dashed lines that would be reasonably viewed on both screen and for print.

          - Dov

- Dov Isaacs, former Adobe Principal Scientist (April 30, 1990 - May 30, 2021)
    Abambo
    Community Expert
    AbamboCommunity Expert
    Community Expert
    December 5, 2018

    https://forums.adobe.com/people/Dov+Isaacs  wrote

    Solutions? Obviously, part of the solution is for the PDF creator to generate PDF in a manner such that text is rendered as text.

    As I agree to this, the basic issue here is that the programs like Autocad have quite a heavy legacy of several decades and are still producing output for plotters.

    https://forums.adobe.com/people/Dov+Isaacs  wrote

    But the other issue is really a matter for the content creator. If the content creator knows that the content will be both viewed and printed, it would be prudent to use line thicknesses and spacing in dashed lines that would be reasonably viewed on both screen and for print.

    This, however, is very difficult to achieve, because there are a) standards that need to be respected and b) an engineering's drawing is not a piece of art, where you can freely decide what needs to be put onto the paper and what not. You talked about resolution density but forgot to mention that construction drawings are very often designed to be printed out on A0 sized paper sheets or the equivalent in American sizes. So you add to the complexity for the display program, because not only is the printer higher in resolution, but also the drawing space is much bigger on paper.

    So I agree with Dov's analyses, that any program displaying such data on screen needs to do an enormous work in behind the scenes hinting. And the CAD program does not provide any hints on how the lines should be interpreted.

    ABAMBO | Hard- and Software Engineer | Photographer
    Luke Jennings
    Luke Jennings
    Inspiring
    December 5, 2018

    Here is an old thread about the different types of lines in a PDF, you might find something that could help you.

    Line drawings distorted by Adobe Reader's Thin Line Enhancement feature

    Abambo
    Community Expert
    AbamboCommunity Expert
    Community Expert
    November 30, 2018

    YOu need to get the viewers to buy screens with print resolution. This is a hardware problem, not something that Adobe can really address. High resolution screens show the correct lines and width.

    ABAMBO | Hard- and Software Engineer | Photographer
    S
    sscott100Author
    Participant
    November 30, 2018

    But this is a widespread issue, even on my set up and I am using an above-average monitor. You wouldn't think that Adobe expects everyone to go buy a 4K monitor. You'd think that there would be an automatic feature or easily selectable tool that allows you to view the PDF full screen and look the same as it would when printed. Maybe temporarily flatten the drawing or something similar?

    An additional note is that when I plot or print using the Microsoft print to PDF option, the PDF looks a lot better on the computer screen, still not as good as when printed, but better. The issue here is that I think it "flattens" the PDF and takes away any special aspects that the PDF may have. So I am left wondering why can you view the "Microsoft print to PDF" better than the "DWG to PDF"?

    Abambo
    Community Expert
    AbamboCommunity Expert
    Community Expert
    November 30, 2018

    sscott100  wrote

    But this is a widespread issue, even on my set up and I am using an above-average monitor. You wouldn't think that Adobe expects everyone to go buy a 4K monitor.

    No, screens are normally less often exchanged than computers and computers have a replacement cycle of 3-4 years. Screens are at 5-10 years.

    Anyhow, this is not a printing problem. And if DWG to PDF involves the PDF converter of Autodesk then it may even be that Adobe is not involved. Adobe does not control the PDF file format definitions anymore as it is since a few years PDF is an ISO standard.

    ABAMBO | Hard- and Software Engineer | Photographer
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