Doesnt suck at all. No way would i use someone elses model for Existing Conditions. Not without a billion *VIF* notes all over the entire thing, and a written clause about Add Services related to (and stemming from) Verifications that deviate the from the provided model, that create redesign requirements.

Amen, and Amen, and Amen. Depending on the job type and location I don't trust anything I haven't seen with my own eyes. Site work will bite you worse then most other errors I've seen on projects(pushing dirt around gets expensive really quick). Simple google earth overlay to survey drawing will probably reveal many missed elements that you may have to deal with. A site survey is one of the first things I ask for, then I overlay it with a google image(not saying the google is good to draw from, not at all) but you will see items that are "error and ommissions" and can ask about them. Now we have much better technology with our drones flying the sites for us, but the amount of man holes and trees or unknown poles you may find that aren't in the survey might be worth knowing about, they might not. As for the lines to draw, Aaron, as usual nailed them all. I'm starting a new very large job, I'm getting revit models of the existing structures, I've asked for the original 2d drawings that the project was built from because I don't even want to trust another persons revit model. I know that sucks, but we are still an industry in transition and much is missing in our 3d worlds that should be there that is still on the contract drawings.

Its actually quite simple: You draw the line at what they are contractually required to provide. Youll notice (in most cases) that ISNT the electronic files: Its the stamped, signed, document.

To be clear, im not suggesting you dont USE their survey (using surveys and tracing CAD drawings for buildings, is different). Sure, ill link in a civil/surveyors CAD file all day long.

Will i BLINDLY ASSUME they have the coordinates in the ELECTRONIC file correct? Not a chance in hell. In fact, i even tell my clients not to both using Acquire Coordinates. I go:

1. Link in their CAD file, and rotate/place it to match the building.
2. LOOK at their PDF or Paper Contract Document, and SEE what the True North Angle and Spot Coordinates are, at a fixed location.
3. Rotate True North manually, and Specify Coordinates At A Point Manually.

It doesnt take that much longer, and i almost never have bizarre issues with Coordinates.

This is so true. There is a massive problem (MASSIVE) where everyone *assumes* that other parties are always using their tools correctly, and that "everything we see in a CAD file or a 3D model is accurate and to scale." And folks dont mind fudging stuff and working NOT to scale, because they make people sign "disclaimers." I think people forget WHY those disclaimers exist. Certainly, even when we drew by hand, the documents were mostly to scale (except for things like flashing details and membrane diagrams). But the disclaimers were more about "You forgot this dimension, and you should give it to me so you can check that its correct in the drawing, and that the value it scales to is what you want me to use." But that somehow morphed in to "As a design team we dont have to be accurate," which is lousy.

I cant speak about other colleges, except where i went. But i can tell you (without any grey area) very little "practical drafting" is taught in Architecture school at all. They teach it at the Community Colleges, but in accredited Architecture Colleges, its a joke. They treat it as beneath them while they screw around with physical models and Ink on Mylar axon wall sections, and do stupid crap like that all semester long, while practicing making the studens all be sleep-deprived. LOL.

As horrible as this is, i actually teach folks (in all disciplines) how to CHECK if annotations are real or faked (text), especially on things like: Slopes, Coordinates, Spot Elevations, and so on. And the moment we find a faked dim or annotation, we place a real one right next to it. if they are different (by an amount that matters) you have to RFI it. But here is the part people forget:

If they are off by a small amount, the one thats FAKED is the one thats IN THE CONTRACT DOC. The fact that they make you sign a disclaimer before opening that electronic file, means (even though its what they DREW) using that instead of the faked written one puts you at risk.

Certainly, i rely on my consultants. I link in Structure, and MEP, and Civil/Surveying. I just dont Pick-Lines on their stuff to draw my stuff, and i dont *auto acquire* ANYTHING from their files.

Doesnt matter if its time intensive or not. Thats the game. :shrug:

So I'm curious, where does the line get drawn as to what I accept from my sub-contractors as correct?
I mean you/we have to draw the line somewhere, you can't do all the project yourself, at some point you rely on the competence of others to deliver your project.

It seems this subject comes up often.

Although, I agree that you need to do your own due dilligence, I have noticed since I started doing a lot of training recently that most people don't know where to draw that line or in many cases actually don't do any verification of the source files.

I was recently training some architects in revit talking to them about the civil source files and they were entirely lost on the concept of checking the coordinates and identifying source file innaccuracies - they were even unsure how triangulation worked. It seems logical to me but I had good mentors when I did my apprenticeship way back maybe.

