Topo levels issue

[ianrhale]

Hi all. I've read lots of posts relating to my problem, all with similar issues - i must be missing something because i cannot solve it after hours of trying. I am fairly new to topo surfaces.

I have the survey and project base set at 0.00. When i model a topo surface and input levels 'correctly', they are all off by +1938mm and I cannot see why. In the surface edit field i am inputting correctly, but they are off when it generates. I put a dummy 'floor' in at the correct level to gauge the difference. Where do i start to look to trouble shoot?

[ianrhale]

[barthbradley]

Toposurface's point elevations (e.g. those point elevations shown within edit mode) are relative to the Internal Origin of the Project. Contour Labels' and Spot Elevations' Elevations are relative to the "Elevation Base" (e.g. Survey Point ORIGIN, Project Base Point, Relative) that the annotation Type is using.    

https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/Displaying-only-wa...

[ianrhale]

Thanks, i did think that - but i thought the internal origin was always at 0.00, and if my survey and base points are at 0.00 then should the levels then not all match?

(link was to a wall core page so i couldnt check it there!)

[barthbradley]

Sounds to me like you just need to go to Elevation View and move the Topo up/down to correct the Elevations being reported.  

[barthbradley]

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@ianrhale wrote:

Thanks, i did think that - but i thought the internal origin was always at 0.00, and if my survey and base points are at 0.00 then should the levels then not all match?

(link was to a wall core page so i couldnt check it there!)

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Levels? Sorry, I though we were talking about spot elevations on the topo.  I don't understand where Levels come into play here.  

...If you have a level ground plane on the topo and that level ground plane is to be aligned to a particular Project  Level, then move the topo in Elevation View to a align that ground plane to the appropriate Project Level.  

[ianrhale]

Yes sorry, I am confusing things with my terminology.

By levels i mean spot levels/spot elevations, not Revit levels. The Revit levels are fine, the other spot level/elevations are fine (ie the top/bottom of the walls etc), but the survey is off.

I can make it, then move it down, and the spot elevations are then correct (and i very much appreciate the suggestion). But why is it out in the first place is what i'm trying to figure out?

[barthbradley · Accepted solution]

Moving the Topo up/down in Elevation is the  correct way to do it.  Keep in mind that you're establishing relationships between elements within your BIM Project space.  The Topo is an element just like a chair or wall or floor.  

[barthbradley]

one more point: the survey origin of Topography is generally Sea Level.  If you want to report Elevations from Sea Level, then you need to have a Level placed at Sea Level in your Model.  In lieu of a Level, you could use place the Survey Point Origin at "Sea Level" - relative to the BIM Model of course - and use Spot Elevations that use Survey Point for the Elevation Base.  

[ianrhale]

Right - thanks for all the tips. I will play around with it!