Topography Elevations Not Matching CAD Levels

[Anonymous]

Hi,

I have a topographical surface which was generated from points from a CAD file. The surface looks somewhat accurate and seems to follow the points as Revit is programmed to do so. The issue is that when I click to edit the surface the Elevation levels of the points seem to be completely different from that of the markings on the CAD drawing.

Does anyone know why this is and how I can correct this? Any help would be much appreciated :).

[barthbradley]

Move the CAD up or down. That's how it's done.  Keep in mind that the Point Elevations inside Toposurface sketch mode are relative to the Internal Origin of the Project.  If you have a known Point Elevation on your CAD that should read 100 ft., but instead it is reading 0 ft. in Toposurface Sketch mode, then lower your CAD in the Project 100 ft.  Make sense? 

BTW: those internal Point Elevations really don't matter. What matters is what the Spot Elevation reads when placed on the spot. Spot Elevations are not relative to the Toposurface. They are relative to the Survey Point or Project Base Point  or relative to a defined LEVEL.  (e.g. the Spot Annotation's "Elevation Origin").  

....lower your CAD 1349.463.  Now that point will "read" correctly inside Toposurface sketch mode.  

[Anonymous]

Hi Brad,

Here are the results after lowering CAD in which they appear to be the same:

(Please note the 100 difference is because I moved the topo down 100, reversing this the results would be the same). The point I have highlighted is one that makes up the topo and is not part of the CAD. Maybe this was not clear in my first post. 

My spot elevations are reading okay:

I just want the elevations of my topo points to match that of the spot elevations and CAD as I need to make minor adjustments to the points based on calculations made from the CAD sea level points.

[barthbradley]

You misread what I wrote, @Anonymous. Let’s try again.

IF the Spot Elevation shown in your bottom screenshot is correct – AND you want the Toposurface Point shown in your top screenshot to read the exact same Elevation – AND they are the SAME units – then go to Elevation View, select the Toposurface AND the Spot Elevation’s “Elevation Origin” (e.g. Project Base Point, Survey Point or Relative Level) – and MOVE the both of them UP 38447.8.

All that being said, If you really have to keep the Toposurface Points relative to the Revit Project’s Hidden Internal Origin, you should place your Project Base Point at its Startup Location, insert the AutoCAD dwg Origin-to-Origin, “Create from Import” the Toposurface, and pin both the Toposurface and AutoCAD dwg.  Then I would suggest placing another Level at the Startup Location, naming it “Sea Level”, and pinning it.  When placing Spot Elevations on the Toposurface, use a Spot Elevation TYPE that has its Elevation Origin set to RELATIVE.  On placement of these Relative Spot Elevations, set their Elevation Base on the Options Bar to “Sea Level”.