Angular and Aligned Dimension Inaccuracy

[orwake]

I am working on a floor plan with many walls oriented 45 degrees to normal. On occasion when I check the angular dimension of a wall in relation to others, it deviates from an expecxted polar snap by 0.02 degrees (ie, 44.98, or 135.02, etc) Only some walls seem to want to maintain accurate "snapping" . This in turn causes the aligned dimension tool to not work because I get an error message saying that walls are not parallel to each other. I have tried drawing temporary vertical and horizontal lines to make sure walls are referenced to these. All seems fine (locked dimensions all showing 90.00 and 45.00 degrees) but then when I try dimensioning the distance between 2 parallel walls, it gives the same error and what is most frustrating is that this problem is intermittent. What is going on? What could be causing the walls to snap to such a small increment "off"?
Any help would be greatly appreciated- - I really don't want to have to lock angular dimensions for every corner in this project. .. and then still have problems with dimensioning tools!

[Mr Spot]

All it would take would be to do one line/wall at the wrong angle and then revit would have something to snap to for subsequent walls. You'll need to try to rotate all the walls/lines that are marginally out. Once they are all corrected you shouldn't have a problem (fingers crossed).

[orwake]

Thanks mr. Spot.

You were right, it turned out that I had a washing machine snapped to a laundry room wall at the 0.02 degree error, then another wall referenced off that instead of a wall. One bad apple and all goes tumbling. . . another question tho, is there an easy way to ID objects in Revit similar to the "geometry" values in ADT, giving the coordinates or angular reference to absolute coordinates as an attribute of the object? I see attributes like length, volume, etc. under "dimensions" on the properties tab, but nothing to easily id
angles or give delta lengths, etc.

[Mr Spot]

not Really. You'd have to select the wall to get additional information (in most cases a temp dimension for the angle should appear) or dimension manually or place spot co-ordinates to identify x, y locations of points.

HTH.

[orwake]

I am still having a problem with dimensions in this drawing. I copied out some of the walls to simplify things to a new project and the problem still exists. I still get an error regarding these walls, saying they are not parallel yet they are all 90.00 degrees to reference lines and the room has 4 square corners. How can this be? I have attached a small file.

[Tom Dorner]

Your walls are still off by .002+/- degrees. Change your project units to show 11 decimal places an you will see where the errors are.

What I do to fix these kinds of errors is place reference planes at the correct angle and then align the wall to them so it takes out those minute errors. It also helps in in residential to use grid lines placed at the correct angles to help lock walls and other geometry to. (Define two views, one with grids for working in the other without for plotting or turn off grid bubbles)

HTH

Tom

EDIT: I've attached the file with the problem revealed. I also put our dim styles in the project for you to use if desired.

[LRaiz]

The simplest way to correct the problem is
1) Unlock all angular 45 and 90 degrees dimensions.
2) Select walls starting with a wall that is dimensioned 45 degree off vertical/horizontal.
3) After selecting a wall when you see angular dimension turn into a blue control click on angular dimension value. That will show more digits and and if it is not exactly 45 or 90 then type the accurate angle and hit return. Walls will adjust as necessary.
4) Proceed through the rest of walls.

Here is a useful tip when sketching many walls that are parallel/perpendicular to each other but are not vertical/horizontal.
a) turn on workplane grid
b) rotate workplane grid desired number of degrees
Now as you sketch walls will snap parallel to workplane grid directions instead of vertical and horizontal.
When done do not forget to rotate workplane grid back.

[archjake]

Here is a useful tip when sketching many walls that are parallel/perpendicular to each other but are not vertical/horizontal.
a) turn on workplane grid
b) rotate workplane grid desired number of degrees
Now as you sketch walls will snap parallel to workplane grid directions instead of vertical and horizontal.
When done do not forget to rotate workplane grid back.
I did not know you could do this!
Thanks!

[orwake]

Thanks for the tips! I will definitely pay closer attention to my starting methods and accuracy when starting a project with the majority of walls rotated from horizontal/vertical.

These questions have been raised as a result of this "exercise":

1. Are the problems I was having basically because of my inexperience or because of an inherent problem in how Revit likes to operate? I have a hard time accepting that it will allow drawing a room with 4 seemingly square corners (accurate to the default setting of 2 decimal places) and then tell me that it is not dimensionable due to opposing walls not being parallel. After some experimentation, (I drew a simple room- - - 20 feet square, then forced one angular dimension to be just over 90.degrees) it appears that 0.0018118516 degrees off of normal was considered "parallel" even though the room tapers from 20 feet even to 20 feet and 1/128" at the opposite end) and 0.0018118517 off was over the line into "non-parallel" thus non- dimensionable territory. HMMM?
Where does this program draw the line between what is accurate and what isn't?

