Dimension questions

2 questions:

  1. Is there a way to tell Rhino to position the dimension in image #1 on the vertical plane rather than the horizontal plane without resetting the C Plane? A key command like ctrl or something that says ‘go up’ rather than ‘over’? I know that this can be done if the object is aligned with the axis by hopping over to the relevant viewport but I can’t get it to move vertically if the object is not aligned with the axis.

  2. Because annotative scaling doesn’t work in perspective viewports I set up a separate dimension layer that I scaled in model space so it would be correctly sized (more or less) when I viewed the object through a perspective viewport. I figured that would be kind of an end run around the problem of annotative scaling in perspective. But the viewport doesn’t respect the size of annotations set in model space. Is there any way to make that happen?

Thanks for any advice you can give.

Hi Arail- dims are always aligned to the CPlane, currently. I do not know of any way around that. As for the scaling, the size of the dimension as set in the dimesnion stlye properties should ber what you see in a layout and any scaling applied (“Model space scale”, if enabled) should be applied when you look at the same dimension style for dims placed in model space. It sounds like you are saying it is not working, correct?


@lowell, is the ability to align dimensions outside of the CPlane on your radar?

Thanks for the quick reply.

First, my apologies for not being clear about terms. In AutoCAD we use the terms model space and paper space to distinguish the two levels. For simplicity I will use those terms here, let me know if there are other terms more commonly used in Rhino world.

As far as the first issue - I will have to learn to use C Planes with more agility than I have now - probably a good thing for someone new to Rhino anyways.

For the second issue - in my first post, I assumed that looking through a perspective detail in paper space, I would be ‘seeing’ the model and therefore I would see the dimensions at the same scale as I set them for model space. Clearly this is not true - I’m not sure why.

I set Inch / Fractional dimension to be 1/8" in paper space and 8" in model space. After reading your post I created a new dimension style called Inch / Fractional for Perspective and set the dimension for paper space at 2" and for model space at 8", assuming that would give me a larger dimension in paper space and the same size in model space. It works for paper space (the image to the right) but for some reason the dimension is enormous in model space now (the image to the left). The dimension 14-5/16" is my usual Inch / Fractional and the 41-1/2" is the custom Inch / Fractional for Perspective

I appreciate all the help you’re giving me.

Hi Arial- [quote=“arail, post:4, topic:1092”]
at 2" and for model space at 8"

the model space scaling in the dimension style (DocumentProperities> Annotation > Dimensions > Dimension style name) a scale factor and not an absolute size. So… just checking… did you set this at 2 to get from 2" to 4", or to 4?


I think I understand what you did.
Just talking about text height in dimensions now - the other dimension size bits work the same way.

The “Text height” setting is the size of the text, whether in model space or paper space.
“Model space scale” is a multiplier for that to apply in model space only.
Setting Text height to 1/8" and Model space scale to 8 would cause dim text to be
1/8" high in paper space units (layout units in Rhino) and
1" high in model space when viewed in a viewport that is not in a detail view.
When you look at a Detail view, but in model space mode, the paper space scale is active. That way dimensoins don’t change size when you click in and out of model space mode in details.

Pascal -
I set dimension size in model space to whatever looks good to my eye when I’m working. I’m not trying to achieve an exact size. That’s only important for dimension size in paper space for me.

I think this image will clarify what confuses me - the 41-1/2" dimension above is Inch Fractional for Perspective, the 14-5/16" is Inch Fractional. They’re both set to be 8 in model space - why are they different? I can use this dimension to control dimension size in a perspective view in paper space but only at the expense of losing control of the dimension in model space.

Again, thanks for your attention to these matters

Making dimensions out of the cplane has come up before and I haven’t come up with another way to select a plane for them.

Dimensions have to be on a plane, so if you picked 2 points with different x coords and different y coords in top view and somehow said Go Up, the dimension would be on a plane not parallel to any of the 3 basic world planes and the distance measured would be in that skewed plane, but if it was just a little off the world x-z (constant y) plane and you looked in front view, it would be hard to see that the distance was just a little off.

There have been some ideas about using parts of objects in the model or selecting from multiple user defined planes, etc. That’s not just for dimensions, but other modeling too. Cplanes are pretty cumbersome to move around and a better interface for them or an alternate way to define a plane to draw on would be nice.

Read and re-read Lowells post and now I’ve got it.

