The Screen-Based Linetypes feature makes it easier for me to recognize lines’ patterns, but it makes them much thinner. I can adjust for that by increasing their weight, but that makes them too thick when I print. Is there a way to assign different line weights for display and printing? It’s possible that this is because I’m using a high-DPI display. I’m also new to QCAD and CAD in general, so I know it could be something very simple that I’m missing.
Hi,
Screen-Based Linetypes (NL) are meant to look OK on a display what has a much lower dpi than any printer does.
If we clear this option then QCAD will try to represent the lines in there actual weight given the drawing unit.
For printing QCAD uses the normal Linetypes and weights.
A Lineweight of 0.25 will print 0.25mm thick on paper with a global linetype scale set to 1.
It is thus possible to change the outcome on paper by the drawing global linetype scale setting.
There is no setting that I know of to change the appearance on a display.
I think that it uses a 1 px thick line for the lower Lineweights.
And that it scales the Linetype pattern accordingly.
There is a setting to use full resolution for high resolution displays or not.
So you don’t really change the look on your display but you define how it should look on paper.
Linetype patterns can also be scaled by weight or not.
I have the same issue. I am doing architectural drawings in the meter range and even with screen based line types turned on the line thickness are wayyy thinner than later with my 1:50 or 1:100 scaled printing. It would be very handy if there is a setting how much the scalling of the Screen-based Linetypes is applied to. So that i may tune this setting that the lines look roughly the same as with my desired scaling factor (for example 1:50 or 1:100) on my DIN A4 or DIN A3 paper later on the printer. @andrew maybe it is worth a feature request?
Hi,
This is addressed somewhere on the forum.
Model-Space has no paper scale, meaning that there is no reference to scale the representation of the line-art weight and type accordingly. Things in Model-Space can be used in any scale and on any size of paper in a printing stage. The best approach is to use Viewports and Layouts.
NL on is a pixel based representation to look OK on screen in any zoom state.
Dashed and/or dotted always look a bit dashed and/or dotted.
Thick lines look somewhat thicker than thin lines.
Rendering complex Linetypes is avoided. NL off is in true size. Weight 0.25 is then exactly 0.25 mm wide.
It is then possible to zoom in on a dash so that it fills the entire screen, to zoom in on a pattern space without seeing a line at all or to zoom so far out that a pattern space is less than 1 pixel making the pattern seemingly continuous. NL on/off is rendered on screen with at least 1 pixel.
Weight 0.25 or 1.00 is always exactly 0.25 or 1.00 mm thick on paper.
It are the physical sizes of the historical pens with ink and these don’t scale at all.
The difference sits in the Linetype or pattern scaling …
… And not in how thick the line-art is drawn on paper.
DIN A3 is approximately 1.4 times larger than DIN A4.
In full page preview (NL off, true size) it is then logical that a 1mm thick line is represented thinner on the A3 preview compared with the same on A4.
Only on screen, printed it will be exactly 1mm thick on both page sizes.
But it would be very convinient if, for example, i may specify a desired scaling for printing and based on that scaling my Screen-Based Linetypes are scaled accordingly. So with this i do not have to constantly switch between layout pages/blocks and my drawing to check the apperance of my drawn lines.
It is a feature what i am currently missing in my workflow.
Ok i think i have sort of found what i am looking for.
If you activate the Print Preview in your Model Space, you are able to apply a scaling factor. With this “workaround” you see the linewith how they will look later on the paper/pdf.
Are there any drawbacks if i work with activated print preview and applied scaling, that i am not seeing right now??
As said, Screen-Based Linetypes (NL on) is a pixel based hybrid method to work well on screen in any zoom state. Especially useful in Model-View.
It would be counter-productive to use the real pen size.
Draw a 2mm thick line 10 units long on a drawing in meters, auto zoom (ZA) and turn NL off.
It would be just 1 pixel thick until you zoom in to the cm level.
Zooming in further it would indeed be 0.002m thick.
