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Thread: Toposurface is above my roof!!!

  1.    #11
    Member Barth's Avatar
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    Quote Originally Posted by billiam View Post
    you've been using Revit for over 30 years???
    You misread.
    Last edited by Barth; August 10th, 2017 at 07:34 PM.

  2.    #12
    Member Barth's Avatar
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    Quote Originally Posted by billiam View Post
    What I'm wondering is if we all model topography in the same way...
    We don't all model topography in the same way (e.g. use the same workflow).

  3.    #13
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    Barth, I'm not trying to be caustic, but your workflow is contrary to every workflow I have ever seen in best practice methods.

    We go to the mountain, we don't bring the mountain to us.

    In majority of cases, the file provided by the surveyor (if the surveyor is any good) will be at absolute level.
    Also, as mentioned by Ian, there is also a project level of 0 at ground level.

    In most cases we see something like this 0 = +412.75 m

    I absolutely can move my topography down to be at my project zero.
    But this limits me to using project base point spot élévations.
    What I have seen in my experience (I also have significant industry experience)
    is that slabs and réservations in walls (pénétrations) are given an elevation using the project base point to be easy for the builder to understand.
    And any spot élévations on parking, or exterior "civil works" are given absolute elevation values.

    Assuming this is the case for the OP - as it has been what I have seen as standard in the industry for over 20 years, then I would recommend setting the elevation of the ground floor to the actual absolute value of the project (example +412.75m)

    This allows you the flexibility of being able to report the actual values and your project values.
    In addition, as we "virtually" constructing the building personally I prefer to be actually correct than just modeled at a theoretical and arbitrary 0.

    Graphically - either option will work.
    Only one of them is actually the correct way to report your spot elevation values.

  4.    #14
    Senior Member willsud's Avatar
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    As a small aside, I see mention of letting Revit mesh the toposurface from the contours

    I discovered a few years ago that my land surveyor could triangulate his survey points as 3D faces which are then on a DWG layer in the 'drawing' and picking that when creating the toposurface in Revit gives more accuracy to the toposurface.

    Although the work of minutes he didn't do this routinely as he said that no-one ever asked him apart from me

  5.    #15
    Member Barth's Avatar
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    Quote Originally Posted by Karalon10 View Post
    Barth, I'm not trying to be caustic, but your workflow is contrary to every workflow I have ever seen in best practice methods.
    Karalon10, I'm not trying to be caustic either, but your workflow is equally contrary to every BIM / Coordination workflow I know. However, since you mention your “significant” experience, I’ll conclude that we either work in a different part of the world (or universe), or you just plainly misunderstood me.

    First of all – I don’t understand your “mountain” metaphor. The workflow we use doesn’t involve any “mountain moving” at all – just LINKING and COORDINATION.

    We don’t mix metaphors. By “metaphors”, I mean “disciplines”. (C’mon, Karalon10; admit it: that was a pretty good one. Made you chuckle, didn’t it?)

    Second of all – and as is always the case on these forums – we are all reading arcticnyc’s post differently. There are no bad answers here – just different approaches, and opinions, based on how we have interpreted the author’s situation.

    Third and lastly – Arcticnyc states that his “project is ready”. From this statement, I am concluding that it is fully completed with datums, annotations, views, sheets, etc., etc., etc. I would never ever advocate that someone move all his work at this point. That’s a potential nightmare, at best. Frankly, I don’t see how any “experienced” Revit user could even entertain that option. So, understandably, I’m pushing back hard on that one. Been there, done that – won’t do it again.

    Karalon10, you make some good points. I get where you are coming from. But, I’m going to have to respectfully disagree with your major assertion. It’s professional; not personal, you understand.

    There are several workflows that could be used to “properly” place the Topo in the same environment as the Architectural Model. This topic has been discussed and debated ad nauseam over the years – in every forum. I would encourage Arcticnyc to start reading and practicing with those various approaches, outside of his current project, until he finds the ones that works for him – in his current project, as well as his future projects.

    I wish you well, Karalon, and look forward to reading you again.

  6.    #16
    Member Barth's Avatar
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    Interesting puzzler; Topo Surface origin points are at 0’-0” (in sketch mode), but the Topo Surface is 200’-0” above project’s 0’-0” Level / Project Base Point elevation. Hmm? Still think moving the project UP is the way to go here? How would you go about that? It’s a sincere question. See attached.
    Attached Files Attached Files
    Last edited by Barth; August 12th, 2017 at 09:41 PM.

  7.    #17
    Forum Co-Founder Twiceroadsfool's Avatar
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    Wow. So much mis-information in one thread, all in the name of trying to one-up one another and prove each other wrong. Lets clear that all up with some facts:

    1. Topo in Revit is always modeled RELATIVE to the level it is hosted by. Topo is in NO way *always absolute.* No other way to say it, other than the statement is flat out wrong. If you have LEVEL 1, the entire TOPO SURFACE has an offset from the level. If you use the offset from the level, and type in 100 feet, than the topo sits up at 100 feet. THEN, when you edit the points on the topo, the points will read ZERO (which represents the offset from the Topo original level which is now 100 feet above Level 1). The POINTS elevation and the overall TOPO elevation are DIFFERENT.

