DWG Files and Funky Snapping

Importing survey files has always been problematic with Revit. Two things are fundamental issues: large file extents and distance from origin.

Geometry that is far apart will annoy Revit, geometry more than 20 miles in extents is the current "line in the sand". Just how precise this 20 mile consideration is a little hard to pin down. There must be some specific logic or algorithm the application uses but I've tried numerous times without success to arrive at something consistently true.

For example I've tried to draw squares and cubes, even circles and spheres to test the extremes and predict the trigger of the error messages I've written about before. As soon as I think I have something I can predict I try it again and get a slightly different result. My general rule of thumb is to try hard to make sure that I don't have extents that exceed a sphere that is 20 miles in diameter.

The other issue is when the data in the CAD file is small enough in extents but really far away from the file's origin, according to the WCS which is all Revit really pays any attention to. I can have a relatively small project site survey but far from origin and end up with Revit using Auto - Center to Center to place it. That's not really a problem though. We can just tell Revit how to resolve that with the Specify Coordinates at Point tool.

Now as for the title of this post, Revit hollers when our file is "too big". The warning tells us that this situation may affect the graphic depiction of information on screen.

This manifests itself in snap icons that appear to miss the element we are attempting to reference in the CAD file. It also shows up when you use the Pick tool to place lines and the sensitivity of the tool seems offset somewhat from where we see the line.

With Revit 2013 they've added an option in the Import dialog that says "Correct lines that are slightly off axis". This is a bit of spin unfortunately because this addition means it acknowledges that Revit has been altering them before, all along. Part of the solution to the funky snapping is resolved with 2013, don't check this option.

With Revit 2012 we can still avoid it but we have to import the DWG files a little differently. The trick is to let Revit place them using Auto - Center to Center and then move files, however many you need to use, into place manually. If we try to use the trick to Specify Coordinates using one file first and then import the rest using "Auto - by Shared Coordinates" it will trigger something internally that in turn triggers the snapping issue. That trick generates a message that these files aren't sharing coordinates but the end result is that they land in the correct location because shared coordinates are matching their own understanding of the WCS.

Here's a summary of steps, sort of...

Examine your survey file and make sure it isn't too large.

If it is you need to reduce it so just the really relevant part of the site is what you import. I realize that there may be situations that challenge this assumption but if you create two files from one that provides two that are small enough to avoid the error message about extents then you can still bring them in, position them manually and then specific coordinates.

Once you've resolved the survey file checking, pick a spot in each file that can be used as a common reference benchmark. You'll need it to move them into position in Revit. Write down what the coordinates are for this benchmark.

Now you can import the files into Revit. Use the Auto - Center to Center option. In Revit 2013 don't check the "Correct lines" option. You don't have this option in 2012 but this process will still work.

Move the files into position keeping them all near the Revit project file origin. Now you can use the Specify Coordinates at Point (SCaP) tool to match up Revit with your benchmark in the cad file. Unclip the Survey Point and move it to the benchmark location. Fire up the SCaP tool and enter the matching coordinate values.

Revit now understands your real world situation. You should find that snapping to the imported file elements is not showing the graphical glitch.

Important, there is one more thing to avoid, don't create a master survey file that uses attached Xref's to combine several files together into a single file that gets imported into Revit. Doing this will trigger the snapping issue again. It does it in 2012 and 2013 regardless. I believe that the Xref's mark the origin somehow in the master file which creates an unavoidable file extents problem which brings the snapping issue back to life.

Easy?? Wish it were easier!

Room Separation Lines - Agida for MEP?

Via email the other night, he writes...(edited a little)

We use Revit MEP. I’m doing some research on Room separation lines, as to how and why architects use them, and when is appropriate. The problem I am consistently running into is that room separation lines divide spaces as well. These divisions, while relevant to the architectural model, are ruining the possibilities of creating gbXML files without extensive work on the part of the engineer to remove the room separation lines, and then repair the damage done to the room names and numbers.

