Revit Topography created from DWG file (Civil 3d) not matching DWG file

[Anonymous]

Hi, I have imported DWG file (from Civil 3d) Into Revit 2019.2. 

I did read all the topics about location too far etc and this is not theissue.

Problem is that imported 3d DWG looks exactly the same as it looks in Civil 3d, section looks the same too, but when I create topography based on that DWG file (it only has contours and triangle mesh) in that DWG file - created topography do not match DWG file (or it is very inaccurate, it seems like it is using only contours, but not using mesh to create it?).

How can this be fixed?

Screenshots showing this issue and DWG file attached.

TA!

Ziggy

[barthbradley]

Looks pretty darn good to me. 

Are you building on all 42,292 sq. ft. ?  

[Anonymous]

Cut section as per attached and compare topo vs dwg

[barthbradley]

I don't need to cut it.  I believe you.  Revit is not great a translating near vertical cuts like that.  Revit gave you 1918 Points.  You can edit Toposurface and add more.   

[lucdoucet_msdl]

@Anonymous 

I agree with @barthbradley that Revit needs additional points to deal with the vertical break lines that curbs and retaining walls represent.

From an Autodesk University example I recall but can’t find, you can ask the civil engineer to augment the point density locally at strategic locations on their civil3d surfaces (ie with 3m of the base of the building or a 600mm swath following  the curb)

-luc

[Anonymous]

loc, so you are saying when I work in Revit with topo imported from Civil 3d, I should always have DWG file as an overlay to check if the topo was created properly and if I find areas that it wasnt - I should as Civil 3d operator to add points in this area?

What is the point of having that topo in the first place if I could use DWG file instead?

Sometimes the client request topo in Revit rather than DWG from Civil 3d, that would take hours just to check if topo matched DWG 100%?

Ziggy

[barthbradley]

Get the Point File.  

[barthbradley]

Do you know what I'm talking about? A comma-delimited file.  Revit can create a Toposurface from a Point File as well.  

[lucdoucet_msdl]

@Anonymous 

loc, so you are saying when I work in Revit with topo imported from Civil 3d, I should always have DWG file as an overlay to check if the topo was created properly and if I find areas that it wasnt - I should as Civil 3d operator to add points in this area?

---

No, I was presuming you are part of a team of consultants: architect, landscape architect and civil engineer that have to work with each other to coordinate a design. In this context, it is not unreasonable to ask the civil engineer to process his civil3d surface for any vertical features such as curbs, retaining wall  before exporting the geometry to you.

of course, If you notice any problem areas, you could ask to have more points in an update. A new BIM360 work flow with Revit 2021 addresses the linking of Civil3D surfaces rather than importing.

In answer to @barthbradley suggestions, creating the toposurface from a points file generated from a Civil3D surface will generate the same as a toposurface created from a DWG export TIN mesh from the Civil3D surface. 

If you have the Civil3D file available, post it here or send me  a PM link and I can create sample for you.

-luc

[Anonymous]

@lucdoucet_msdl file attached.

Ideally I would like to be able to do it myself, using Civil 3d, without the need of "guessing" which area could be problematic for Revit to process. Is there a way to automate that?

TA!

Ziggy

[barthbradley]

---

@Anonymous wrote:

What is the point of having that topo in the first place if I could use DWG file instead?

Ziggy

---

Okay Ziggy; I give up. What is the point of having that topo in the first place if you could use the DWG  file instead?   

[Anonymous]

@barthbradley - client wants this as topo.

[barthbradley]

Alrighty then. That settles that.  Just thought there might be an opening in there for other possible workflows you were asking about.   

Take care and good luck.  

[lucdoucet_msdl]

@Anonymous 

The file you uploaded is the "EXPORTTOAUTOCAD" version of the Civil3d file and doesn't have the original surface geometry, but that is not a problem.

Here's a 3D view in Revit to visualize the difference between your Autocad TIN surface (pink) and the Revit Toposurface (brown):

So the brown parts poking above the pink correct surface are due to the different algorithms Revit / Civil3d have. A quick solution is to use 3D contour lines rather than the TIN surface in a model that has alot of steep slopes but never vertical walls.