    2. BECAUSE of issue number 1, some people CHOOSE to have a level at *absolute 0" which they call "Site host" or something similar. Now, this all depends on how you choose to set up your Levels and your coordinates in Revit. THAT part, has several nuances to it, and each nuance has different "opinions" on what is right or wrong.

    3. You DONT necessarily HAVE to ever MOVE the TOPO up or down, to get it to read correctly. You also DONT necessarily HAVE to ever MOVE the model, up or down. It all depends on how your coordinates are set up, AND there are more than one coordinate system to use. This gets even more complicated because you can also handle *Site* in a different file, and not worry about it in your project at all.

    My personal philosophy on all things coordinates and all things sites:

    A. I dont EVER touch Project Base or the Relative Origin. They both stay RIGHT where they are originally.
    B. I dont EVER move my levels up and down. EVER. I dont EVER move my Building Model up or down, either.
    C. Shared Coordinates can have multiple coordinate systems, meaning you can show 0', or 100', or actual elevation, once youve set up coordinates and elevations correctly.
    D. Once my coordinates are set up correctly, i DO manually move the TOPO surface at a known elevation location, so it is correct in the model. I then place a level down at "actual 0" and make the topo off of that Level. That way when i edit my points, i am typing in actual elevations from the Civil engineers. I do this even if my Site is in a different model.
    E. I always set up True North prior to Coordinates. Its true that you dont HAVE to, but it makes things simpler. I do this the same way i do my coordinates. MANUALLY Link in the CAD, move and orient it to align with Project North, then manually set Rotate True North to orient the file the way the CAD file was.

    It is true, that in a previous life (working in AutoCAD) we linked in "defining data" such as civil, then oriented ourselves to it, and started drawing. Its also true that in Revit, it works backwards. We dont move the dishes on the tablecloth, we move the tablecloth underneath the dishes, and then we use Shared Coordinates to change the coordinate values.

    There is some "manual data coordination" in ANY of the ways you work with Civil in Revit. If you think linking in the CAD file, using the import to make your topo, and "moving your model around" is saving you from manual work coordinating, thats a false sense of security. My way has manual coordination, and the other way has manual coordination.
    willsud likes this.

  8.    #18
    Member Barth's Avatar
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    Thank you Aaron. Well said.

    I’d just like to add one more thing for @arcticnyc’s benefit, since this is his thread:

    Arcticnyc: Your Topo Surface’s internal points are most likely relative to your project’s Origin. You can verify this by selecting the PBP, unclipping it, and then right-clicking on it and selecting “Move to Startup Location”. The PBP will reposition itself at your project’s “WCS” zero origin (if you’ll pardon the AutoCAD term), which is where the base of your Topo Surface is likely originating from. This best explains what’s going on in your project, based on your description. Hope this helps you. Good luck.


  9.    #19
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    Moving your topo surface AWAY FROM ABSOLUTE VALUE is moving the mountain. You are making the mountain, come to you.
    If you adjust the ELEVATION value, there is absolutely no change to any of your documentation, at all. Period.

    I can see you've decided to go with the personal attacks rather than have an adult conversation so I will leave it there.

    If it was Professional, and not personal, you wouldnt have gone with the snide remarks such as "work in a different part of the world (or universe)"

    I'm only here to help other people with my own personal experience, not have dick measuring contests.

  10.    #20
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    Just for the record, I never once said move the model, I said change the coordinates using the manage tab.

    "Topo is in NO way *always absolute.* "
    This was based on a conditional which I clearly stated

    "In majority of cases, the file provided by the surveyor (if the surveyor is any good) will be at absolute level."
    This also places a lot of trust in your surveyor file, and of course, you should verify and coordinate this.

    In addition the OP clearly stated this
    "toposurface that has absolute elevation of all points = 0'-0' is 200 feet above my building "
    Which led me to believe he had simply imported a cad file and made a topo surface from it which led me to believe his topo was correct and his project was modelled at 0 with no changes to his coordinate system.

    It also depends entirely how you've modeled your topo surface.
    If you have a decent surveyor who has provided you with a Civil3D surface, you are simply clicking on a linked cad file and making a topo surface from his link (which will be at ABSOLUTE level)
    If you are going to a level in plan, creating a topo surface by making your own points, then the workflow is different.

    basically anything I said was "conditional" based on certain assumptions - such as the project elevations likely being not set up.
    In addition, I can adjust the project elevation without any "consequences" on my documentation, ASSUMING my spot élévations are reading project base point, and not relative.... and if not then its a pretty simple fix.

    Unfortunately I don't have the OPs file open so ....
    quite frankly the method described by twiceroads is what I was describing but perhaps not well communicated.

    Of course I need to verify and coordinate that my levels are correct for both topo and project, I would hope that goes without saying.
    Last edited by Karalon10; August 14th, 2017 at 09:37 AM.

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