For example, imagine open library stacks with dedicated study areas. In the architectural file, they used room separation lines as a rectangle to create rooms and tags for these study areas. They were also used to define a corridor along one side of the stacks (but still in the same open area). For MEP these are really all part of one big room. We won't need to add dedicated air terminals to these areas, nor special lighting just for these areas. So any of the analysis tools in Revit using spaces will be wrong, as most of them use an average over the entire area, (CFM/SF, Average illumination levels/SF etc..). Further, we are unable to accurately or efficiently create a gbXML file for use in Green Building Studio, HAP, Trace, etc. This complication is greatly hampering many of the benefits of using Revit for engineers.

I’m not saying that room separation lines should never be used, there are perfectly good places to use them. Rooms or spaces that are actually going to be treated as a separate room, not a room with in a room.

I initially thought that architects were using these (in addition to the obvious) to check for programming requirements, and code compliance for areas and such but it turns out a lot of architects are using the area tool for those purposes. They were however using them for the room finish schedules.

From a program standpoint, I was surprised to find out that while room separation lines can be assigned to a workset and that workset can be unloaded (through a linked file) from the MEP model. However the Room Separations still existed. We just couldn’t see them. And even if that did work, we engineers would still need to correct/edit the space names and numbers manually now since the spaces wouldn’t match the rooms (Space naming tool wouldn't work).

He closed wondering if I could offer any advice, ideas or a solution.

The essence of my response via email:

HVAC Zones are meant to combine spaces into larger more coherent collections for engineering purposes. The example given above for the library is pretty common place, need to know how much area is dedicated to carrels as well as a corridor within the open space of the library. From the HVAC engineer's perspective irrelevant but not from the client's or the architect trying to satisfy them.

If room separation lines are "off the table" then the architect would end up using something else like actual walls and hiding them. They might end up asking Autodesk to make more elements room defining? Area plans could help document such things but then floor plans would be "ignorant" of what these kinds of "areas" are, no tagging possible, just "dumb text". Not ideal either. My greatest concern about room separation lines is when they are used as "band-aids" to try to fix room area issues, where rooms aren't bounded properly and not generating area values.

Regarding the workset comments. Worksets unload information but that doesn't mean Revit isn't aware of the elements that are assigned to the unloaded workset. When we unload a workset the walls are still there and that means so are Room Separation lines.

Any comments from readers??

Measure Between Two References

Saw a post at Revitforum.org asking how best to go about finding out what the perimeter of a given building is. I was a little late to the party there and I was mulling over what to write about tonight...

The catch, the building is a linked file. Not much of a catch but there is no equivalent floor in this case. If there was a floor there I'd just check the properties of the floor. Technically if a linked floor matched the perimeter of the building you can still see properties of the linked element if you use the TAB select technique to grab a hold of the element in the link.

...or you could sketch your own a floor around the perimeter pretty quickly. or you could use the area tools. or you could draw a property line. or you could....

Use the Measure Between Two Reference (MbTR) AND check the Chain Option! This will give you a running total as you pick additional points along the perimeter of the building. Here's a quick video demo.

For my money, I'd probably favor a floor. That way when the person who asked you to find out says something like this, "Hey what was that perimeter value again? Sorry I didn't write it down" You can just check the properties of the floor instead of using MbTR again, or flinging your scale at them.

Detail Level Ignored with Unlocked Wall Layers

We can unlock a layer or layers in a wall to allow "pulling" them up or down separately from the rest of a wall. This makes it possible to create a brick veneer that drops below a level some distance or pull the stud layer up farther, like this.

To make this possible you need to edit the wall's structure and select a layer to unlock, like this: 1 - Click Modify, 2 - Select the edge of a layer, 3 - Unlock the padlock

Interestingly, in Ceiling Plan views only, when we take advantage of this we lose the ability to show just two lines with Detail Level: Coarse.

I suppose it makes sense somewhat, since they are now distinctly separate but the hope was that we could still see just two line in Coarse. Seems to work fine in plan views though.

Revit MEP Electrical Calculations

Martin Schmid has been sharing some deeper insight into the "magic" behind electrical calculations that Revit provides. Every engineer I've met is, not too surprisingly, skeptical about trusting yet another software for these answers. There has been data, in help documentation, to support the results but not quite as deeply as the last three posts combined. Check them out!