2. When creating a reference plane, how can I be sure it is accurate? Surely the 3 decimal places shown by the blue control are not much security. If the popup reading "vertical" or "horizontal" shows up while drawing an element, is it always orthogonal absolutely (i.e. to 12 + decimal places)?

I see that there is a note in the help section on snaps ("More Info on Errors and Warnings") that a problem similar to mine(elements not aligned by .2 degrees or less) can occur while sketching with angular snaps turned off- - - I did have angular snaps turned on while creating my walls so maybe this is not related.

3. Should I have had the "Snap to Remote Objects" turned off? It seems to override the sensitivity of the "Angular Snaps".

4. Using the default template settings, all of the snap boxes are already on. Is it a good idea to change these from the start if working "on the angle"? They have not served me well thus far.

5. As a casual user of ADT for a number of years, I am nearly convinced that Revit is for me, but I am frustrated by it's seeming lack of accuracy or relation to absolutes. I mentioned earlier a desire for geometric id's for elements in the properties dialog such as coordinates or delta x,y z values and angular dimension (in relation to normal) as found in ADT.

6. In Revit 8.1, I see there is added a choice for Aligned Dimensions as well as Linear Dimensions. It seems that my "aligned" works where "linear" should (on orthogonal elements) and I can't get linear to work at all. ? ? ? what am I missing?

[Steve_Stafford]

In general I like to leave all the snaps on and occasionally use the override to turn them all off. More often using a keyboard shortcut to force snap endpoint or snap center etc. Using the grid is a nice technique.

I attached an image to explain the different dimension options, linear versus aligned. The terminology seems to confuse folks pretty consistently.

The image also depicts stretching a wall and getting the parallel indication but notice which wall it is finding as parallel, the far left angled wall. So you do need to pay attention to which surfaces are being used as a reference. As Chris (Mr. Spot) said, it only takes using one bad reference to propogate errors.

It is also a good idea to add dimensions on angle conditions to check that you've got a rational angle. Good idea for radial work too. Not much fun going back to fix wild radius values.

I find a great many such errors can be traced directly back to using dwg files as an underlay to start laying out a plan. As much as folks like to believe they are drawing accurately in AutoCAD/ADT/Microstation I haven't found a dwg file in months that didn't have errors. Very often it can be traced back to two walls that are supposed to be aligned across an opening but aren't by a minute amount. When you sketch walls over these lines and snap to endpoints you introduce this tiny angle. A sure fire way to know you've got a problem when tracing a dwg is if Revit doesn't automatically offer a snap option at the other end of a wall....watch out...there's an error waiting for you! Now if this file started life clean then it goes back to what Chris said.

Just some thoughts.

[sbrown]

The biggest tip I can give is DON'T trace an autocad import for your plan, if you are concerned about inaccuracy, in my experience lines will be slightly off parallel and revit will try to snap / align to those lines throwing you off. Basically I think revit is more accurate and thats why you are having your problem. another tip is to use the shift key when drawing straight walls/ref planes, its like ortho. Also turn on the grid as mentioned before. You'll start to see visually when things are off slightly, if you zoom out and see a little jog in any line you'll know something is off.

[orwake]

Thanks again to Mr. Spot(Chris), Tom, Leonid, Steve and Scott!

These forums are the best Help tools ever!

fyi, my errors were all my own- - - I cannot blame the tracing of an imported autocad drawing, etc. I think my problems initiated from manually stretching wall end points to join with others without paying close attention to perpendicularity. If I use trim/extend tools where I want 90 degree connections, will that assure me of perfectly square corners assuming I start out cleanly?

Re: linear vs. aligned dimensions: Revit 7.0 (I think 8.0 also) had a single button (labeled linear) under the dimension options which worked for aligned dimensions. 8.1 has gone to separate buttons. Thus the confusion regarding this terminology. To be accurate in generally accepted terminology, both aligned and orthogonal dimensions are both subtypes of linear dimensions, aren't they? It seems that Revit has decided to make the terms "linear" and "orthogonally linear" one and the same with the extra limitations of using only endpoints of elements (not anywhere along the element, even if it is aligned orthogonally) or centerlines of elements such as walls as starting and ending points. IS THIS CORRECT?