Importing CAD Files and By Shared Coordinates

When we link/import DWG files with survey data Revit often encounters file extents that are quite large. The developers have always encouraged us to use the Auto - Center to Center positioning option with those files. Revit will forcefully use that option when the extents of the file violate the current 20 mile tolerance it has.

I wish I could write that linking/importing survey files was very simple and error free. The reality couldn't be further from that. I recommend these steps to improve the odds for success:

• Import multiple Survey files individually (don't nest them as xref's)
• Purge everything you don't need, purge again
• Use Wblock if you can't get Zoom Extents to focus on just the relevant portion of the site
• Remove Named UCS (Revit only wants the World Coordinate System)
• Set UCS (User Coordinate System) to WCS and Plan to WCS
• If the survey isn't oriented to WCS, North is "up", have the civil engineer/surveyor change their file first
• Identify a specific location within the relevant part of the survey, put a marker, identify its coordinates, better still make those coordinates easy to use, even clean numbers.
• Make sure everything actually aligns correctly in AutoCAD first, no point setting it up in Revit if it doesn't work there
• Once you get a working first survey file, pass it back to the surveyor so they know what you need in the future

Once we've used Acquire Coordinates on our first survey file and verified the resulting coordinates are correct we can import the rest of the site related files. If Acquire Coordinates didn't work then we need revisit the items above, especially Named UCS. I find that Revit will acquire very large coordinates accurately IF the file is pristine.

In contrast I also like to use Specify Coordinates at Point (SCaP), using the marker I created earlier. Keeping in mind that doing so doesn't establish a shared coordinate relationship between the CAD file and the project. By relationship I mean that Revit records the identity of the linked file in the project when/if Acquire Coordinates is used to align the project with the linked file's WCS origin. SCaP does not.

Now regarding the title of this post, importing the rest of the files. Once shared coordinates are defined based on our first file we can import other site files using the positioning option: by Shared Coordinates. This assumes that each of the site related files are already aligned with each other using the same WCS origin. When we link a file this way a warning will appear while it is loading.

Revit is being precise, warning us that this project doesn't have a shared coordinate relationship with the incoming file. That's true, it is just another CAD file as far as this project is concerned. The only shared coordinate relationship that is established is between the first file and this project.

The last part of the warning is the significant part, The link's World coordinates will be aligned with this project's Shared coordinates". That means it will line up correctly because our project is aligned with the same WCS and both cad files already use the same WCS origin between themselves. Clicking Close accepts the warning and the link should land in the correct location. We can repeat this as many times as we have site related files to use.

When we save our project we may receive this warning. In this circumstance choose the bottom option Disable shared positioning...

We really don't want to create a named UCS in the CAD file the dialog references. It's linked and lined up correctly, its WCS is already correct, there is nothing to be gained by letting Revit store a named UCS in the file. This is what happens if you click Save instead, we end up with the named UCS in the image below.

I don't recall Revit bringing up this dialog in the past, unless I moved the link later, and I don't think it should be doing it in this circumstance. Fwiw, it doesn't in Revit 2015, at least not with the files I've been experimenting with for this post. It may be related to having a Named UCS. In some further testing I was able to link and save without generating the dialog. The inconsistency seems to consistently fall back on the condition of the DWG file though.

If we are careful to link each file and Disable the shared positioning Revit seems to think needs to be established all our linked file should line up very nicely. When they don't I find it necessary to revisit the list above. Skipping over them is very likely to bring on heartache later.

Property Lines without Digital Reference

As a follow up to a related post last week this post describes how we can create a property line when we lack any digital data to use. The survey may be an old hand drawn document provided as part of the deed or it could just be a printed drawing that nobody can find the file for. While we wait for a new survey we can still start with what we have. We've captured some bearing and distance information from my old survey drawing.

When we have a CAD file we can import as a resource the Property Line tool option: Create by Sketching makes it pretty easy. Since that's not an option in this situation we need to choose the other option: Create by entering distances and bearing.

Take a moment to revise the project units so they show the same units as the survey data. It helps to confirm the values we see in the dialog match those we've entered (it's shown that way in the image, not in the video). When we enter values for bearing a space between Degrees, Minutes and Seconds is all that's needed. To advance from one field to another we can use the TAB key to move forward or SHIFT + TAB to move backward in the dialog.

Also note that if the distance and bearing information is accurate enough Revit will report "closed". If the data isn't then it won't be able to report "closed" or show the area of the property. Unlike many sketch based elements Revit will tolerate a Property Line boundary that does not close. I altered the distance for the last segment to show the following error message that appears.

Once the Property Line is completed, click OK and we'll find the element is "stuck" to our cursor expecting us to decide where to place it. We pick an arbitrary spot and then move it so a corner of the Property Line is at a corner of the building. The goal is to make it easy to use Rotate True North and define the angle between the current Project North position of the building and the side of the property we'd like it to line up with.

In this example we've decided that the side of the house needs to be parallel to the East property boundary segment. Now we can use Rotate True North. When the tool starts we need to choose where the Rotation origin should go. In this case we need it to be at the corner of the building, the same corner where the corner of the Property Line is now. The first pick is rotation origin, the second pick is on the building and third pick is on the property line segment.

The task is much easier when we put the Property Line right on top of the building as a frame of reference. It also allows us to define the angle without trying to determine what it actually is.

Now that the orientation is correct we can move the Property Line into the correct location/position. Adding dimensions makes it easier to be accurate. We need to double check the values to make sure the changes to one dimensional direction don't alter other dimensions inappropriately.

This is a video demonstration of the concepts with captions, no audio.