Why do I get different Voltage Drop results with Revit compared to the NEC?
To compute Voltage Drop, why does Revit use the formula VD=(L*R*I)/1000?
Why does the Revit Wire Impedance Factor table have separate sections for Three Phase and Single Phase?

RTCAUS Wrapped for Another Year

I was busy pretending to be @RTCAUS on Twitter during the conference. I also wrote a few things during the conference on the blog for RTC. Those two alter egos provide ample distraction from this blog unfortunately. Between the attending of sessions, the socializing, committee member roles etc... I just didn't have enough brain cells left over to post here too. I hope to be able to resume being just me again soon!

The conference went very smoothly. Well there was the elevator needing a part from Germany. There was the internet service provider playing havoc with my "mello" but for the most part it really went swimmingly!

Ralph Grabowski attended the conference this year and wrote several articles about the event on his blog "World CAD Access". If you don't follow his blogging I encourage you to consider doing so. He's been deeply involved in following this "biddness" we are in, from a technology perspective at least. All for now, check out Ralph's post for some insight. You can also review the Tweets and the pictures that were part of many of them. I'll be posting pictures and info on the Facebook site in the coming weeks too.

View Reference Origin Location

I observed this the other day which remind me that it bothered me in the past but failed to bring it up before. The View Reference family that we can use in conjunction with Matchlines and now with Revit 2013 to create more general reference to views on sheets has an unpleasant effect on views that they are in.

They are assigned to the View Reference category but fundamentally began as a generic annotation family. When you create one from scratch or just edit the one the comes with Revit templates you'll find something like this.

The Move icon ends up very far away from the symbol itself when it is in view that are using finer scales. In a view that is assigned to something like 1/8"=1'-0" it is closer to the symbol. The downer about this offset is that it increases the "size" of the viewport when the view is added to a sheet. It just creates some unnecessary busy work to adjust views when this happens. If you find a viewport becoming "larger" than it should it might be related to this kind of situation.

Revit Technology Conference AUS 2012 is Underway!

This post is playing time traveler, dropping back in time to Monday (May 22). I was on a United 747-400 heading to Sydney when Monday happened at home in the USA. A curious side effect of travel west to Australia is you lose a day. Sydney is 17 hours ahead of the west coast of the USA. So when I boarded my flight on Sunday night at 9:45 PM it was already 2:45 PM in Sydney, but tomorrow (Monday). By the time I landed in Sydney Monday already turned into Tuesday morning. This means I lost Monday, missed my son Jake's birthday and didn't post anything here. I could have set something up to post while I was traveling but that would mean I was better prepared, I wasn't. I digress...

It's that time of year again, RTC is here. First up is the conference in Wollongong (aka The Gong and 90 minutes SE of Sydney). VisDay is a new event focused on visualization technology. The Chairman is Dan Jurgens and he's worked hard to assemble a quality group of presentations. The RTC conference begins on Thursday May 24th and VisDay is the "warm up" act, to use a concert metaphor. VisDay gathers (gathered) on Wednesday May 23rd. Writing about what will happen when it just happened is a bit odd...

Tonight I'm polishing my presentation about What's New in Revit Architecture 2013. Each year I feel like there isn't enough new stuff to make me happy. Then I write up this presentation and I find it takes a lot of effort to scratch the surface in a modest way. This year is no different. There are some big ticket items that attract attention but there a numerous other and more subtle features that contribute to a fairly long list of things to speak about. That will happen just after lunch on Thursday May 24th (tomorrow as I write this).

The event in Australia is upon us. You can still attend technically, assuming you can (a) get here, (b) make the time and (c) act fast!! Join the 400 or so others revving up for three days of Revit and BIM technical sessions and discussions.

There is just over a month until the RTCUSA starts in Stone Mountain, GA on June 28-30, 2012. Don't miss it!

Revit 2013 - Double Click a View Reference

I wrote about the enhancements to the existing View Reference feature in March when the software first was released.

