Survey elevation (relative to sea level) and project elevation

[chughes]

How can I create a toposurface whose elevation points are relative to sea level and not relative to the project elevation?

I have moved my project elevation to where top of slab = elevation above sea level.  I leave my survey elevation at 0'-0" (sea level).  I now want to draw a toposurface based on a survey with elevations relative to sea level.  However, when I draw my toposurface and input my point elevations, the point elevations are relative to the project elevation, not the survey elevation of 0'-0".

For example:

Project elevation = 15'-0"

Survey elevation = 0'-0"

Toposurface point elevation = 14'-0" (I would think this would put my grade 12" below my top of slab)

My toposurface is 14'-0" above my project elevation (top of slab) and 29'-0" above the survey elevation (sea level).

See below for reference.

What am I doing wrong?

Thanks.

[chughes]

No solution other than math to subtract from the project base point or an exterior topofile that links in...

[chughes]

I haven't found a way to do this, but I have been accused of having abnormal skull density in the past.

I have two numbers that exist in any project.

My survey point, from which I create and lay out my site elements, including topography (North Atlantic Vertical Datum (NAVD)).

My base point, from which I lay out my building elements, including elevations of my levels (Level 1 = top of slab(0'-0" ARCHitectural)).

Since both of these points exist in Revit, it seems doable, but I only have the option in Revit to set my topo at Absolute Elevation and Absolute Elevation is in reference to Level 1 - 0'-0".  In order to set my topo elevation points, I have to math up the delta between Level 1 - 0'-0" and where I want my topo to be (or is) relative to Level 1 - 0'-0".

Ideally, I would be able to keep my project base point at Level 1 - 0'-0" ARCH and my survey point at 0'-0" NAVD and tell Revit that my 0'-0" ARCH is 17'-0" NAVD (for example), set my topo points at 16'-0" (based on the survey) and have my Level 1 top of slab 1'-0" above my grade *and* at 0'-0" ARCH.

The only way I have seen to accomplish this is a separate topo model, linked into the building model, and moved vertically -16'-0".  I don’t *want* to do this, but I have not seen another alternative.  I would love to know if it is there is one.

[jfrazierdorsky]

I have given up using Site Designer, it doesn't give me the ability to set the dimensions easily without doing math for every freaking point. Yes you could build another model but that is a pain. Instead of using site designer for topo points I just use floors. I have set an elevation point at zero NAVD or NGVD. Luckily I am in Florida so most of our elevations are like only a few feet above zero. I set that floor to zero and then raise points to whatever the survey says then adjust from there to my building. I was hoping to use site designer for the curb and gutter tool, but it doesn't work very well either. So I have to make curbs and gutters as floors too. There is no 3D model ability to set the height of a curving object, at least not that I have found. It would be nice to create a curb/gutter using a generic model sweep, but you can only do flat versions and not add topo to it.
So I have given up. Going to stick with my floors for site elements and forget site designer. For as cool as it looks it is not very friendly to Architects.

[lecartuchen]

Better later than ever...

Hope this helps.

https://www.youtube.com/watch?v=dAfdI2B00pY 

[chughes]

thanks @lecartuchen 

This is one piece of the puzzle and is helpful.  I have used this to create 2 different level heads so I can show NAVD and ARCH elevations in the same project. 

The original question is still unresolved, which is how do I set my topo points to reference Survey Base Point instead of Project Base Point.  When drawing the toposurface the only option I have to set elevation is 'Absolute Elevation'.

Absolute is tied to the Project Base Point.  The presence of the dropdown gives me hope that there are future plans for other reference point (Survey Base Point) options, otherwise why even have the dropdown.  Autodesk just needs to hurry up and implement it.

[ankere]

The name of the game is "Fix your coordinates Revit Team". Management of site and building to create a complex topography is overly painful and very very counter intuitive. I'm waiting for update on the issue. At least you can add an option to use survey point as topo coordinates.

[Anonymous]

Can't believe this is actually an issue with Revit. I thought for certain I was doing something wrong, but in the end glad to see modeling topography by actual surveyed elevations in relation to project base point and survey point is not possible within the same model. I can't imagine the issues that may come from moving the topo up and down every time you want to make changes based on actual sea level survey elevations. Opting to proceed by linking separate model... good grief.