Friday, 27 June 2014

Revit linked files and worksets

Recently I had a model that kept turning of a linked file. I was bit curious what caused this behaviour as I was under the impression that I didn't do it. Today I wanted to test something shortly with worksharing visibility in a linked file and I suddenly found out what was the cause of my earlier problem.

I made this very simple model with three worksets. I made these worksets names on purpose. (First of all I would like to point out that I never create worksets as if they are Autocad layers but for this simple test it is okay.

So what was the setup and what did I forget to do...
I have a file with a link. I selected the link in canvas and changed the workset to the one I called link_Wv
Then I turned of this workset Wall (bad name) and suddenly my link was gone... I select the link in the project browser and suddenly it became all to clear to me. I had changed the workset assignment of this instance of the link ( in the instance property window). I should have changed the workset assignment in the type properties of the link. 

So the proper setup for linked files in workset should be:
A workset for controlling the entire link and in case of multiple instances of that link you might want to create a workset for every instance of the link.

So if your linked file behaves erratic when turning of worksets, select the link in canvas and check the instance properties of the link and the type properties of the link.

An example with pics:
the link on a workset:
every instance on it's own workset

Be aware the goal of this setup is to keep the load smaller for your computer and not to controle visibility.

Monday, 23 June 2014

Revit make up your mind

I was busy again with shared coordinates the other day. To check something I had Revit's decimals set to it's maximum. I had to measure a linked Autocad grid and I wanted to know where things are going wrong.

I have this Autocad grid setup. Everything nicely spaced at 7200mm
I also copied this grid and rotated it. You see that also Autocad is subjected to mathematical rules so the dimension are of.  
Next I linked this grid into Revit
Autocad and Revit seem to agree. (The red dimension lines are from Revit and the black ones from Autocad)

What about the rotated one
Autocad seems to agree with it self but Revit can't seem to make up it's mind.

So far I was measuring Autocad lines in Revit. What about grid lines created directly in Revit...

I even tried whether it matters if you first create an orthogonal grid, copy it and rotate it. (it doesn't matter)
Now this all may not matter much because it's so incredibly small but it's really odd that when you measure something in revit and you move your cursor around before placing the dimension line it matters where you click for the measurement.

This all started with someone mentioning to me that picking gridlines from an Autocad drawing is not a good idea. It's better to create them native in Revit. I think I'll agree.

Friday, 20 June 2014

The space between the bit 0 and 1

Coordinates again and again and again and probably more to come

Revit, as you might know, increased it's area of where you may model your project. It used to be a circle with a radius of 2 miles = ( 3.218688 kilometer) and they scaled it up to 20 miles = 32.18688 in Revit 2011.

I opened a file recently we had received and I took a look at their survey base point and project basepoint. First thing I noticed was that the survey point was unclipped... That's odd I never unclip it, because it needs to stay at 0.0.0 (at least for people who work with a coordinate system like the Dutch rd system. The next thing I thought was odd are the values of the survey point.
Normally I don't use so many decimals but something in this file triggered me to set the units this way.
I don't think anyone would on purpose enter those survey coordinates. So what happened here? As there are some mathematical rules every cad program has to abide to I was getting suspicious. Could it be that we are dealing with rounding? 

To test this theory I created this spectacular drawing in Autocad: a square, lower left corner at coordinate 100km, 400km and each side is 100 meter. 

I linked this drawing into a Revit project. Next I moved and rotate it in the right position. The culprit here is the rotation... I rotated the drawing 60.389 degrees clockwise. So when the drawing was in the right position I acquired it's coordinates. 
Notice the N/S value! I don't think that Revit is here to blame this is mostly a mathematical issue.

My first advise don't rotate dwg files to align it to be able to draw orthogonally so don't use project north and true north. Use a rotated scope box as I have explained in this blogpost:

My second advise be careful with acquiring coordinates from a dwg.

My third advise is to manually create a point in an Autocad file. 
Make sure that you move this point to an integer xyz value (rounded) what is an integer
Use these values an insert them into your project base point. Leave the rotation to the scope box.

If you do start to use the rotation trick, stick to one methode. I ran into a file where they had rounded the rotation but started to pick lines from autocad that had apparently the same rotation. The revit rotation was 60.389 and the autocad rotation was something like 60.3887274766673 You might think that is trying to be overly precise. But this has the following effect: The same point 100 meter away from the project basepoint is almost 1/2 a millimetre apart between these rotations. At a thousand meter is't 4.5 millimetre apart. That's still no problem if everyone uses the same rotation. But what if someone uses the autocad file and the other one uses the rounded rotation in Revit. This can seriously screw up you Navisworks clashdetection!

Wednesday, 4 June 2014

Revit minimal wall height

Apparently the minimal wall height seems to be 1/10 of a foot. Why I don't know. It seems odd to choose 1/10 of a foot. Since Revit's engine is by design build on the backwards archaic  imperial units systems you would almost think the minimal would be an inch...

1 inch = 25.4mm
1 foot = 304.8 mm
1/10 foot = 30.48 mm

If you need a wall to be smaller than 1/10 of a foot you can do so by editing it's profile.

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