Point Known - Build Your Model as you Measure

PKNail is software that is being developed by PointKnown Building Solutions. The purpose of the software is to improve the process of measuring existing buildings and then building a model using Revit.

It's based upon using the Leica Disto D8 surveying tool.

The software is not yet commercially available but I just received an email that shares a video (posted at YouTube) that demonstrates how it works. It is a little over 8 minutes long. If you've ever measured an existing building you might want to spend 8 minutes and watch. Jim Foster is the person doing the demo and he has a blog called BIM, the Built Environment and Stuff. I've embedded the YouTube video here if you want to listen to it now. I recommend watching it full screen though.

BIM Support Survey and Blogger Profile

I posted a notice about a BIM support survey that Jason wanted to do back on February 24, 2010. He has since wrapped up the survey and written it up in a fourteen page report. He really did a nice job putting it together and it is well worth your time to download it and check it out.

Who is Jason Grant?
Jason is the BIM Specialist at Payette in Boston, MA. His experience includes over 14 years in the architecture field, 5 years of Revit use on 62 projects at Colin Smith Architecture and 2 years managing Revit implementation, training, standards, API and content development at Payette. With his Revit experience including Healthcare, Labs, Commercial, Mixed-Use and Residential, he understands the challenges that both small and large projects face while utilizing and implementing Revit. Jason is also Co-Founder and Advisor to the Boston Revit Users Group with 200+ members, Co-Founder and Co-Leader of the BLUR Group (BIM Leaders Utilizing Revit), author for AUGI | AEC EDGE and an avid blogger on BIM and Architecture.

Survey Results - Revit Sweet

Thank to those of you who took time to vote in my quiet little polls! I appreciate the votes and I'll take them to Autodesk with the hope that they will consider it more seriously.

The results of the surveys I posted are: (poll was open to voting for 30 days)

Want a Revit "Sweet"? (156 votes)
115 - Want a Revit Sweet bundle/combo (73%)
24 - Want just two out of three versions (15%)
17 - Only need or want one version of Revit (10%)

Willing to pay how much? (110 votes)
1 - 15k full price basically (0%)
25 - 9.5 k (price of two versions) (22%)
13 - 7.5k (a bit less than two versions) (11%)
71 - 5K plus higher subscription rate (price of one version but willing to pay higher "freight" per month for the additional features) (64%)

Just to clarify it was my intention that this poll reflect the delivery of a "All in One" product, all Revit tools and features combined into one product, one install, one product code. Not the delivery of three separate products for a special price though nobody would object to special pricing for purchasing all three versions at a time. The ideal situation is simpler price, simpler installation, simpler management...one product, one install...all the features.

Background: There are between 300 and 600 readers of this blog visitors per day during the week and it drops to between 100 to 200 on the weekend. I assume most are repeat visitors so this means that roughly a quarter of the readership chose to vote.

My conclusion? A majority of users would like to have Revit "Sweet" and are willing to pay more through their subscription rate to get it. I wasn't surprised by the results for wanting Revit "Sweet" but was a little surprised by the willingness to pay more for subscription as opposed to the 3 for 2 pricing approach. I suppose the assumption is that they'd pay less via subscription somehow.

I hope that Autodesk does some measuring of the market themselves and finds this approach to the delivery of Revit and its toolset to be consistent with my results! They couldn't deliver Revit "Sweet" fast enough for me and most of the clients I visit.

Revit User Survey

David Conant posted THIS at AUGI requesting that Revit users contact him to receive a link to a survey. David wrote this:

As part of our effort to understand users’ actual experience, the Revit product design team occasionally conducts surveys on specific aspects of Revit’s interface and behavior. If you would like to help our efforts and take a short survey on your experiences, please EMAIL ME and I will send you a link to the survey.


Clicking the EMAIL ME link will probably only work if you are already logged into AUGI...your mileage may vary. Your best bet is to follow the THIS at AUGI.

If you remember my survey post awhile ago at least this request is up to you or me to choose to get involved.

CAD Surveys and your Revit Project

This text was posted at AUGI by David Conant (Autodesk Revit Product Designer) in February this year. It is very important information.

This method should ALWAYS be followed. It is critical to follow when the survey coordinates of your building site have large values (> 2 miles/3km from site 0,0):

ALWAYS locate sites underneath buildings. Revit buildings like to stay near home and be oriented to project north. Sites can wander about and talk to the buildings later. DON'T try to pan your view 40 km northeast of 0,0 and try to build your building model there because your site coordinates have a remote origin. This will work in AutoCAD but in Revit you will be very unhappy.

NEVER import or link a site with large coordinate values Origin to Origin! This may seem correct based on AutoCAD experience, but here too you will be very unhappy in Revit. You will get the correct origin later in the process.

• Build your revit model at or near the position of the elevation marks in the default template with the building oriented orthagonal to your desired printing frame. i.e. use a Project North not True North for your working environment.

For one building on a site:

• Link in a site model or site dwg.
• Move and Rotate the SITE so that it is located correctly relative to the building.
• Acquire the site's coordinates. Now, the site's origin will be the origin of your shared coordinates. The site's Y axis will be True North. The site coordinate values can be arbitrarily large without disturbing Revit's internal calculations.
• You can later open the site model and link in the building using shared location and it will land in the exact position.

For multiple buildings on a site:

• Create a Site project, link in a site dwg, placing the center of the building site near the center of the default view.
• Acquire coordinates from the site.
• Build any site elements, topos, etc.
• Link in building rvts. Move and rotate them so that they are correctly located on the site.
• Publish coordinates to the rvts. Now all models will have the same Shared origin and True North orientations.
• You can now link the site into any of the buildings (the other buildings can be linked in as well) using shared location and it will be in the exact location.