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Finding scale of a dwg relative to plot size

Hi All, Is there a simple way of finding the scale of a drawing relative to the outputed plot size? i.e. I know my drawings are drawn 1:1, but what is the scale of the plotted drawings when outputed to A3, A2, A1 etc? Is there a built-in function to calc this and add a label it onto the drawing?
Kindest regards, MandyT.


  • Sorry, but there is no straight answer to your question:
    - What exactly do you want to scale? The bounding box around all objects in your drawing? A certain part of it?
    - What exactly do you want to scale to? A DIN/ISO sheet size? With or without printer margins? The drawing area of a titleblock?

    If you want to know the needed layout size of your drawing at a given scale, it might help to insert the attached block into your model, it is 'annotative' and contains the sheet sizes A4-A0.

    For this to work, you have to
    a.) set up your drawing units, and make sure that INSUNITSSCALING is activated (see insunits.png)
    b.) set up your annotation scales (see cannoscale.png) by invoking SCALELISTEDIT.

    If you then insert the block with insertion scale set to 1, it should come in with the correct scaling applied, and give you an idea.
    Note: Although it is possible to set up a sheet with title-block in modelspace and print from there, it is much better to set up a layout page for this.

    754 x 418 - 43K
    754 x 418 - 31K
  • edited March 22

    I did a simple Viewport test on a Layout lately and was
    also very irritated in Bricscad.

    In Vectorworks I would draw in Modelspace 1:1 too
    (beside a visual Scaling, to estimate Leine weights and Font Sizes)
    Paper Space itself has a Paper Size with no Scale or 1:1,
    Viewports get a suitable Scaling, e.g. 1:100, to fit on that Paper.

    VW does automatically scale the Annotation Space to your VP Scale.
    So that you can add Dimensions, Text or Blocks - at the same size
    of 1:1 relative to your Model.

    I recently read that Annotation Scale is no fixed to 1:1
    So does Bricscad work different than what I describe above ?

    At least I had a very hard time to bring my Drawing in Viewports
    to a suitable Scale and Size.
    I think there were so many places in BC to input Scales.

  • Hello Michael,
    yes, everything concerning units and scaling is much too complicated in .dwg.
    This is IMO due to design flaws that Autodesk introduced long ago, and that still cannot be corrected for the sake of compatibility.
    A reasonable scaling system would need just three input values (model units, layout units and a scale), plus a flag on objects that tells the system if their size is to be interpreted relative to the model or to the printed output . In .dwg we have a plethora of scaling features and related variables, yet in spite of its overwhelming complexity, the system is still incomplete: Layout units are not properly declared, and there are objects that lack the 'annotative' flag (linetypes and tables).
    I think that a deeper discussion of this subject would be advisable - as it stands, trying to explain scales in .dwg to our ArchiCAD-trained staff would be an immediate show stopper for BricsCAD.

  • Thanks Knut.

    I see that even the Layout has its own Scale !?
    Can it be that this value should be ignored for 98% of use cases and users ?

    I draw in 1:1 real world units,
    I personally don't make use of any Scaled Blocks myself ....
    (OK, could be, when I don't accept standard Millimeter INSUNITS, that
    Bricscad provides me with Scaled Stuff from Components and such)

    So to get generated plans out on a PDF ....
    (maybe at 1:50 - 1:200, on some A3 - A0+ Sheet)

    .... would it work when I just care about Viewport Scale and ignore all the rest ?

    (given that I do everything in Model Space and completely renounce of the
    Annotation Scale complexity)

  • Hello Michael,

    annotation scale in layout should IMO be ignored not for 98%, but for 100% - it should simply not exist.
    If you work in millimeters in modelspace, you are already on the safest side, and should not experience many problems... setting your viewports to the desired scale should be enough.

  • Yes, beside Annotation Scale ...
    If you set your Layout Space Paper Setup,
    there is even an additional Scaling option for your Paper Space !?
    (Maybe to print a Layout meant for A0 on an A4 Paper or whatever ?)

    Yes, Millimeter.
    Sometimes I do.
    But honestly I think that's the most dumb Unit for Architectural Stuff.
    We think in Meters. Centimeters is quite OK too, if it really needs to be.
    But Millimeter, for me, is the most meaningless and tedious option.

    It is just the still always appearing culprits when fighting against Millimeter
    standard expected INSUNITS and especially the Numblock Komma instead
    of a Point on de_DE Keyboards, that make decimal input useless and annoying,
    (Just a Microstation and Bricscad only behavior, other Apps work well)
    which drives me to try Millimeter from time to time.

    If I just only could set any INSUNITS which Bricscad prefers,
    But work in my preferred current WORKINGUNITS only,
    I would be so happy.
    The worst what can happen is INSUNITS auto adjustment in DYNDIMs.
    DYNDIMS will show dynamic Units, like Meters (according to current distance),
    but when I input Numbers it will want current INSUNITS units or expects
    that I need to manually type units symbols.

    If you throw out all other Units in Settings : File Preferences,
    except your preferred Units, it will work fine.
    But although in File Settings, it is a Programm Setting in reality.
    So if you work in a new File with different INSUNITS,
    your DYNDIMS will always show wrong Units, different from input
    Or better, I need to check each file I opene for its INSUNITS Settings,
    before I can be sure what Numeric Input I will need.

  • @MandyT said:
    ..... Is there a simple way of finding the scale of a drawing relative to the outputed plot size? i.e. I know my drawings are drawn 1:1, but what is the scale of the plotted drawings when outputed to A3, A2, A1 etc? .....

