Forums >> Revit Building >> Technical Support >> Toposurface and datum

mongopac

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Created a project, designed building, THEN got survey.  Not a problem.  I relocated the project so that now project 0.00 is actually at Survey Point 40.83.

Here's the problem.  I created a Datum plan, which is set at 0.00.

I create a new Topo, set the elevation to 40.83, pop down the four corners, and bingo, I get a topo at 81.66, 40.83 above where it should be.  Click on Edit Surface and pick a point, it reports 40.83 even though I can look at it in section and see it way up there at 81.66.

What is going on here?

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Pavan

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Joined: Sat, Mar 19, 2005
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After Relocating your project...draw an extra Level(40.83m below your present 0 level) which is at -40.83 meters.

Now import your survey dwg at this new level using 'Origin to Origin' and create new topo.

-----------------------------------

Pavan Reddy

Revit Manager

Intelligence is not always knowing the answers, it's always asking the questions.

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mongopac

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Tried it, but no luck.  Same problem.

I don't quite know why an imported dwg would affect the creation of a topo in the first place.  FTR, the imported dwg DID end up on the new datum level, but the topo still generates itself, apparently, based on the original ZERO datum in which the project was created.  I even messed with the original level 0, thinking the topo was somehow attached to that, but that didn't help either.

Given that this problem existing in version 2009, I'm guessing that Autodesk just hasn't fixed it.  I'm going to put it to them and will let you know if they respond.

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teafoe5

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Did you relocate the project base point and the survey point?

http://wikihelp.autodesk.com/Revit_LT/enu/2013/Help/0075-Revit_LT75/0179-Prelimin179/0214-Project_214/0220-Project_220/0222-Moving_P222

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mongopac

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I don't quite know what you are asking.

Currently, Survey point is N/S = 0.00, E/W = 0.00 and Elev. = 0.00

Project point is N/S 2106, E/W = 2025+ and Elev is 40'-9 and change, which reflects the station point offsets noted on the survey. 

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mongopac

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Here is the outcome of my inquiry to Autodesk.

To review, what I am essentially asking Revit to do is to be able to have a toposurface report the various topo points as survey point, and not project points while either creating it or in edit mode. 

In that way, I can edit a point off of a revised grading plan, for instance, by inputing real survey points received from the Civil, without having to manually translate them into project points.

Revit can't do that. Toposurfaces only report project points.

So, it goes to the wishlist.

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WWHub

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Why edit the topo, why not just create a new one from the points file?

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mongopac

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I could, and frankly, I didn't think about it, but there are some downsides unless you can tell me something new and exciting I don't know.

1.  If I simply generate a new topo, I can't get Revit to report cut and fill quantities between existing and revised.  I would have to manually add it to the plans, no?

2.  The topo from the civil reports top of conc., top of curb, etc, which, strictly speaking ain't the dirt, so when I import the topo, the sidewalk elements I create, for instance, are at the same elevation as the dirt.  Typically I will go back though the T/C points of the imported topo points and subtract 4" for the thickness of slab in those areas so that it looks correct in section. 

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mongopac

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Got a final response from Autodesk about this.

The key, apparently, is that you cannot make a toposurface first and THEN relocate the project and ask it to report survey points.  The project must be moved first.

http://wikihelp.autodesk.com/Revit/enu/Community/Tips_and_Tricks/Modeling/Create_a_Toposurface_Using_Sea_Level_Elevations

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Pavan

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I feel I gave the right solution because that worked for me.

-----------------------------------

Pavan Reddy

Revit Manager

Intelligence is not always knowing the answers, it's always asking the questions.

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