For my Inch Fractional for Perspective dimension to read correctly in model space it has to be set to 1 because the model space setting is not a fixed dimension - it’s a multiplier. I assumed it was a dimension - as in 8".

Feeling somewhat embarrassed but not too much … thanks again.

Hi Arial- those are different because the 8 is a scale factor applied to the ‘Text height’ number, which is 2 in one case and .25 in the other. So the result of scaling will be 8 X 2.0 = 16" in one and 8 X .25 = 2" in the other. Does that make sense?


Pascal - yes, with Lowell’s and your help I think I’ve got a good handle on it now.

Perhaps a dim type that behaved similarly to rotate3d? You pick your two dimension points, then you are prompted for an additional step of choosing the rotation angle which uses the two picked points as the rotation axis, then pick the dimension location.

It would really only work as an aligned dimension, but that might be enough for most cases. Actually, I guess you could use the picked rotation angle of a DimRotated and that seems like it would work as well.

1 Like

make a dimension command that works like the 3pt rectangle tool? (in which you can use parts of the object plus the tab key to constrain the plane?)

I like this idea a lot. I was only asking for a simple command to make the dimension move perpendicular to it’s default plane but with your suggestion of a rotation a viewport could ‘look’ at the model / object from an angle and see the dimension as correctly place.

@lowell I have heard of this request before. Emulating the 3pt Rectangle seems like a good idea. That would satisfy the other customers I have talk to about this.


I like you explanation with the video.

We have taken a few runs at 3d dimensioning. In simple cases it makes sense, but it does not take long to see complications. There are a few nagging questions that always come up. Perhaps we can get your feedback on this.

Take the attached image as an example:

If I use the 3pt Rectangle command as an example and select point 1 and 2, I will actually get dimension C. I am not sure how to get dimension A. I could use smarttrack or control to go vertical. But how do I tell the dimension line to go horizontal on Dimension A after picking points 1 and 2.

A second problem is the difference between B and D. With a normal linear dimension, if you pick points 2 and 3, you will get B. In an elevation of plan view if you pick point 2 and 4 you will also get a dimension that equals B. If we use the Rectangle 3pt interface, there is both a placement a length difference between B and D. D is just off vertical and is slightly longer then B. We see this could be quite dangerous if point 4 starts getting closer and closer to point 3. You could have two dimensions which are different, very close in position and length. It seems you could easily fool yourself on which dimension you have selected.

We could load up a dimension command with a bunch of options in the interface, but does this defeat the purpose of a simple 3d dimensioning command?

I wonder if a dimension could have a plane as part of its definition, and even with current behavior, have a grip available that could swivel it around after the fact, by default pivoting on the two points that determine the dimension.


I think basically what you would want is to use the 3 point rectangle options for picking pt1, pt2 and direction. Then you would basically toggle between a horizontal dimension, vertical dimension or aligned dimension. and then pick the point for dimension placement. That this similar to how others have solved the problem.


another quick video:

[EDIT] actually, some of the methods i showed in that video are overkill… i could of just used the perp snap to set the lines horizontal :oops: … regardless, i think my my wish is to just click between any two points and have rhino give a dimension which will read parallel to that line (hence the rectangle idea) [/EDIT]

so that said, i should probably point out that i don’t use rhino in my work in the same way many others probably do…
i design then build the stuff i design and a computer is with me throughout the project… preplanning/design phases then onsite as well being used as the construction documents… point being, i don’t ever really have to dimension a drawing in the same way a straight architect would need to for presentation/communication…

my current method of bringing numbers to the crew from my model is using the line tool, clicking the first point then setting the second point at the desired location (i don’t click the 2nd pt)… i’ll note the length at the bottom right of the window then write it on a piece of paper or scrap lumber to hand out to the crew… then press esc to exit the line tool…

it works just fine but maybe a little less than optimal because i have to get a dimension then write it then repeat whereas if i could use a 3D dimension tool somewhat like i’m outlining here, i could get all my dimensions at once then write them as a separate step… and i’ll be able to remember if i already pulled a number because the dimensions graphic will remind for me… (and even more optimal than that would be sending the dimensioned drawing to an ipad then hand the ipad to the cutman so i don’t have to write things down. but that’s another topic :wink: )

i do realize there are going to be a lot of situations that i haven’t considered which will throw a wrench in the idea of a ‘fast w/little to no options’ 3D dimension tool and some speed compromises may have to be made in order accommodate more situations but regardless, it’s reassuring to see you all are actively thinking about this stuff because it would definitely be a welcomed capability