    The simple way is to use a Viewport on a Layout tab. A Layout tab is a virtual sheet of paper, and a Viewport is a virtual hole cut out of the sheet of paper so you can look through it into modelspace. When you first create it, the viewport is like a glass door or window. But if you double-click in the viewport, that will open it, and then you can zoom in or out to make the full-size drawing that you see through the viewport larger or smaller, just like a zoom lens on a camera; i.e. it will change the scale of the drawing. You can also read or set the scale of the viewport in the Scale lines of the Properties panel whenever the viewport is the only entity selected.

  • edited March 23

    Dear guys, it's all explained in full here:
    The main problem in a dwg is that it is unitless. You draw using drawing units (DU), which can be any unit, imperial or metric.
    To tackle this problem when printing, there is Paper Space, which has a Plot Scale setting for each layout. The name of this setting is a bit misleading, because it sets the scaling between model space and paperspace. When working in mm or inches, it's rather easy: 1 printed mm (or inches) = 1 drawing unit. When 1DU is different from mm or inch, than you have to adjust the Plot Scale setting accordingly. E.g. when 1 DU = 1 m, then the Plot Scale should read: 1000 printed mm = 1 Drawing units. Once the Plot Scale setting is properly defined, the plot output scale is set by the Standard Scale property of each viewport

  • edited March 23

    Thanks Louis but I don't get it.

    Autocad unit-less, maybe.
    But I think it is a standard in Bricscad or any other CAD App, that users
    care and define proper units. So that point is fixed.
    Then we have Viewports as Anthony described.
    We define Viewports for a specific drawing - with a specific Scale, like 1:100

    Why do we then need a Paperspace Scale at all !?

    Paperspace is 1:1 Scale of a Paper Size.
    Usually quite smaller than a Building. That is why we scale our Drawings

    That would basically mean that we would use only Viewports of
    the same Scale on each Paper.
    Could likely be that we output a single Sheet of Detail Viewports with
    1:2, 1:5, 1:10 and 1:20 Scales. So I see no advantage in setting a Paperspace
    Scale of a middle-Scale and additionally adapt-scale those VPs that deviate.

    Or are there Autocad users that directly draw in Paperspace instead of
    Model Space ?
    (And if, why don't they draw in adequate Paperspace Units like Centimeter,
    which we did when drawing by hand and ink ?)

    I can't imagine more than these Numbers :

    • Model Space - drawing 1:1 in suitable Units
    • Viewports in suitable Scale so that they fit on a ...
    • Paperspace - 1:1 of a Paper/Plot/PDF Size
    • Annotation Space on top of or part of a Viewport,
      which uses the same Scaling of the Viewport to draw supplements
      like Dimensions in 1:1 to Building size
    • Paper Space/Paper 1:1 Scale to draw supplements like Title Blocks
      in 1:1 to Paper Size

    I mean there may be certain situations where it may be nice to have
    the option to overwrite Scales for Annotation Space or even Paper Space
    and such. But not at the same importance in the User interface.
    Better hidden behind an advanced at your own risk mode.

  • Michael, that's all well and good for people like you and me, but what about masochists? The Autocad system has enough settings to accommodate anyone. With enough customization, you can even make it work the way a sane person would have designed it to work.

  • Hello Michael,

    I think much of the confusion is due to the fact that there are two basic approaches of dealing with scales in .dwg.

    One is the approach that Louis referred to, and that is described in the help page: All drawing - in modelspace and layoutspace alike - is done using one and the same DU (drawing unit). This makes setting the scale of viewports straightforward, but unless your DU is mm or inch, it needs a second scaling operation to convert your layout to printer ('paper') units - the main reason for the scaling option in the page setup - and you will also have to scale linetypes in layout.

    The other approach is to draw in model space in a unit that seems apt for your design (usually mm for MCAD, m for AEC and GIS in Germany), but to always draw your layouts in printer units (mm for metric, inch for imperial setups). This renders setting the scale of viewports more complicated (needed some simple math before annotative scales were introduced), but you don't need to scale your layout to printer units, nor your linetypes in layout then.

    I always adhered to the second line of thought, and I am not about to change that - all my drawings are set up that way, and I am not the only one who did so. For example, ArchiCAD allows you to use m as drawing units in model and layout alike, but if you write out to .dwg, the layout space gets converted to mm. Also, many templates that ship with BricsCAD (e.g. default-m.dwt) are set up this way, although their scale lists are IMO not correctly adjusted (e.g. 1:100 is defined as 1 paper unit = 100 model units, where it would need 1000 paper units = 100 model units in this case).

    Lately though, Bricsys seems to adhere to the first approach - if you enable PROPUNITS length formatting in a drawing that uses m for the model (with INSUNITS properly declared) and mm for the layouts, the millimeters in your layout will display as meters in the property panel, which is bad. On the other hand, Bricsys now introduced INSUNITSSCALING, which when set to 3 will handle copy/paste operations in layout correctly also between drawings with different model units, which is great.

    BTW, I do not agree with Louis that dwg should be seen as unitless, a drawing can IMO only be regarded as unitless if INSUNITS is set to zero, for which use cases are rare.

  • edited March 24

    @Knut Hohenberg
    "BTW, I do not agree with Louis that dwg should be seen as unitless, a drawing can IMO only be regarded as unitless if INSUNITS is set to zero, for which use cases are rare."
    When I say a dwg is unitless, I mean that the unit = Drawing Unit (DU), which can be any unit. The INSUNITS variable sets the unit that the author of the drawing has chosen. As long as you stay within your 'own environment', INSUNITS can be zero because the variable is only used to correctly scale the geometry when copied between drawings that use a different DU.

  • Yes,
    maybe I forgot the issues with Line Styles, Line weights, Text Sizes, Hatch scales
    and such things in my Simplification above.
    Unfortunately overall it is too complicated for me to use or follow.
    Thank god I normally have no need for Plan Output :)

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