Confusion about PSLTSCALE setting

Gary Adams

This setting seems to be working in just the opposite manner described in Help.

When I set PSLTSCALE = OFF, the linetypes in paper space appear exactly as they do in model space.

Setting PSLTSCALE = ON, the linetypes in paper space are drawn with no paper space scaling applied.

Help says "When set to 0 (zero) or OFF, scales linetypes are scaled the same in model space and in layouts, when set to 1 or ON, linetypes in layouts are drawn at the viewports scale."

What am I missing?

Knut Hohenberg

Yes, this is kind of complicated, and the help text seems to be misleading...

If PSLTSCALE is on, LTSCALE will be applied to entities regardless of the viewport scale.

Maybe best explained with an example:

Let's assume the following:
- your paperspace units are millimeters
- your model space units are centimeters
- your intended plot scale is 1/25
- your linetype definition contains paperspace (layout) units, e.g. dash/gap lenght is defined in mm
- you want to see the correct linetype scaling when working in model tab

Then your drawing setup should be like this:
- LTSCALE should be set to 2.5 (1/25 *  10mm/1mm, scale * model units / paper units)
- PSLTSCALE should be OFF (0)

In layout tabs, the linetype scaling will then be correct for viewports that have their scale set to 1/LTSCALE (0.4 in our example).
 
But if you then want to additionally place a detail viewport (let's say in 1/5) on the same layout, the linetype scale in this viewport would be too big.
To have linetypes scaled equally in all viewports, you would have to set LTSCALE=1 and PSLTSCALE=1.

Hope this helps...

Anthony Apostolaros

 Psltscale is a difficult thing to describe. I think of it this way:

"Scaled the same" (psltscale off) means that a 10' long line consisting of 10 dashes in model space will also consist of 10 dashes when viewed through a viewport, regardless of the viewport's scale.

"Drawn at the viewport's scale" (psltscale on) means that the same 10' line will be adjusted to consist of as many dashes as necessary so that the dashes each measure one foot in paperspace.

Alternatively:

When PSLTSCALE is off, the length of a dash is its length in modelspace.

Turning it on means that the length of a dash is adjusted for the viewport.

Knut Hohenberg

You might also say:
With PSLTSCALE=1, LTSCALE is applied to all entities as if they had been drawn in layout space.
What I said above was a little incomplete: I assumed that the linetype scaling of individual objects was left to 1.
Of course (as the help suggests) it is also possible to give all entities in model space a linetype scale of 0.1 and set LTSCALE to 25.

Anthony Apostolaros

"With PSLTSCALE=1, LTSCALE is applied to all entities as if they had been drawn in layout space."

That's good; very concise and clear.

I wish I could edit my earlier post and delete at least the second part, which I see now is not clear at all.

John Gaunt

Psltscale seems to have at least unexpected effects, if the ps layout is set to plot at 1=1 and the plotted scale is say 1=50, with Psltscale On. Then Ltscale has to be changed to see linetypes properly in Pspace, changed back again to see them in Mspace. If you manage to remember where those settings are at, you have to do it in each Layout since Psltscale setting is per layout. And it requires a Regen to reflect the changes.

I think I've got that right. At least it's how I arrived at all Layouts being 1=1 and Psltscales in each layout tab Off, to have the least amount of remembering to do.

Gary Adams

 Thanks all for your explanations.

At least it doesn't appear that I'm the only one having problems understanding PSLTSCALE.

Nenad Bikicki

Maybe I misunderstood something. In our work we don't use PSLTSCALE at all and let its default value. But we change option in Menu settings:

Settings/Drawing/Viewports, layouts and tabs/Paper space linetype scale to No special linetype scaling

Linetypes in both model and paper space are equal then. In that case we accept one value for main drawing scale in model, and then for others proportionally (for example 25 for 1:50, 12.5 for 1:25 and 50 for 1:100). Of course it depends on line type and drawing units (mm, m, inch or like).

We like this approach because we don't draw in paper space except paper formatting, firm logo, frames, tables, some comments and notes.

Once more I apologize if I missed the point and explaining something trivial.

Knut Hohenberg

@Gary
No, saying that you're not the only one having problems with this is a great understatement - I think that all AutoCAD users have problems with scale related settings.
The not so savvy ones simply don't manage to view/print their drawings in a consistent way, the more savvy users are constantly annoyed by the fiddling it takes.
Autodesk, of course, must have known for decades that the way they handled scale was flawed, so they quite recently came up with a solution - the 'Annotative Object' feature.
Since Bricsys doesn't have much choice than to follow Autodesk on its convoluted paths, I just consulted the Acad 2012 online help, to see what we can expect... and it makes me shiver:
First, the system is complicated - one new command and seven new variables:
OBJECTSCALE - Adds or deletes supported scales for annotative objects.
SAVEFIDELITY - Controls whether the drawing is saved with visual fidelity.
ANNOAUTOSCALE - Updates annotative objects to support the annotation scale when the annotation scale is changed.
CANNOSCALE  - Sets the name of the current annotation scale for the current space.
CANNOSCALEVALUE - Returns the value of the current annotation scale.
ANNOALLVISIBLE - Hides or displays annotative objects that do not support the current annotation scale.
SELECTIONANNODISPLAY - Controls whether alternate scale representations are temporarily displayed in a dimmed state when an annotative object is selected.
MSLTSCALE - Scales linetypes displayed on the model tab by the annotation scale.
plus all the existing stuff (Object linetype scale, LTSCALE, PSLTSCALE, DIMSCALE) left untouched - I wonder if this really can make life easier for the average user.

Second, (as far as I could understand) it fails to solve all issues: since annotative scale is limited to certain objects (Text, Dimensions, Hatches, Tolerances, Multileaders, Blocks, Attributes) and MSLTSCALE is a global variable, there still seems to be no way of having some linetypes (eg. an insulation drawn with a 'batting' style) scaled to model units and others (the vast majority) scaled to layout units.
This looks so pathetic that I am tempted to write on to describe how simple a decent solution might have been, but this post is already too long and I better get back to work...

@ Nenad
'No special linetype scaling' means PSLTSCALE =0, linetypes displaying equal in model and paper space should be a coincidence then...

John Gaunt

Incredible amount of effort you have gone to, Knut. The crappy Psltscale system is unworthy of so much effort.

Knut Hohenberg

John, you're probably right, but when I think of all the time that people waste dealing with this crap, I sometimes get carried away.
Like you described in your first post above, I also can't always remember all the things that constantly need to be set, luckily there is LISP which is sort of a remedy for me...

Gary Adams

 Knut - 

Sounds like the MSLTSCALE setting is pretty much the opposite of the PSLTSCALE setting.

In my feeble mind, it seems that you would logically only need to have one of the two settings, not both. 

Knut Hohenberg

Gary,
I did not lay my hands on an AutoCAD version that contains this feature (and I have no intent to do so), therefore I can just tell what I figured out from the online docs:
I think MSLTSCALE automates the task that John mentioned above: if you use PSLTSCALE=1 and LTSCALE=1 in layouts to get uniformly scaled linetypes in all viewports and paperspace, you have to switch back to PSLTSCALE=0 and a proper value for LTSCALE when you want to work in model tab. I bet that with MSLTSCALE=1, you can leave PSLTSCALE and LTSCALE set to 1 and still get correctly scaled linetypes with TILEMODE=1. Just a bet, though...