Create toposurface from CAD file- Elevation

[mairh_tsek]

Hello all,

I have a .dwg file with the cadastral plan in elevation zero and also some points in an elevation around +800.0m,  from which I want to create the toposurface in Revit.

When I import the .dwg file in Revit and create the toposurface, I have a distance of (800m) between the building and the toposurface.

If I move the toposurface down, the points lose the absolute elevation value that they have (after is quite difficult to calculate the slopes that I need etc.)

Which is the workflow that I need to do in order to avoid this problem?

I want when I import the .dwg file in Revit to be in the elevation of my building in order to create the toposurface in the same place with it.

What you will do in my situation?

Thank you in advance!

[loboarch]

This might help a little.

http://help.autodesk.com/view/RVT/2019/ENU/?guid=GUID-6A655821-3E03-4452-99A8-E74BFF677B06

[Sahay_R]

@mairh_tsek the geolocated information from the terrain is what you need. Link the building model into the toposurface and manipulate it as you need.

[mairh_tsek]

@loboarch,

If I relocate the project the distance between the building and the toposurface remains.

How you manage to create the toposurface in the level that you have the building?

Or you also always move the toposurface in the desire level?

Thank you!

[mairh_tsek]

@Sahay_R ,

Is it not possible to have the toposurface and the building on the same file? As when I want to create a Pad I should link the building to the topography file.

[loboarch]

---

@mairh_tsek wrote:

@loboarch,

If I relocate the project the distance between the building and the toposurface remains.

How you manage to create the toposurface in the level that you have the building?

Or you also always move the toposurface in the desire level?

Thank you!

---

In the video the already down at "0" already moved down there or created there to begin with. In the video the relocate project tool is used to establish sea level annotation values.

[Sahay_R]

Yes, you can have both in the same file - but then moving the building around will be very very painful. This way positioning the building correctly will be easier. Link the building into the toposurface, and then create building pads.

[mairh_tsek]

@Sahay_R,

So Will I need to have a file with the building only and a second file with the toposurface, the pads, the site components (and all the things that are related with the toposurface) ? 

Which is the workflow in order to move the building and to save the new position?

If we have to make a change to the building location, I will link the building into topography ( by shared coordinates), I will move the link building (Move command)  and in order to save the new location of the building I need to go Manage> Coordinates > Publish Coordinates? 

Thank you!

[barthbradley]

Sounds like you want to Acquire Coordinates from the CAD Import. Move the CAD Import to the correct elevation RELATIVE TO YOUR BUILDING, and Acquire it's Coordinates.  DO NOT MOVE YOUR BUILDING TO MEET THE CAD ELEVATION.  

...if you've already created your Toposurface from the CAD, then move the CAD with the Toposurface. 

[mairh_tsek]

@barthbradley, 

Yes, If i move the cad down in order to be in the same level with my building and acquire coordinates. The values of   each point of the toposurface will not be correct. (For example a value 800 will be -10 )

I dont know how I can  explain it better.

[barthbradley]

Are you talking about the points that you see inside sketch mode when you edit the Toposurface? If so, don't worry about those point elevations.  Those points are internal data only. 

If an absolute point elevation inside Topsurface sketch mode is +800 feet, and you close out of sketch mode and  move the Toposurface down 810 feet -- that same point will now be -10 feet.  It is relative to the Project's Internal Origin -- not any real world elevations.   

Now, I'm not clear what method you used to relocate your Survey Point, but the Survey Point should also at the base of the Toposurface.  When you go to place Spot Elevations on the Toposurface, use a Spot Elevation with its "Elevation Base" parameter set to "Survey Point".  So, when you place a Spot Elevation on the Toposurface, it will report the "real world" elevation at the location it is placed. 

Does that clear up any confusion, or did I make it worse?    

[mairh_tsek]

@barthbradley , 

Thank you for your time!

Yes I meant  these points!

So one more try to understand if the workflow that I do is correct or not..

The revit building is in 0.0 and the .dwg georeference file that I link in Revit have the points in 

+800.

So in Revit I have the building in 0.0 and the points of the .dwg 800m upper.

I move the .dwg file down 800m and I create the toposurface, after I go to the Project base point-clip it-and give an elevation 800.0m.

The internal point of the toposurface show others value as you said, but yes I can use the spot elevation tag with an elevation origin of the survey point in order to have the absolute value each time.

The problem is when I make the calculation in order to create the slope for the pads etc. each time I need to discount 800m from my calculations in order to create the pads to the 'correct elevation'.

I had the same problem to an previous  project. Is there not any way, to have the points of the .dwg file directly to my building? 

Do you always move the toposurface up or down in order to match your building and after you relocate the project respectivly?

Well..sorry for the long text... I am confused about this issue.

Thank you!`

[barthbradley]

---

@mairh_tsek wrote:

I move the .dwg file down 800m and I create the toposurface, after I go to the Project base point-clip it-and give an elevation 800.0m.

---

You DO NOT move the Project Base Point.  YOU MOVE THE SURVEY POINT WITH THE CAD/TOPOSURFACE. 

Follow these step precisely:

1. Delete your CAD and Toposurface from the Project.

2. Go to Elevation View and turn on the Project Base Point and Survey Point.

3. Select the Project Base Point, Unclip it and select "Move to Startup Location". Now Clip it.  

4. Move your CLIPPED Survey Point to the Project Base Point. The PBP and SP should now be in the EXACT same location.

5. Place a LEVEL running through the PBP/SP location. Name the Level "Sea Level".  

6. Go to 3D View and Import your CAD back into the Project -- CENTER TO CENTER.

7. Go to the Site Plan View and move the CAD into the correct "x,y" position relative to your Building. 

8. Go back to 3d View and select Toposurface on the Massing & Site and then select "Create From Import" => "Select Import Instance".   Now pick the CAD.  Click on Finish Surface to exit out of Toposurface Sketch Mode.  You should now have a Toposurface overlaying your CAD.  

9. Go to Elevation View and turn on  Topography, Survey Point, Levels -- and CAD.  Turn off the Project Base Point.

10. Select the Toposurface, Survey Point, "Sea Level" and CAD, and move them all down 800 feet (or whatever distance it needs to be moved so that the Toposurface is at the correct "z" position relative to the Building).  

11. Optional: Pull a dimension between the "Sea Level" and "Level 1" and LOCK IT.

12. Optional: Pin the Survey Point. 

Now, any Spot Elevations you place on the Toposurface should have their Elevation Base parameter set to either Survey Point  -- or to Relative.  When using a Relative Spot Elevation, you need to designate "Sea Level" as the Relative Base.    

Regarding the issue you are having with Building Pads; I am unclear how this relates to the Toposurface. Though Building Pads host to Toposurfaces, they are relative to Levels -- not Toposurfaces.