Topo contour lines not showing correct elevation

[gtdraftdesign]

I need help understanding why the revit contour lines are reading a different elevation than the CAD topo file I inserted.

I set up the Survey point elevation so that it sits at sea level 0,0. Then, I set the Project Base Point so that the finish floor on 1st level would sit at 6533'. I inserted the CAD topo and used Massing & Site to create the Revit 3D topo. However, when editing the 3D map, I noticed that the Revit contour lines are reading different elevation numbers than the CAD topo. It's really messing with my head. I'll attach images in hopes that it helps explain what I'm getting at.

Image 1 shows the contour lines at 6530' and 6532'. But, when I edit the surface of the 3D image and click on the interior points of the elevations, I'm getting different numbers. Instead of 6530' Revit is telling me that elevation is 6509' and 6532' is reading at 6511'. Is this normal? The 3D map appears to be at the correct elevation when viewing the home on the 3D map. 

I'll gladly provide more information if needed.

[barthbradley]

understand that the points elevations (the one's in sketch mode) are relative to the Internal Origin of the Project. The Internal Origin can be found by right-clicking on the Project Base Point and selecting "Move to Startup Location".  

Also, be aware that the Contour Labels are relative to an "Elevation Base", as shown in this screenshot:

CLEB.png

So, to correct yours, you would go to an Elevation View and move the elevation of the Topo 21 ft., or move the Level  that is the Contour Label's "Elevation Base"  21 ft.  Moving the Topo would be best.  

[gtdraftdesign]

I moved the Project Base Point back to its "startup location". The Elevation reads 21'-0". Why is that? Should it read 0'-0"? If I move the topo (in elevation) up or down 21' then it will be off. The points elevations would read correctly, but the map will be way off. 

[barthbradley]

I would recommend this workflow:

1. Place a Level at the Internal Origin and name it "Sea Level". Again; the Internal Origin is where the Project Base Point's Startup Location is located. 

2. Import CAD

3. Create Toposurface from Import 

4. Go to an Elevation View and lower both the Topo and "Sea Level" Level together.    

5. Pull a dimension between "Sea" Level and "Level 1" and lock it.  

6. Set your Contour Label's Base Elevation to "Relative" and set the "Relative Base" to "Sea Level" upon placement of Contour Labels

...based on what you wrote, you would lower the Topo and "Sea Level" 6533 ft. in step #4.  

[barthbradley]

I get what you did. You moved the PBP to it's Startup Location expecting it to change the Topo readings. Move the PBP to its  "Startup Location", only places the PBP marker at the Internal Origin. Nothing more.  It doesn't do anything to the Topo.  It just shows where the Zero origin is for the Toposurface's Points that are inside sketch mode.  Those internal points have no bearing on Annotations, such as Contour Labels and Spot Elevations.  Those Anno's reference an elevation from a LEVEL (a.k.a. "Elevation Base).  If you follow the workflow I listed above, the Boundary Points inside sketch mode of the Toposurface will read -6533 ft. (that's minus 6533) when you are done.  But, your Contour Labels will read 0 ft. at the Boundary.  Get it? 

[gtdraftdesign]

I started to follow along with your instructions when I realized that I imported the elevation labels along with the contour lines from the CAD file. I think what I'm experiencing is that the Internal Origin of the project is off. I can apply your instructions and make the elevation labels show the correct elevation. However, the points elevations will still read incorrectly. Is there a way to set the Internal Origin for the Project Base Point to read 0'-0"? Or is 21' the internal origin? That doesn't seem correct. This may be a moot point, but, the architect will most certainly want to see the elevations in sketch mode. I just want the labels from CAD to match the points elevation numbers

[barthbradley]

The Internal Origin is FIXED at 0,0,0.  I don't understand where you are getting the 21 feet from.  How did you find that value?  

If the Architect wants to see the sketch points at real world elevation -- and I have no idea why he would even care -- the insert your CAD, create Topo from it and then pin it in place.  Then raise all your Levels' Elevations 6533 ft. -- or whatever.  If you have a building modeled in the Project, this could be quite problematic.  Could throw a whole bunch of errors.  

[gtdraftdesign]

After resetting the PBP to "Move to Startup Location", I was given this. See image.

[barthbradley]

If the PBP it at the Startup Location, then your Survey Point's Zero Origin is 21 ft. below it.  

[gtdraftdesign]

Here is an image of survey point. I'm feeling a little confused.

[barthbradley]

Are you using you Survey Point for anything? Got any Links or anything dependent on its location? If not, unclip it and enter 0,0,0.  Then re-clip it and move it in while clipped to the PBP (which should be at its Startup Location).  Put the SP smack dab on top of the PBP.  Now, look at or PBP coordinates.  They read 0,0,0; right?  

[gtdraftdesign]

I don't know where you're finding 0,0,0. But after moving SP to PBP I get Elev 0' 0".

[gtdraftdesign]

I meant to add an image. It's all sitting at the origin.

[barthbradley]

---

@gtdraftdesign wrote:

I don't know where you're finding 0,0,0. But after moving SP to PBP I get Elev 0' 0".

---

N/S=0

E/W=0

Elevation=0

Where did you get your SP's N/S and E/W distances from? And, PBP's Angle to True North?  

[gtdraftdesign]

The architect was trying to learn Revit after his last Revit person moved on. I'm now remembering him saying that he striped the last Revit project to start this one using the same file. I think the solution for me is to ctrl z back to the point where I can just drop the 3d topo 21' lower. That should put it in the correct location.

[gtdraftdesign · Accepted solution]

Fresh start this morning. After processing what you wrote, I reset the SP an PBP back to 0,0,0 and dragged the PBP into the SP while they were clipped and now everything is back to normal. The points elevations are now reading correctly. I learned that is how to reset the point of origin. Thank you for your help. I really appreciate the time you took to explain it to me.

[barthbradley]

---

@gtdraftdesign wrote:

Thank you for your help. I really appreciate the time you took to explain it to me.

---

Your welcome. How about thanking me with a lil' green mark?