Import CAD - Orient to View

This is what the Autodesk Help documentation says about this feature at the moment.

Orient to View - This option is useful if True North and Project North are not aligned in your Revit project. If True North and Project North are defined identically in the project, then this option will not affect the way the import/link is oriented. The World Coordinate System (WCS) is used to orient the CAD file in the view.

If the current view is set to True North and True North is rotated away from Project North, then clear this option to align the CAD file with True North. If you select this option, the CAD file will align with Project North regardless of the view orientation. Note: CAD files are always imported into the current view from the top view direction. The CAD file is brought into the view assuming that the current view is a top view.

It also does something important or relevant when importing into elevation or section views. When people draw sections and elevations in CAD they are often doing so in the plan orientation of the file. It isn't all that common to see people reorienting their view in AutoCAD and then drawing those views oriented to Front or Back etc.

When we select this option and import such a file into a Revit elevation or section view it will rotate the plan of the CAD file into alignment with the section or elevation view. If not then the imported CAD file is aligned with the plan orientation of plan views and we only see the edge of the files lines in the elevation or section view.

If the option Current View Only is chosen then this On by default

Importing AutoCAD File Fails

When you try to import AutoCAD data you might have seen this series of messages before? First we get a complaint about Elements lost during import.

If it is a Civil3D file that might not be too surprising if they created AEC elements like contours or road elements. Then we get this message.

It's especially confusing if you just were looking at the file in AutoCAD and know there are elements there. Worse you'll probably see the first dialog again if there isn't any data in Paper Space to import either. Even worse is when you find out it is all "your" fault. Well at least in this case it was my fault.

The culprit is saving the DWG file and then attempting to import that DWG file, which happens to be using a newer format than the version of Revit that is being used. In my case it was a AutoCAD 2013 file that I was attempting to open in Revit Architecture 2012. I keep forgetting to save it using the 2010 format. Once the file is saved in a compatible format Revit works much better. Too bad the messages don't give you any clue it is a version thing.

So if you see such messages remember it might just be the file format/version.

Extents Greater than 20 Miles

This message appears when you import a DWG file that has geometry that makes the total extents of the file larger than 20 (33 km)miles horizontally or vertically.

That message is different from this message.

The second message occurs when all the geometry in the file is farther away from the origin than Revit wants it to be, but the extent of geometry is not large enough to trigger the first warning. What that magical distance or number is, who knows. I've spent quite a bit of time trying to pin that down. The closest I've come is that when I have some geometry that is between 43,500 and 50,000 feet away from the origin of the DWG file Revit will complain. The problem with pinning it down is that as soon as I think I've got it, I change it a little and then Revit doesn't complain about importing the file. Suffice it to say that if all the geometry is pretty far away from the origin, there is a pretty good chance that you'll see that message. It isn't as far away as the first error message though (20 miles), it's more like 8ish miles.

If a file is too large to import when you've selected the correct units you can technically circumvent it by importing with different units. For example if Inches are too big, try Feet. The file will like import. Then you can reset the Units of the file and reset the scale value to 1. The file will be the correct size again. It won't prevent the graphical issues that really large DWG import can cause though. Your mileage may vary.

Another technique that has worked is to link the big file into another file as an Attached overlay. Then import the file that hosts the big one. Revit doesn't look at the Xref and doesn't complain.

Point Cloud Data into Navisworks

Navisworks supports Leica (.pts .ptx) and FARO (.fls .fws .iQscan, iQmod, iQwsp) scan data formats as well as ASCII text formats (.txt .asc). I received a tweeted message the other day asking about getting the point cloud information from a Photofly session that resulted in .las and .pcg files instead.

Navisworks hasn't caught up with the recent addition of the .pcg indexed file format that AutoCAD and Revit use. It's a case of unfortunate development timing. It means that we can use .pcg files in Revit but we can't use the same files appended to a Navisworks session, we have to use something else. I've been starting with .pts files, creating the .pcg for Revit and then using the .pts in Navisworks. Your head hurt yet?

My suggestion to the twitter member was to import the .pcg file into AutoCAD and then Append that file into Navisworks. Navisworks will index the point cloud data when it reads the .dwg so you get the data despite the "unfamiliar" format. A workaround at best, but workarounds that work, work for me!