[BUG (or bad by design)] LO can't export lines thinner than 0,1pt


#1

I discovered today that viewports set to have a thinner line than 0,1pt gets the line width 0,1pt on export to PDF. In the LO viewport they are displayed with a smaller thickness and there is no indication such thin lines aren’t allowed.

This can be problematic when you need to use a pattern but don’t want the drawing to look too heavy.

Here I am using 3 stacked viewports with different line width, but on export the two thinnest both gets the same line width, making the framing very hard to distinguish.


#2

Do you have display line weights in your .pdf viewer enabled?

Charlie


#3

Yup. I even opened in illustrator and read the value there so I know for sure it is changed on export.


#4

There’s a limit to how thin lines can be and still be printed. I’ve run into that when I’ve tried to use very thin lines and had them not show in the print.


#5

Good point. I’ve increased all line weights instead and hope the difference is enough to make the important lines prominent over the less important ones. Anyhow it would be nice if LO either displayed a warning or simply did nothing if the lines were to thin. Silently changing thickness is not transparent and makes it difficult to understand what is going on.


#6

I wonder if it’s the exporter that does it. Who wrote the PDF exporter?

If you are creating PDFs for printing, it might be worth making up a sample page with lines of various weights and styles to see how the look printed. My guess is some dashed line styles may not appear on paper even if they are a bit heavier than solid lines.


#7

I had an issue a couple of years ago where very thin lines didn’t plot. I increased every line thickness since then to thinest=0.15


#8

One of my clients prints projects I do for them on Arch E paper. The printing process they use means that lines that are less than about 0.3 disappear. When looking at the overall sheet, those lines are nearly useless anyway so the thinnest I go is 0.6.


#9

I would agree it would be nice for user’s to be able to set min linewidth in some kind of print profile (style).

At least in SU2016 it’s …


#10

0.1pt is quite thin compared to that the best raster export that LayOut can do is 300 dpi. A 0.1pt dot requires 720 dpi output.

The limit might be embedded in the PDF format itself. PDFs from CAD drawings that I have looked into are noticeably more inaccurate than the original. Maybe examining a PDF exported from an Illustrator drawing with “hairlines” could provide useful information.

There is also a limit to the capability of PDF exporters. At work we use Adobe Acrobat, and to provide for the large paper sizes we sometimes use, we have had to limit the output resolution to 600 DPI (from the default 1200), otherwise it fails to “print”.

Then there are ISO standards for technical drawings that require the thinnest lines in a drawing to be about 0.5 pt, and that the other lineweights are always double the weight of the next thinner one.


#11

I use 0.15 because it is more accurate to work with in Layout on screen. I also use double viewports/scenes for lineweights so it just works nicelly with the style settings I have in sketchup. The printer also prints as thin as it can, even if it cannot print as thin as specified.


#12

I’m with @DaveR the line weight for the PDF isn’t as important as the line weight on the printed paper.

.1pt = 0.035mm that is a very very thin line.

I’m old school so I still think of drawings in terms of physical pen widths where the smallest pen width I had was 0.13mm which is about 0.35 pt. These days 0.1mm, which is about 0.3pt, is my thinnest line. With my timber framing outline being around 1.4pt depending on scale.

Another way of differentiating line weights is by using shades of grey. A 50% grey coloured line will recede. This is particularly great for hatches and background lines, and in my opinion makes the drawings look great!

Love your insulation hatch @eneroth3 , is this a material / skalp thing or have you drawn this in sketchup?


#13

It would be absolutely wonderful if there were a set of instructions on the most efficient method(s) for printing files of LO documents that have been exported to pdf. I have searched and so far this thread is the most informative I have seen on the subject. Even with a fair amount of SU/LO experience, I continue to have problems obtaining desired line weights and line types more often than I care to.


#14

If I remember correctly the line weights in sketchup/layout are a combination of the sketchup style settings and the layout style line weight setting, where the former is multiplied by the latter.

So for example,
Your sketchup scene has a default style with the following edge settings: normal edges = 1 (the default minimum), profile lines = 2, and section cut widths = 3.
Place the scene on a sheet in layout and apply a line weight to the viewport style. Lets say 0.5pt.
Layout will then multiply the sketchup style line settings by the layout line weight setting to arrive at a final displayed line weight for each element.

So in this example layout will output the following lineweights:
normal edges = 0.5pt, profile edges = 1pt and section edges = 1.5pt.

If you are tricky you can use this functionality to stack viewports for a wide variety of lightweights in your drawing however there is a trade off in time and performance so you need to find a level that works for you.

Line types (dashed etc) are more of a problem. For lines that are unlikely to change such as boundary lines etc, I tend to draw them in sketchup, output a “dashed lines” scene to layout, place the viewport and explode it. Not the best way in terms of sketchup links but it is quick.

Hope this helps.


#15

The Line weight setting in the SketchUp Model Styles tab is indeed a multiplier for the weights of the lines from SketchUp.


#16

Me too. And there was that transition period when I had a pen plotter and had to coordinate the the line point size to what the plotter would produce and also have the same results on a laser printer. I dug up a work sheet I did 25~30 years ago for this. (Amazing it still opened)

Pens, points and pixels-0,3.pdf (29.8 KB)

Starting with a series of pens that are Sqrt(2) times the last in mm, and seeing that 1 mm is approximately 2.8 points, I settled on a series of line weight in points that go .35 pt, .5 pt, .7 pt, 1 pt, 1.4 pt and 2 pt. I also have .25, .12 and zero on my list, but seldom use them.


#17

I know that these lines are very thin. This is however a diagram for a report in A4 format so lines need to be quite a bit thinner than on a construction document or wall hang poster. I’ve already increased the lines and I think I’ll reorganize my document to have only 2 line widths as I don’t want the thickest lines to be too heavy.

However it still bugs me that LO silently changes your data. I have made several test prints and if the printer failed making the lines I wouldn’t mind because then it would be very easy to understand it is the printer that doesn’t support them. The problem is how this is silently changed on export and that it is hard to figure out what is going on.

I suspect this is something that comes from third party PDF exporter. When accidentally setting viewport widths to 0.01pt and print directly from LO, not via PDF, the lines are printed incredibly thin but they are printed.

The difference in PDF export and printing inside LO suggests this is unintended.

Thanks! They are drawn inside of SU using arcs, lines, scale and Eneroth Cylindrical Coordinates for the bend.


#18

I sometimes use a grey color for less important lines. I don’t know if this will help your problem, but could be
worth a try. this will only work though if you use ‘By material’ in Styles.


#19

In the case of Post Script, IIRC, you can call for a line weight of zero, but when you do so the output device prints the finest line it is capable of, so it should always print something. I would expect any program to hand off line weights to the printer without messing with them.

Way back, I did a bunch of experiments on what the actual line weights came out as when printed. Drafting pens were pretty close to what they claimed, but my first Laserwriter, which was 300 dpi produced a line of about 1/150 inch at the finest end and then gradually got closer to what you asked for as the weights got heavier.


#20

In graphics applications this is usually called “hairline”. Maybe LayOut should also have that choice. I also understand that PostScript has an internal limitation on precision. The experiments I have long ago made of exporting and importing PDF files fro CAD apps always lost some precision.