So is this not something that is being taught in University/College?

Kind of off topic, maybe a question for another thread entirely, but there seems to be much contention on this topic each time.
Yes you are right in that I presume others would do the checking that I would do when I answer these questions as I assume its common practice, but it seems maybe not so common?

One point of contention: The stamped drawing from the Civil Engineer or Surveyor, is NOT the electronic file. It's not a safe assumption that the coordinates are correct just because they are responsible with delivering a survey with printed coordinates on it.

I wouldn't assume it's good, personally.

Sent from my Phablet. Please excuse typos... and bad ideas.

Aaron Maller
Director
Parallax Team, Inc.

Great, that's what forum discussions are for.

But you miss my point: you are proposing Maria do what you would do - which is not the same as suggesting Maria consider doing the things you have just listed (check contract, ask someone, verify received information, etc)

The provision of a "geolocated survey" does not, by law, in itself, hold the surveyor to any responsibility unless such is indeed stipulate by the contractual parameters of that particular project appointment - which we here, understandably, are not privy to. By your own admission, get-outs exist - but there is no get-out for assumptions - and expecting diligence in others is not the same as exercising diligence yourself.

We do agree on one thing; one should never edit/manipulate the received work of others.

Going to have to disagree there.

You are right that we don't know what the surveyor was mandated to do, but if his drawing is geolocated we can presume that he didn't do the work for free.
Also I can go ahead and look up the contract and see what he's supposed to provide. Or I can ask someone that should know (the principal engineer for example)

If I'm going to use either the survey plan or the architect plan to inherit the coordinates then I am assuming they got it right.
Of course I can go ahead and verify those coordinates myself - but to what level of accuracy, because I'm not a surveyor...so I can take a public document aerial survey for example and check the coordinates are "about right" but I'm not paid to confirm this, nor to take responsibility for it.

In all cases, if there is a survey plan, and its been geopositioned, then the surveyor takes responsibility for the accuracy of the cad file he supplies.
If he then has a clause saying "we take no responsibility for the coordinates because we werent mandated to do it" then thats another issue.

I can only talk in generalities, without knowing the minutia of every contract - I "assume" the technician will do their due dilligence and check and verify their incoming source files as much as they can but thats not always the case....Its not however up to me to CORRECT the source plan if it is wrong. And If I decide to put my coordinates different to my source, then I am the one taking responsibility for something that is outside of my mandate.

In my experience, it is best never to assume. Both could be "wrong".


Er, not always - again let's not imagine we know what the surveyor was instructed to do, and what said surveyor actually did.

There is great risk here advising someone to act based on assumptions. Hence why I earlier recommended Maria do some investigative work of her own - because everything offered here is contestably conjecture based on "just" Revit-process.

So you are linking and inheriting from 2 different sources.
It is your sources that don't match.
Revit is doing exactly as you asked it to do.
You will probably find that the architect file is incorrect. The survey file is the one you should "assume" is correct because they have been paid to put this coordinate system in place. The surveyor takes responsibility in the project for the coordinates of the project therefore always use the survey file if there is a conflict between the dwg files coordinates.

Link your survey file, acquire coordinates and then just link and align your floor plan afterwards as the coordinates are clearly not correct / in conflict with the survey plan.

You should tell the architect (or whoever it is) that their coordinates are not correct.

Theoretically as a test before you link it in revit, open the survey plan DWG and insert the floor plan as an XREF into the survey plan (dont save it) and see if the floor plan aligns as it should in the survey plan.

You always need to start looking at your SOURCE files when linking and alignments start to go bad.

No you won't, the coordinates are always in the cad file. This is confusing i know but in revit you don't usually model in real world coordinates because your building would be slightly angled and your levels would have odd numbers. So you model your building as you want it on a sheet(drawing). Then you bring in your site and move your site(real world coordinates) to match your building position(rotate it and move it as needed). Then you aquire the coordinates of the site model in your building model file and now they are "shared". Or you can create a site model(real world coordinates) and link your building model into it, move and rotate your building model to the site model and "publish" the coordinates back to your building model. Either way works. For you floor plan DWG, I would bother bringing that in at all, but if you must for an underlay just bring it in and move it where you want it. Then test an export, when you export, export a view set to "true north" and see if it exports your plan in the right place in cad. The final option is to use the specify coordinates at a point. Same process as above, just don't aquire the coordinates but use the specify tool and pick a location that you know in cad and enter those values in revit. All of those options should work.