Here's the scenario. You have a topographic survey completed in CAD by the surveyor. Its a good file and you are able to import the CAD file and create Revit topography from the survey. Nice!
Now, you want to model your building. When you enter one of your elevation views you realize the topographic map is at 29'-0" and your Level 1 is at 0'-0". Hmmm.... You want to model your building at the correct elevation (29'-0") but you want your wall sections, elevations, and details to read 0'-0" on your documents. Keep reading to find out how you can control what your Levels will show...
Thankfully, Revit gives us an option to control two different origins (for lack of a better word). The two origins are:
Project Base Point:
Survey Point:
You have probably come across these two points and not even realized it. In fact, the default template has them overlapping in your site plan:
I will restate the Autodesk Help page for a quick explanation on each point (because it is written very well):
Every project has a project base point 
and a survey point 
, although they might not be visible in all views, because of visibility settings and view clippings. They cannot be deleted.
The project base point defines the origin (0,0,0) of the project coordinate system. It also can be used to position the building on the site and for locating the design elements of a building during construction. Spot coordinates and spot elevations that reference the project coordinate system are displayed relative to this point.
The survey point represents a known point in the physical world, such as a geodetic survey marker. The survey point is used to correctly orient the building geometry in another coordinate system, such as the coordinate system used in a civil engineering application." (Autodesk Help, 2014)
Following this definition and the example above what do you believe should be the Project Base Point and Survey Point? Well, we want the project base point to be 0'-0" at 29'-0" "physical world" elevation.
I typically approach this problem by leaving the Survey Point where it is (our real "physical" world origin) and moving the Project Base point up to the finished floor elevation (29'-0" in our example).
To move the point simply enter an elevation or section view, hit the light bulb to toggle hidden elements and you will see the two points. Tab select the project base point and use the move command.
In the image above you can see the survey point on the bottom and the project base point even with Level 1. Note that the Level 1 states 0'-0" yet it is at an absolute elevation of 29'-0" thanks to the Survey Point. How can you double check this?
Following this definition and the example above what do you believe should be the Project Base Point and Survey Point? Well, we want the project base point to be 0'-0" at 29'-0" "physical world" elevation.
Example 1: New Project
I typically approach this problem by leaving the Survey Point where it is (our real "physical" world origin) and moving the Project Base point up to the finished floor elevation (29'-0" in our example).
To move the point simply enter an elevation or section view, hit the light bulb to toggle hidden elements and you will see the two points. Tab select the project base point and use the move command.
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| Click image to enlarge. |
Simply click the level in a section or elevation view, click "Edit Type", click "Duplicate" and rename your Level family to include "Survey" somewhere in it. Now, where is says "Elevation Base Point" change it to "Survey Point".
Now, when you click Okay you will notice the level will dsiplay the elevation based on the survey point (29'-0"):
I mention that this example is for new projects because when you move the project base point of an existing project it opens up the possibility of ruining many views, sheets, sections, details, etc... It may work but it is a chance I am not willing to take.
Example 2: Existing Project
So what do you do if you are in an existing project and the project base point and survey point have both been moved to 29'-0" or at 0'-0" and you want it at 29'-0"? Simple, instead of moving the Project Point up you can move the survey point down. The nice thing about moving a survey point is no views will be ruined (the project stays in place).
BIM After Dark - Volume 2: Production
If you liked this tutorial you will definitely like Volume 2 of the BIM After Dark series. Volume 2 demystifies the construction documentation process. The full length videos show you how to create a set of construction documents with Revit faster than ever before. In addition, it is packed full of sample files, templates, and goodies.
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Rukiye · 514 weeks ago
I really find your blog and posts useful and constructive. I have a thing on my mind about this post. What i am wondering is would it be the same if I did it with "relocate project" command. It changes the levels to the survey point height as well. But, would there be any difference on the conclusion? Does that ruin anything of an existing project?
Thanks
TheRevitKid 72p · 514 weeks ago
Ryan T · 514 weeks ago
TheRevitKid 72p · 514 weeks ago
Dave · 514 weeks ago
Thank you!
Shane · 514 weeks ago
Michael D · 514 weeks ago
Moving the project base point is indeed the same as using "Relocate Project" (my preferred method since views are not affected and you only need to move one thing - not levels and base point). The difference comes when you unclip and move the project base point then re-clip it:
If, in elevation, you:
- Manage -> Position -> Relocate Project OR Move the clipped Project Base Point and levels (shared height will now read whatever you set it at with project base reading zero)
- Site Plan -> Toposurface
- Start placing points - options bar set to "absolute elevation"
- Any heights you enter are RELATIVE TO THE ASSOCIATED LEVEL
If, in elevation, you:
- Move the levels up to the new shared height
- Unclip the Project Base Point and move it up (then re-clip it) (shared height will now read whatever you set it at with project base reading zero)
- Site Plan -> Toposurface
- Start placing points - options bar set to "absolute elevation"
- Any heights you enter are RELATIVE TO SHARED ZERO (or survey point if it started in the same place as the project point).
Seaner · 513 weeks ago
Having geodetic elevations proves useless in the toposurface when this happens, especially if you have set up your PBP and SP like you have shown above.
I hope this fix is forthcoming...but is there a technique you have come across to address the toposurface points referring to some magic invisible point?
TheRevitKid 72p · 513 weeks ago
@pix3lot · 504 weeks ago
What I tell users is that the Elevation Base parameter has a naming issue and that it doesn't really mean the Survey Point object, but rather it means Revit's Internal, static 0,0,0. So if you want levels or datum elements to read different elevations one must move the PBP and not the survey point.
@pix3lot · 504 weeks ago
My general recommendation would probably be to leave the Survey Point at the internal 0,0,0, or only move it in a clipped state to keep the elevation of the survey point in sync with the datum elements.
@pix3lot · 504 weeks ago
TheRevitKid 72p · 504 weeks ago
Denise · 455 weeks ago
I found this post which was very helpful but I am still having some issues.
I created my topography and initially changed the real height numbers but then regretted it and returned to the original topography heights (100.25 mt) and wanted to move my model to that height as well and leave that as my level 0. I changed the elevation line to survey point just like you say but my model is still underneath my topography. Also the survey point itself when i turn on the hidden objects it is underneath the project base point and the topography (set at 110.25 mts) What am I doing wrong? Please help.
Michael · 421 weeks ago
Carlos · 311 weeks ago
Carlos · 311 weeks ago