I didn't mention this other little goody, for people working inside Revit. If you double click on the view reference family Revit will open the view! If you export to DWF and export all the sheets to the same file you'll find they behave just like other annotation for views, CTRL + Click will open the other sheet/view.

Selecting Multiple Saved Selection Sets

Sibilance! I used to work for Syracuse Scenery & Stage Lighting, Co. in Syracuse, NY. It was fun when I had to introduce myself formally starting with, "Hi, I'm Steve Stafford with...". The title of this post reminded me of that, sorry! I was going to lead into it with Dept. of Subtle but that was too many "sssss"... it is really subtle though. Okay I'll get to it then.

Revit 2013 added Saved Selection Sets, a feature that was part of an extension for Revit Structure originally.

The concept is simple, select elements and click a button to save (top button in the image above) them as a set that can be called on later, to do something with or to them again. If that seems likely then it will come in handy. The Save button wakes up when there is something selected. The Load button wakes up after something has been saved as a selection set.

The subtle part of this is that when there are several selection sets to choose from, what if we want to do something to more than one at a time? The dialog doesn't let us select multiple saved sets. Guess we're sunk.

[Edited 5/18/2012 - Gabe pointed out in a comment that CTRL isn't necessary, just running the tool again by clicking Load will allow us to add another selection set, cool! Thanks Gabe! - Disregard the following section]

It doesn't look like it will work but using the CTRL key does work, just not inside the dialog. The trick to this is selecting one and clicking OK to leave the dialog. Then press CTRL and click the Load button again (middle button in the first image), select another saved set, click OK.

Now we've got two saved selection sets selected again. It's easy when you know how!

Apply View Template to all Views

I don't recall when this first showed up but I noticed it first in Revit 2012. Here's what it looks like with a right-click in Revit 2013.

My first reaction was cool! Then I wondered, "When or why would I use it?". Pondered it for a bit and decided that it might be cool if I have a sheet full of details that needed some cleanup. Create a view template and then apply it right quick. Then again I could just select multiple views in the project browser and apply them. With Revit 2013 my view templates will adjust all those details as soon as I change the template, or at least they can if I set it up that way. I suppose this feature might be handy if I forgot to do it and they were all on sheets at this point.

A subtle refinement to process that probably just goes unnoticed? I wonder how many of my readers use it, know about it, care?

Revit 2013 - View Types

It is now possible to create new view types for all views except for area plans and sheet. This means you can create your own versions of floor plans according to discipline or perhaps design phase. We've been able to do this with sections, elevations and detail views for some time. As Revit's features have been merged into the new Building Design Suite "Revit" it became apparent that putting all the tools in one box created some curious view, view template and discipline control issues that had to be sorted out, thus being able to create view types for more views was born.

Further, views can be tied to view templates and have changes to a view template take effect immediately in a view or many views. We can apply a view template like before, just to make a change or we can assign a view template to the view so that it will alter the view without the past extra step of applying the view template. This is the typical assumed behavior that most people where surprised to learn did not happen in the past.

One curious thing that is documented at the WikiHelp site regarding these new view types, changing a view from one type to another does not actually apply the view template change that is assigned (if any) to the view. It is an instance parameter so it's an extra step you've got to take to make sure the view has the correct template assigned.

If you use the Apply View template option on a view assigned to view template already you'll get this message.

It's confirming that you really want to apply a different template's settings to the view. It also says that the only properties that will be altered are those that aren't in conflict with the other template. Hopefully the swapping of view types won't occur much after creating them initially and getting this sorted out. If you do find yourself needing to swap them around, just remember to check the view template assignment.

Tip: They've added View Template to the available fields in View Lists (schedule) so it can be managed there too.

Dept. of Echo - Don't use the Basic Ceiling

Originally posted here August 2009 and still true with Revit 2013

When an architect uses the Basic Ceiling-Generic type they are creating a situation for the Revit MEP user they may not be aware of. Face based content does not orient themselves to the correct side or face of this ceiling. For air terminals and others this means they are usually upside-down. I created a short video to demonstrate what I'm writing about.

