topic Re: How to annotate a 3D line length in AutoCAD Forum

How to annotate a 3D line length

Anonymous — Thu, 12 Oct 2017 22:03:29 GMT

Hi Guys,

I am using AutoCAD 2017 and I have a quick question.

Considering I have a 3D line from (0, 0, 0) to (1, 1, 1). Without changing the UCS how can I annotate the actual length of that line?

It should be around 1.73 but I can only annotate it in 1D/2D which is 1 and 1.41.

Thanks.

Re: How to annotate a 3D line length

Alfred.NESWADBA — Thu, 12 Oct 2017 22:11:22 GMT

Hi,

you can create a dimension, then double click the text to edit it, remove the text, then right-click ==> insert field ==> the field can then be defined to show the length of the object.

- alfred -

Re: How to annotate a 3D line length

Kent1Cooper — Thu, 12 Oct 2017 22:11:26 GMT

@Anonymous wrote:

....

Considering I have a 3D line from (0, 0, 0) to (1, 1, 1). Without changing the UCS how can I annotate the actual length of that line?

It should be around 1.73 but I can only annotate it in 1D/2D which is 1 and 1.41.

....

It doesn't do it with a Dimension, but if "annotate" is meant more broadly, the LL command in LabelLengths.lsp, available here, will put Text in showing the true 3D length. See more description at that Post.

Re: How to annotate a 3D line length

Anonymous — Thu, 12 Oct 2017 22:24:19 GMT

Hi Alfred,

Thanks for your help and I know that is going to work. But considering I have 100 edges, it is going to be painful for me. So is there another better way to do that?

Re: How to annotate a 3D line length

Anonymous — Thu, 12 Oct 2017 22:31:36 GMT

Hi Kent,

I tried the LSP file and it works well for me. We can expand the annotation concept more broadly for sure, but does AutoCAD itself support a similar function to show the length of the line? (I know the MeasureGEOM is going to help but it is one-time and then disappear). Since our customer is going to do the measurements, so hopefully we can use what AutoCAD already had.

Re: How to annotate a 3D line length

Kent1Cooper — Fri, 13 Oct 2017 13:19:16 GMT

@Anonymous wrote:

... does AutoCAD itself support a similar function to show the length of the line? ....

@Alfred.NESWADBA's suggestion in Post 2 should work [I haven't experimented] -- I did wonder what happens if you edit the Line by Stretching or something, thinking that since the Dimensioned distance is projected onto the current plane, maybe its definition points would also be "forced" onto the same plane, i.e. not both lie on the ends of the Line. But they do -- the NODes have the different Z coordinates [(assoc 13 & 14) entries in entity data].

Otherwise [for example, in old-enough versions to not have Fields], probably the only way is by changing the UCS, so that the Line lies in the current UCS's XY plane, and then Dimensioning it. But the result would then have the Dimension's text and arrows foreshortened from the WCS point of view.

Re: How to annotate a 3D line length

Alfred.NESWADBA — Fri, 13 Oct 2017 13:23:49 GMT

Hi,

>> I did wonder what happens if you edit the Line by Stretching or something, thinking

>> that since the Dimensioned distance is projected onto the current plane

The dimension text is overwritten, so whatever you do to the line the correct 3D-length of the line will be displayed.

There is no projection calculated, I used the dimension object just to have arrows and dimension line/ext.-lines ... it could be a plain text object too, does not depend, the field is set to show the length of the line and that is what it does (it is fully independent of any dimension points or dimension projection)

- alfred -

Re: How to annotate a 3D line length

Kent1Cooper — Fri, 13 Oct 2017 14:18:55 GMT

@Alfred.NESWADBA wrote:

....The dimension text is overwritten, so whatever you do to the line the correct 3D-length of the line will be displayed.

There is no projection calculated, I used the dimension object just to have arrows and dimension line/ext.-lines ... ....

This is what I was worried about, that turns out not to be a problem after all. Initial condition, with the cyan Line relatively from 0,0,0 to 1,1,1:

Then:

... and if you STRETCHed the Line from some viewpoint like the above, or a side view, grabbing the upper end of the Line in a crossing window but not catching the definition point if it were down in the WCS plane, and you took that upper end another 1,1,1 up and over [doubling its length in the same direction], you would get something like this as seen in plan:

in which the change in the Line's length is reflected in the updated value of the Field as Dimension text, but the Dimension doesn't extend at the right to the new end of the Line, because STRETCH didn't take its upper-right definition point there.

But it turns out that, with the Dimension's right definition point actually up at the Z=1 end of the Line, and not down in the XY plane in which the Dimension is drawn, things work as expected -- the right extension line does move up and over.

Re: How to annotate a 3D line length

Anonymous — Fri, 13 Oct 2017 14:52:41 GMT

Hi Kent,

Thanks for all you guys discussion there, it seems that the Field Area is really a dynamic object and will change based on the real number.

But it did not solve my question, as you all understood, I want a built-in function in AutoCAD which can help me easily annotate a lot of 3D lines as the real length.

Re: How to annotate a 3D line length

Kent1Cooper — Fri, 13 Oct 2017 14:59:20 GMT

@Anonymous wrote:

....

But it did not solve my question, as you all understood, I want a built-in function in AutoCAD which can help me easily annotate a lot of 3D lines as the real length.

Unless and until that happens, I think the second paragraph approach in Post 6, if acceptable to you, could be defined into a command name easily enough in AutoLisp. I don't think that's true of the Field-based approach, but I could be wrong.