Existing Topography Workflow

[Mike_Sanderson]

Hi,

I am wanting some advice on the best workflow to get an accurate topography on a site with existing buildings.

The issue is the survey DWGs only have points around the perimeter of existing buildings. Therefor the Revit topography joins these points across the building at ground level. If the building has a basement this is not shown in the topography.

My question is how do you deal with this in your Revit topo? How do you form a basement into an existing topo so your new topo cut and fill volumes are correct?

My current solution is to split the surface around the perimeter of the building, then create a graded region from the site outside the building. From there I edit the topo inside the building, delete any internal points and then change the boundary points elevation to the underside of slab height.

This effectively gives me an existing building pad.

[barthbradley]

That's a legit workflow - one we've used as well as others. 

[Mike_Sanderson]

Can you suggest any other ways to do this? I am looking at all options so I can bring one solution to my team.

I have see your screencast regarding multiple phasing which is great, but that is after the existing topo has been established.

Do toposolids make this process easier? 

TBH, I looked into toposolids and found them so slow to edit so have not gone there, so am going to stay in 2023 for the foreseeable future.

[barthbradley]

If you have a choice, go with 2023 or 2025. Stay away from 2024. And in answer to your question: "do toposolids make this process easier", I'd have to say: "No".  I prefer the Toposurfaces and Building Pads, which is the tool we use most often to excavate Toposurfaces.  Sounds like you are excavating a Toposurface using Split Surface and Edit Surface to shape-edit the Split Surface.  That works too, but if you have the option, Buildings Pads are the way I'd go.   FWIW.      

[Mike_Sanderson]

Can you give me some direction regarding the building pad option. 

My issue is when using a building pad on the existing phase, the graded region does not recognize the cut in the existing topo by the building pad. The new topo takes the shape of the existing topo excluding the building pad.

Am I missing something? 

[barthbradley]

In your specific case, I wouldn't Split Surface of the existing Toposurface. I would just Edit Surface of the existing monolithic Toposurface and add, remove, and change elevation of points to make the basement excavation.  

[barthbradley]

Is Modify Sub-Elements available for your existing Toposurface? If so, Add Split Line would be mighty useful here.   

[Mike_Sanderson]

There is no split line available for toposurface.

However I think I have found a nice solution which was right in front of my eyes the whole time.

1. Split the existing toposurface to the boundary of the existing building.

2. Edit the toposurface which the building is on.

3. Add additional interior points relative to surface, right beside each boundary point.

4. Change the elevation of the interior points to the underside of the slab.

5. Then "Merge Surfaces". But here is the part I was missing, uncheck "Remove points on common edges".

[barthbradley]

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@Mike_Sanderson wrote:

There is no split line available for toposurface.

Ah! My bad. I misspoke. I was thinking of a workaround for Building Pads on Toposolids that we used. There is no Modify Sub-Elements with Toposurfaces. You are absolutely correct. Winner, winner, chicken dinner!  😉

[Mike_Sanderson]

No shape editing available for toposurface (pre 2024).

I think I am sorted now, thanks for your help.