You can listen and watch below:

Here's an image to convey the issue without watching the video. The left side is a Basic Ceiling and the air terminals are upside down. The right side is the Compound Ceiling and the air terminals are okay.

Hide Those Connectors

A recent question at Revitforum.org asked about hiding the connectors in family content for the sake of cleaner previews.

To accomplish this:

• In the view you want to use as the preview
• Select the connectors
• Click Temporary Hide/Isolate
• Choose Hide Element
• Save the file
• Close the file

BIM Coordinator for Civil 3D and Revit

Autodesk Labs posted an application that was developed by Autodesk Consulting. You can read more information HERE.

It functions as a plug-in that is installed in both applications, Civil 3D and Revit. It allows a Civil 3D user to define the shared coordinate system to be passed on to a Revit project. Running the tool in Civil 3D is based on selecting two points on a reference building footprint file (don't forget paying attention to elevation) and saving the information to a separate file.

Note that it uses a file formatted as ACCSXML (Autodesk Consulting Coordinate System eXtensible Markup Language).

The file is then used in combination with a plug-in tool inside Revit that asks you to pick the same points in Revit and then select the source file. As the project progresses, you can pass model data back and forth easily as long as you export by specifying the correct project units and Shared Coordinates each time.

You can watch a video at You Tube that explains how it works (9:53)

The process described assumes that the person deciding where the building goes is using Civil 3D which in my experience is not necessarily accurate. They'll ultimately be responsible or define it precisely eventually but the building location is often affected by a lot of things and roughed in by designers using an underlay of a survey and civil data.

It is also very important that the person using Civil 3D passes along the two key points on the building. If they get this wrong or we misunderstand them we’ll end up with a discrepancy when we potentially pick slightly different points. Of course this assumes that the civil engineer is not sitting right next to “us”, the architect or structural engineer. Connecting the information between all parties still boils down to someone deciding what building location is "spot on".

Check it out, might help your next project?

Should I Use Revit for this Project?

It isn't a surprising question, it's asked often. I wrote a post before called "Yeah but". That's the kind of response that often comes after answering the question with, "Yeah, you should".

"Yeah but... the architect isn't using Revit, the engineers aren't using Revit, we don't really need 3D for this project, this project doesn't have the margin, this project is fast track, this project isn't big enough, this project is too big"... and so on.

A recent one I heard was, "The architect isn't using Revit, should we use Revit MEP for this project?"

When Revit Systems was released in 2006, the essence of Autodesk's marketing commentary was, "this is new software so it probably doesn't make sense to tackle a project with it unless the architecture team is using Revit too." I don't think it is still true six years later. Sure we benefit from the modelling effort in architecture and structure but we can still benefit from the effort without them.

Is this our first project using Revit? - If yes, then maybe this project isn't the ideal first project.

Otherwise, assuming we are comfortable with Revit, then why not? Is it a valid question for architects? As in, "We aren't going to use Revit because the engineers are not using it." There wasn't a Revit Structure or MEP when Revit was introduced.

There is a lot more to Revit than just 3D. Why assume that there is no value in creating a model of the MEP scope of work even if the architect doesn't use Revit? We will still be able to compare our model against 2D documentation by importing various 2D CAD views into the model. We can still export to 2D files for them to do the same. Why assume that we won't learn anything from doing so? We don't have to assume the burden of modelling the architecture or structure to get something out of the effort. Every project has some, or more often many, surprises. Modeling a project reveals more than doing one in 2D. Just try creating a model using only 2D documents as the guide.

When considering this I think it is important to be careful which measuring stick is being used. Is it measured according to the technical drafting staff, the project engineer or manager, the firm, the project or the owner? If we measure too closely to who performs a single task we lose sight of the bigger picture, the downstream ramifications of our choices. Revit challenges our assumptions and process. More often than not I hear decisions being based on a notion of "us and them" in the equation. Adversarial business relationships don't make it easy to ensure a great result.

Given the chance, I'm betting that using Revit on any project (assuming some responsible preparation is in place) will ultimately prove to have been worthwhile, often in the least anticipated ways. I think this fits, "we don't know what we don't know". I find I stumble into what I don't know more often in 3D than in 2D.

