different dims on same object?

[Anonymous]

can someone tell my why i'm getting two different dims on the same wall. my overall dim is 20', the string dim ads up to 19-11 3/4". i've been very careful to make sure the end points are the same in both sets of dims, and no matter how many times i do it or how careful i am, i get the same result. i've never had this problem before now i have it in two places on the same project. one wall i have two sets, one overall and one string, and on the opposite wall i have one overall and two strings. one string does not ad up while the other does. wtf?
wb

[Laszlo Nagy]

Could be a rounding issue.
Let us say your dimensions are rounded to 1/4".

You have these three dimensions:

7'-4 11/32"
6'-4 11/32"
6'-3 10/32" (which is 6'-3 5/16")
Their sum is 20'-0"

Because of rounding they are displayed as :

7'-4 1/4"
6'-4 1/4"
6'-3 1/4"
The sum of these three values is 19'-11 3/4"

It is because they are all rounded downward for display and those little rounding errors add up to a small difference in the end.

[Anonymous]

His problem may be more serious than a rounding error and within Archicad. My first attempt at creating a building slab was done on one where I had no fractions other than 1/2" and were all entered from the keyboard. The overall dimension displayed as I wanted with a whole foot shown. The individual segments all displayed correctly, except for one that displayed a 1/4" segment.
Any attempt to revise that segment, revised the overall so that it displayed a 1/4" value.
It certainly makes me nervous about trusting the dimensioning in Archicad.
I know that folks will leap to it's defense, but after twenty plus years of CAD use, I understand rounding, use grid snaps faithfully, and sure don't like seeing that in a mature program like Archicad.
I intend to be very careful in my checking for those kinds of errors in the future.
Happily learning Archicad,
Woody

[Anonymous]

I did play with it and found that i couldn't get it to change no matter how many times i tried. i had to manually change the number. when i created the slab, in this case, i created it by typing in dimensions, so how it could be off is beyond me. this is too scary. it means i'll have to check every string. i kind of defeats the purpose doesn't it? is it a bug?
wb

[Anonymous]

What you're describing above sounds like you're dragging objects to their length and depending on what's reported in the tracker to be absolute when it is in fact not. However you say you typed in the dimensions which perplexes me.

One thing I do is to create a hidden layer for notes and such. Then I create lines, by typing in the dimension into the tracker, and use that line to "physically" check that distance. This method also is nice because it can show evidence of if I've been there and how much thinking I've done in that area.

So if I were you, I would draw a line of the length you need and use it to compare to the length you're have having trouble with. You can also draw lines of the distance broken up as well and use them to check each distance individually.

[Barry Kelly]

Don't forget you have working units and dimension units and these can both be set to different levels of accuracy.
I usually work in the highest accuracy I can and dimension to the accuracy required.
Barry.

[Laszlo Nagy]

Barry wrote:
Don't forget you have working units and dimension units and these can both be set to different levels of accuracy.
I usually work in the highest accuracy I can and dimension to the accuracy required.
Barry.

Yes, I am doing the same.
Another thing I always do is I never really trust a machine.
Even when I input my model I am checking it if does what I want it to do. This is e.g. why I still like the coordinate box: it is so easy and fast to just put the User Origin on one end of a Wall, move your cursor to its other end and quickly check the Coordinate Box whether it shows the value you expect.

But I think we metric guys have an easier time. Everything is the multiple of 1 millimeter or 5 millimeters. We don't have stuff like 3 3/8".

[Steve Jepson]

Yes. User origin is the key to finding what is not exactly in the right place.
Dimensions can be deceiving. There is nothing worse to me than a dimension chain that doesn't add up.
Fortunately, you don't ever need to settel for rounding when using ArchiCAD. Your work can be 100% accurate. Don't settle for less.