Topo vs Floors vs Fill region

[vghozlan]

Hi guys, 

Coming from Archicad and still Revit novice, I'm having quite a hard time with Revit dealing with topography when the project is a bit complex in terms of levels and landscape elements. I'm trying to find the best (less worst) way of modelling ground elements. 

I'm working on a basement + landscape rework. There are several"terrasse" of topography. So far I've modelled the ground with floors. The issue is that obviously when I cut sections or go underground, I'm missing the earth fill from topo.

Typically, I'd just floors for any earth part as it allows for better control than toposurface and uses earth fill region on sections/basement plan. The problem with this method (and fill regions that can't be sent behind model elements) is that I'd need to edit the boundary and go around every single model element, like on my basement plan I'd need the fill to go around each boring pile. This is stupid work and when the piles' position change, you're up for hours of updates. 

I could try and use topography, but hey, topo can not be curved so if there are any curves in the project which I have, I'm f-ed. Also, because of all the different terraces, I'd need to create different topography for each location and then somehow have a nightmare of pads to try and have some topo under the garage ramp and so on. Seems hard to manage in this specific case. If anything moves in the project, you gotta adjust a million of things. 

One "fix" I thought of is to create a floor at survey level with an earth cut fill as a surface and play with the view range. Works quite well on the plan, but with sections, it gets more complex. Since each section is different (where it cuts, section depth) you can't really have a wall with earth-cut fill on the background. 

Am I missing something? Are there some magic tricks I'm unaware of? How would you model the ground in a case like this? 

In Archicad, we got this bad boy that allows doing very easily any sort of boolean operations. And well, we also can put 2D/annotations on the background, behind model elements. 

Looking forward to any sort of advice! 

[pedruccioli]

I don't know if i understood it all, but:

The correct approach, from what I can see here, is to have a master topography, work your way through pads, sloped pads and so on. Doing this, you will see the topography cuts at their correct height.

The same is true for construction elements, they will have priority over topography in cuts, so they will always show:

Sections will work the same way:

The only problem is when you're trying to do something underground and want a "box" inside the earth. In this case, you can only make the bottom level, and everything above it will have to be made out of floors or other workarounds.

As for boolean operations and topography as a solid mesh, it is in the Revit Roadmap, and I suggest you vote for this idea: https://forums.autodesk.com/t5/revit-ideas/solid-mesh-topography-with-boolean-operations/idi-p/67037...

Cheers.

[barthbradley]

TMI. I'm having a difficult time understanding what you are trying to achieve as well.  Can you distill down to a few short sentences what it is that you would like to do in Revit  - without mention of ArchiCAD? 

[lucdoucet_msdl]

@vghozlan 

Your frustration seems to be routed in trying to reproduce an Archicad workflow with Revit families. While you can adapt Revit floors to approximate extruded volumes, you will be working against the built-in "intelligence" and constraints of the floor family.

Another issue is the conceptual approach to modelling a landscape with hardscape elements (concrete slabs, pavers, curbs, retaining walls, etc) rather than softscape elements (more organic shaped planted surfaces with hills and valleys). I understand that an initial design will want to treat a grassed lawn as an "ideal" flat surface, which is fine for a quick sketch, but importing an existing site with a complexe topography requires different tools.

This said, I would say you have several workflows open to you:

1. Hardscape: Model the entire site with floor families that have a thickness that goes below the lowest level of your project. The cut material of the different floor families (grass, paving, sidewalks) would all be the same "earth" pattern, for different surface materials;
2. Softscape: Model the entire site with a toposurface and cut with building pads for floors below grade. If you have floors under topography or planted green roofs, see the LandarchBIM blog for a workaround. You can model retaining walls, stairs and floor families for those hardscape elements that require a more planar geometry.
   
   Topo Above Structure
   
   
3. In place geometry: Model the site as a set of extrusions, boolean cuts and joins that describe a monolithic volume. You get a series of complexe 3D volumes that you can assign different materials as in workflow A.
   
   
4. Wait for Revit 2024 for the Toposolid under development in Autodesk's AEC public Roadmap.
   
   Autodesk AEC Public Roadmaps
   
   

I agree with @barthbradley , that you also need to be more specific in the problems you are encountering for us to help you. It also helps to tell us if you are working in a conceptual or production stage of design as concept presentation documents present different challenges to producing tender documents.

Hope this helps,

-luc

P.S. The LandArchBIM Blog is also an excellent resource for approaching site modelling within Revit's capabilities.

[vghozlan]

Hi all,

Thank you for your tips. The project is still at an early stage but will be moving very quickly to construction. I'm not trying to reproduce an archicad workflow, but rather trying to understand the different workflows Revit offers to figure out which one will involve as little time as possible managing the model. 

From your comments, I think my best shot is using toposurface tool mainly, as construction elements have priority on it, and work out the rest with pads and hardscape. 

I'll give it a try today and see if I can get it to work! 

Edit: 
Based on your comments, I managed to get a decent compromise.
I created one master topo for the whole site and worked out additional height points to have the topo adjust at retaining wall height changes. Then, I used Split surface tool to split the master topo at some of the key retaining walls and adjusted the amount/height of points (cleaner).
I kept the "grass floors" I had tho, as I understand you can not attribute a surface fill to toposurface, is that right? It would just look plain white on plan drawings and I guess I could also use cover fills but since it's annotation, I'd have to change it on each view if the extent were to move. 

This Balkan Architect guy on YT was quite helpful during the process. Now I'm able to see the earth fill in sections and in the basement plan, and don't have to play around with cover fills which is great. I've used thicker earth slabs above the basement as recommended. The only issue there is that the basement roof slab has a double fall to the perimeter (can't be flat for waterproofing), so I might have to end up cover filling those ones as I can't seems to be able to cut one floor with another (the earth slab with the concrete slab).