With NL on it is kinda thick in any zoom state, at least thicker than a 0.25 thick line.
And that is the essence of Screen-Based Linetypes.
→ It will never be printed or exported that way !
By default NL is turned off when in page preview mode (Layouts, Print Preview, …)
And by Application Preference turned on in Model-View.
There should not be a reason to constantly switch between page preview and Model.
For CAD usage, Layers are intended to group things that should look alike, printed alike.
Grouping: Continuous, dashed and/or dotted, black, red or blue, thick or thin.
Once you have established a correct representation that is true for all that live on those layers.
Unless you start assigning custom attributes including Linetype Scale to each entity.
For the Linetype Scale that is best done (in advance) by the global scale.
See Drawing Preferences.
Linetype or pattern scaling is another debate because the DXF standard states that they are defined in the drawing unit (meters for example) but they are applied in mm for metric users and in inches for imperial users with the exception of ISO types.
A dash of the ‘Dashed’ type is 1/2 inch or 12.7 mm long for example.
Resulting in about 52 dashes per meter at overall type scale 1:1.
Because this started out on line thickness.
For the record: Scaling does not affect the thickness of line-art.
CAD uses a fixed set of pen sizes and a certain pen comes in one size only.
The pen size of details on CAD drawings is normalized.
It is the representation on screen that may vary.
As in the above, I can assure you that the line thickness on paper is exactly the pen size.
On any page size and in any scale.
Unless you activate ‘Print all lines as hairlines’ of course.
I would avoid to extensively work or draw in page preview mode.
Already a complex state in itself, given the programmatic implementation.
Swapping to page preview is indeed shown in true size because NL is turned off.
Just the same as swapping to a Layout with an already defined paper scale.
If you look closer you will notice that the paper scale affects the representation of the page area and that of the line-art thickness and pattern. The line-art itself remains the same.
How things are represented on paper is a near final stage.
Best governed on Layer level and/or with Layer-states.
For my work it is importand that the drawing is nicely readable in my desired scaling.
Because of that it would make sense to me to have an option, which is obvisouly already implemented through the print preview, to see my linethicknesses in correct relation to my drawing in the desired scaling i want to print it later.
The functionality of the screen based line types as it is right now makes no sense to me. The lines look a little more readable than before but they are not as they look later at printing. So what are the benefit for me here?
A drawing may include several Layouts in different paper scales and defined on different page sizes. Layouts can include Viewports in different scales. Hence, there is no unique paper scale when designing in Model-Space. None or simply 1:1.
You should not be bothered by how thick a line would be when drafting things in real world size.
It is a given fact from the pen size associated with the layer you draw on.
The outcome is very predictable because pen sizes don’t scale.
A line drawn on a dedicated ‘border’ layer defined with a weight of 0.70mm will always be 0.70mm thick on paper and on a PDF export.
The same goes for lines drawn on other layers like: ‘center’, ‘hidden’, ‘outline’, and so on … Each with predefined pen sizes, patterns, colors and so on.
Depending on your field of interest, your engineering branch or even your firm there is certainly a convention on what pen sizes to use and in case, even on which colors that are commonly associated with those.
In other cases you are free to choose them, advisable per Layer as it serves no use to ‘invent’ them for each detail, line or for each new drawing for that matter.
Screen-Based Linetypes (and weights) avoids unworkable thick lines or disappearing dashed/dotted lines on zooming in on details or almost no difference between thick and thin when zooming far out. Mostly because a screen has but a limited dpi compared with modern printers. Details can disappear in between the pixels or take up a large portion of your screen.
Anyway, so i worked the last days in the print preview mode with my wanted scaling and it works realy well for me.
I think in very big real world dimension as it is in architectural design this view mode has more advantages than the Screen Based Line types. The only think which is a little anoying in the print preview mode is that you always see the Page outline and i think the performance is a little lower.
So if @andrew is searching for new feature idears, i recommend to implement a scaled viewing mode how it is realised in the print preview, just without the page outline and good performance of the viewport.
