Tuesday, 17 January 2012

Navisworks and Revit Quantities

I was fiddling around with parts the other day when I noticed the following.

There seem to be a difference in quantities between what Revit says and what Navisworks says. Here you'll see a screencapture of a revit wall that has been split up in revit parts and the same wall in Navisworks. Looking at the properties in both program of the same wall I can't help but wonder.

Revit says:

Volume       1.408 m³
Area  14.080 m²
Length  3520.0
Thickness  100.0
Height  4000.0

Navisworks Says:
Volume     0,040 m³
Area         1,308 m²

Length 3,520 m

Height        4,000 m
Thickness 0,100 m

I think the properties should be:

Volume     4000mm*3520mm*100mm = 1.408m³
Area         4000mm*3520mm = 14,08m²
Length      3520 mm

Height      4000 mm
Thickness 100 mm

Of course the area to be calculated is debatable because I only calculate one surface of the wall. There are ofcourse 6 surfaces.

Knowing that Revit actually works in the inferior system (oops typo I meant imperial) Let's see what happens if I tell Navisworks that the file I appended should be regarded in meters.

Take a look at the properties in Navisworks now.
Now Navisworks says:
Volume 1,408 m³
Area 14,080 m²
Length 11,549 m
Height 13,123 m
Thickness 0,328 m
The length, the height and thickness are crap of course but take a look at the volume and area...


An Autodesk employee told me that because of the time to market during development of the first version of revit that they had choosen the imperial system. Please you have had enough time by now to fix this.

it's fixable if you change the export options. But still, it's awkward

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Thursday, 5 January 2012

Model review part 2 - Walls

This blog is about evaluating a revit file with the tools I got at my disposal

The goal is to find those objects that Revit users have done wrong or are inadequate. The tools I will use are:
  1. The warning system in Revit (WSR)
  2. The Autodesk Revit model review extension (RMR)
  3. Navisworks (NWS)
Errors to find:
1. Walls overlapping
2. Duplicate walls
3. Walls smaller than 1 meter high and higher than 5 meter

I tried running these tools on a real project from a client but these gave so much feedback that it was hell to sift through.

So I started with an empty project so I can create the errors in a controlled manor. I want to be able to automatically find those with the tools mentioned above.

As the title suggest lets start with walls. Below you see 3 walls in Revit and the same 3 walls in Navisworks.
Error 1:

1. WSR finds this error
2. RMR does not find the duplicate wall
3. NWS finds it as a clash but in order to find it you have to set the clash in such a way that every wall join registers as a clash. (It would be great if anyone had some tips)

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Model review part 1

A client recently came to me with the question how he could asses the quality of a Revit model. Having much experience with Revit myself I like to think I can quickly evaluate the quality of a model. The problem is of course that this is personal experience which can not be easily transferred to someone else.

Talking about Revit files there are a lot of indicators that trigger me to further investigate the model.

Project fase
First question I tend to ask is what phase is the project file in. Early design and so. 

File size
Before opening a project I take a look at the file size. File size is not a good indicator to judge a project on but we are looking for something out of the ordinary. There is a relationship between project phase, project size (m² ) and file size (Mb). You can't put hard numbers on this but after having seen many Revit projects you will notice when things are off.

Big tip for everyone! After opening a project go to the warnings!!! Tab: Manage on the right side. If it's grey, rejoice! If not, be in for a 'treat' click on it and take a look. Next I have copied a couple of warnings from a file I recently received:

1  There are identical instances in the same place. This will result in double counting in schedules...
2  A wall and a room separation line overlap. One of them may be ignored when Revit finds room boundaries. Shorten or  delete the room separation line to remove the overlap...
3  Highlighted walls overlap. One of them may be ignored when Revit finds room boundaries. Use Cut Geometry to embed one wall within the other...
4  Insert conflicts with joined Wall.
5  Top reference is below Bottom reference for one or more Balusters. These Balusters are not created.
6  Elements have duplicate 'Number' values. 

Some of these errors are more severe than others and some maybe be ignored for the time being. (they will need to be solved sometime) Error 1 was an extremely severe one. When I expanded it, it gave me 3400 errors... 
The only nice thing about this number is that my job was immediately done. I could tell the client that unless the modeler fixes these errors this model is completely unusable.    

Project Browser
Next have a scroll around in the project browser and see how everything is organized. I look for how the views and sheets are ordered. If that is neatly done you will know that the user(s) working on this file probably know more about Revit than just the basics. 

A good indication is taking a look at families in the project browser. Look at the names used for families and types. If I see a consistent pattern, something that clearly indicates a naming system, I tend to smile. The use of a naming system gives me an indication that the modeller knows that no system leads to chaos.

A lot of content builders put the company's initials in the family names. If I see a lot of different initials I tend to ask whether the have worked on this project with different companies. If yes I asked for the names of the companies if no I tend to worry a little because it can mean they have put this model together with content from everywhere. Mixing different content builders tends to give interesting effects....

3D view
Next I open the default 3D view to take a look around and get a feel for the model. I orbit around and zoom a bit. Basically I check the performance of the machine running Revit. Looking at the file size and the computer specs I know what kind of performance I should be allowed to expect. If it's slower than expected it can be an indication that the project is polluted with performance degrading thingies. This tends to worry me a lot. Most Revit users I help come from Autocad. Some users tend to keep Autocadding (a verb I made up) in Revit. This is a very bad thing! Autocad is performance wise rather forgiving for crappy drawings. Lines on top of eachother in Autocad do not have to cause any trouble. Walls in the same place in Revit is a recipy for all kinds of mayhem.

A simple thing to do is turning on and of categories and see what shows up. 

The next things I check are:
I take a look at anything that catches my eyes. Your are looking for things out of the ordinary positive or negative. Anything here gives you an idea of the knowledge of the user or the level of organization of the company he works for. Although the question is of course evaluating the model a lot of the things I look at also evaluate the modeler. 

The manage links dialog box
How many dwgs or other files are linked in.

Object styles
What kind of subcategories have been added. A nice one to spot is the obviously double ones but are named differently.

Imported objects
If it's clean, good if not just take a look at how much it is.

Material editor
Organization!!! Neatly organized materials tends to mean a structured approach to information modelling which is a good sign.

Purge unused
I start up this tool not to purge the project myself but merely to seen how much content is in the project and is not being used. It does not have to be zero but it shouldn't be a couple of thousands either. Don't purge for the sake of purging but do clean up stuff you are not going to use.  

Line patterns
Look for Autocad linestyles, the fewer the better

Level of detail
open some views and change the level of detail. If nothing changes besides the one build-in by the factory it could be another indication of less knowledge of Revit.

View templates
The use of view templates gives an indication how well organized the modeler is and the level of experience. 

Other things to look at to give you an idea of the knowledge of the user would be coordinates, design options, phasing worksets and revisions

It seems like a lot of things to look at but these are all meant to be glanced over at first and to give you an impression of the model. 

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