Revit 2013 - Suppress Spaces in Dimensions

Revit 2013 changes the means to reduce the overall size of the text displayed in a dimension string, particularly noticeable to people using imperial units. It was tied to the project units and you had to alter a dimension style to not use the project units settings in order to use it.

This is the new location for the option, found in the Type Properties for a dimension style.

This means your dimension styles can continue to depend on the Project Units as well as suppress the spaces in dimension values. A subtle but more logical approach I think.

However in testing it appears to be broken... The option for Suppress Spaces exists in the the Project Units dialog. If I turn on the feature it affects dimension styles downstream and the option in the dimension style should then work as an option to remove it but it doesn't do anything. Odd...

Shared Coordinate Post Summary

Updated: 6/28/2023

This is a summary of posts I've written about shared coordinates and related posts. They are listed from the most recent to the oldest. That doesn't necessarily reflect their relevance based on age at all.

2023 Revit 2021.1 Reset Shared Coordinates
2018 Cannot Publish Coordinates

2017 Revit Coordinate Systems Video
2017 Linked DWG and Named UCS
2017 Clipped or Un-Clipped - That is the Question
2017 Shared Coordinates - Autodesk Reference Information
2017 20 Mile Threshold on Import
2017 Reset Shared Coordinates Update
2017 Revit 2018 GEO Reference and Shared Coordinates

2016 Publish Coordinates and Inter-related Linked Files
2016 BIM Workshop Sessions and Data
2016 Multi-Discipline Shared Coordinates
2016 Survey Point Values after using Publish Coordinates

2015 Revit 2016 R2 - Positioning by Auto - Project Base Point to Project Base Point
2015 Transparent Elevations and Large Coordinates
2015 Shared Coordinates and Collaboration for Revit
2015 Revit 2016 - Rotate Project North
2015 Link Positioning Manual - Base Point
2015 Survey Point - Post 4 - Acquiring Coordinates and View Orientation
2015 Survey Point - Post 3 - Five Minutes with Shared Coordinates
2015 Survey Point - Post 2
2015 Survey Point 1
2015 Follow Up - Importing DWG Files Using By Shared Coordinates
2015 Toposurface from a Text File
2015 Using Shared Coordinates - Do Not Remove the Link

2014 Importing CAD Files and By Shared Coordinates
2014 Relocate Project is Sleight of Hand
2014 Confirm Acquire Coordinates (wish)

2013 Basic Survey and Model Coordination
2013 Acquiring Coordinates between Trades
2013 Project Base Point Manipulation
2013 Transfer Project Standards and Shared Coordinates
2013 Moving the Project Base Point
2013 Coordinating Projects Using Shared Coordinates
2013 Lock Down Shared Coordinates

2012 Reset Shared Coordinates
2012 Revit Level and Elevations
2012 DWG Files and Funky Snapping

2011 Location Location Location
2011 Shared Coordinates and Copy Monitor
2011 Project Coordination - Early Days

2009 Autodesk University Virtual Shared Coordinates Class
2009 Shared Coordinates Features Disabled
2009 Starting Projects - Two Pieces of Advice

2008 Shared Coordinates and Other Trades
2008 CAD Surveys and your Revit Project
2008 Acquire Coordinates Confirm

2006 True Elevation and Position

Building Design Suite Installation Readme

If you are preparing for installing the 2013 Revit products via the Building Design Suites then you might want to start with the System Requirements PDF documents for each version.

Standard
Premium
Ultimate

You'll also want to read the Installation Overview and FAQ

Revit 2013 - Repeat and Divide Subtlety

For people experimenting with these new concepts and feature... I picked this item up recently.

If you are trying to make things work and running into problems make sure the Adaptive Component (AC) is hosted on nodes of a divided curve or divided surface. It can easily appear like its hosted correctly, but if you look closer you may find it is actually hosted to the curve, not the node. Also, if your AC family contains any Shape handles points, then it won’t repeat. All adaptive points in a family must be Placement points, not Shape Handle points or Reference points.

Read Andy's recent post about experimenting with them.