To get to this point:

1. In Civil3d, open your TIN dwg file.

2. Create a new surface by objects (3dfaces) 

3. Set the display features to show contours and set a contour height. Set them to a seperate layer from the TIN geometry.

4. Export to autocad using (you guessed it) EXPORTTOAUTOCAD as a new DWG file.

5. In Revit, link the exported DWG file

5. Create the toposurface by linked object and select the contour geometry layers.

The ideal solution is adding points and is a more complexe workflow but is outlined in this AU course:
https://www.autodesk.com/autodesk-university/autodesk-university/class/Cant-We-All-Just-Get-Along-Ad...

-luc

P.S. I've attached the Civil3D file and exported DWG with contours in the ZIP file.

[barthbradley]

Very nice presentation/contribution, @lucdoucet_msdl.

[Anonymous]

@lucdoucet_msdl thanks for your contribution and help, much appreciated!

Could you tell me how did you do that? I tried R19 and R21, still the same.

Your 3d looks way better than mine, and my topo is still rubbish (I followed your steps and/or used your files). I recorded 30s video (attached), could you please have a look? Perhaps I am doing something wrong!

[lucdoucet_msdl]

@Anonymous 

You are completly right, I didn't improve the toposurface significantly with the contours.

As I suspected in my first post, the solution to your site will be to add more points on both sides of the vertical features. In Civil3D, there are 3 possible workflows. 2 are manual and one requires BIM360 and Autodesk Desktop Connector.

Solution 1:  Add points along feature lines and Civil3D objects spaced out less that the smallest height you want to faithfully reproduce in Revit. For example, a 200mm curb should have additional points @<200mm. You need the original Civil3D file with civil objects.

Solution 2: Add point to the surface with the smooth surface command in Civil3D at a spacing similar to Solution 1. If you do this indescriminantly on the whole surface you will be stuck with too many points. Best to split the surface in Civil 3D around the vertical features and smooth only locally.

Solution 3: Publish a surface from Civil3D to BIM360 and link to Revit Toposurface.

I can record a screen capture this weekend of Solution 2.

-luc

[lucdoucet_msdl]

@Anonymous 

Here's a follow-up on the possible workflows:

1. I've had partial success in improving the Revit Toposurface by creating Civil3D feature lines along the top and bottom ridges of the Surfaces, but the vertical features have problems at the corner returns and for the sloped driveway (inbetween vertical / horizontal).

2. Adding points by smoothing the surface in Civil 3d created huge amount of points and the "hardness" of the edges were difficult to retain.

3. Haven't tried this for lack of access to BIM 360.

I think a combination of contour lines and points along vertical features should do the trick. More to come.

-luc

[lucdoucet_msdl]

@Anonymous 

Yep, adding the contour layer of 3D polylines from the previous tries did the job.

Here's the toposurface with Revits contour lines and 3d faces exposed:

Also attached: this project file, Rvt_2020.

-luc

[lucdoucet_msdl]

@Anonymous 

In summary, for your particular situation:

1. In Civil3D, recreate a Civil3D surface from the Autocad mesh file the civil engineer sent you on layer A.

2. Add contours to the surface display style at an interval height that will add the detail to the low sloped areas (ie street and driveway) on layer B.

3a. Add feature lines to the top and bottom ridges of highly sloped areas (ie curbs and retaining walls)

3b. Add COGO points to the features lines at a spacing interval lesser that the lowest height difference (ie curb height for curbs and wall height for walls)

3c. Create a second surface with the points created along the feature lines on layer C.

4. Export the Civil 3D to Autocad.

5. In Revit, Link the Autocad file

6. Create the toposurface with the geometry on layers A (mesh), B (polyline) and C (mesh).

7. Compare the linked mesh on layer A (disregard layer C) with the toposurface and go back to civil 3d to add points to the regions that are not detailed enough.

For futur reference, this can be done more efficiently by the civil engineers technician as described in the AU course: "Can't We All Just Get Along? Advanced Workflows Between Revit and AutoCAD Civil 3D" from the 24 to 33 minute marks. They have all the original civil  corridor, cut/fill and feature lines.

The AU Course PDF Handout has a nice workflow description of what civil should do. Just include this service in the civil engineers contractual deliverables. 

-luc