Forums >> Revit Building >> Technical Support >> Basic topology and earthworks.

Tekilla

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Joined: Wed, Jul 31, 2013
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Hello.

Our company has upgraded from the Basic suite and now we have Revit. So far I'm liking it. Really straightforward and detailed.

However, I'm trying to make a first project in it, so I started with a very small project. It's a small plot where the terrain is a little rough, some craters here and there, nothing special, there's also a construction to demolish and another one to build. Plus a simple retaining wall.

The first thing I'm trying to do is to reproduce the topology in Revit, I have the level contours in '2D' because we outsourced the service. After some time I've figured out there's no way to obtain a good toposurface in Revit because of dumb triangulation (concave contours) and there's no way to tweak the triangles, so I gave up on toposurface and I'm using 'in-place mass' instead, so far it's quite good, you can control the triangulation and it just works. I'd like to display 'level' contours (topo lines) from on it thought, I'm not sure if there's a way.

Next thing I did was to create a 'cube' and use the mass to 'cut' it, so I have a plain surface where I'm going to design the construction and a rough estimation on the volume of ground we're going to need. It seems quite accurate.

I'd like to know if it's possible to calculate the forces of the ground over a retaining wall in Revit Structure? Of course if the thing was going to be massive I'd just let the structural engineering dept. project it, but it's quite small (tallest part is <1m) and utterly simple so everything is just gong to be overestimated but I'd like to have a fancy computer-calculated representation to show.

Sorry for the long post, I posted like that instead of objective questions because I'd like to know if I'm doing it the right way as I'm teaching myself .

I know Revit is not a 'Civil' program, but I'm not talking about advanced tools, just a simple topographic representation and some rough volume estimations, any architectural package should have basic ways to do that imho.

Thanks in advance for any help.

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WWHub

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Joined: Tue, May 16, 2006
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Revit's topography works great -just don't expect the contour lines to look exactly the same as any CAD file you have.  (It doesn't have to to be correct!)  If you need exactly the same as CAD and have a CAD topography file, I suggest you link that in but use your Revit modeled site for 3D.

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Tekilla

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Thank you WWHub.

The lines doesn't need to be exactly the same, but toposurface is way off. I mean, everything 'convex' just gets bridged across and transformed into totally different concave forms. This problem was discussed a lot already. How am I going to design a plants bed there if now the location is under the ground?

Anyway. Is there a way to display topolines on in-place masses? Or maybe there's a way to convert masses into toposurfaces maintaining the triangulation. In this case, is it possible to 'cut' a mass using a toposurface?

In case of linking (i don't know if it's possible to link the file because I have the plotted stuff only) will the topolines appear and will the 3d model be precise? Also, can I use the 3d model to 'cut' masses?

Thanks in advance.

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WWHub

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If your Revit topo is "incorrect" then your input was incorrect.  I can't stress enough that the system works and using other modeling sources is a poor solution.

Your best Revit topography is created directly from the points file created by the surveyor.  ..... And every point will be exact!  Then any grading you do can be quantified correctly right out of the model.

Revit's contour lines can show in the 3D model as shown attached.

Attached Images

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Tekilla

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Hey! No, the input is not wrong! The problem is the way revit 'links' the points.

I know the contours show in the 3D view, bit I'm asking if there's a way to make them show on other objects (masses) besides toposurface.

Let's say I manage to guess some extra points and end up with a decent toposurface, is there a way to use it to 'cut' a mass? (I only need a rought estimation on the volume. Using a pencil and calculator for production is ridiculous nowadays.)

Also, any ideas about the retaining wall calcs?

Thank you.

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WWHub

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Sorry - no way to do what you want.

If the site looks wrong then maybe you didn't have enough points to adequately control it.  Your surveyor should have used more points in areas that are unique.   Obviously you never hand drew a contour line or you would understand how interpolation between points determines where the contour line passes between any two points.   Given point A at 100' and point B at 400', contour 200 crosses exactly 1/3 the distance from A to B if there are no other closer points that have a smaller differential.   

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Tekilla

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Thanks WWHub.

There's no way to do what? (display contours on masses, cut a mass using a toposurface, or calc forces on a retaining wall using Revit Structure?)

I just need to have a rough estimate of the amount of ground we are going to need. This sounds quite basic imho. If there's no way to 'cut' a mass using a toposurface, is there a way to convert a toposurface to a mass? (or vice-versa)

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Typhoon

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Sorry but you can't do that.

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I Hope and I Wish to LEARN  more, and more, and more.... REVIT

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WWHub

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As I said earlier, if you use Revit's topography correctly, you can get good estimates from graded regions.  You need to spend some time with tutorials on the subject rather than trying the approach your are trying.

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Logger

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Joined: Thu, Feb 22, 2007
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I'm not sure if I got your question right. My guess is you marked the elevation points over the survey lines.

Have you tried making a toposurface "from import"? That's what I usually use and it's very close to the original survey. If your survey file has all countour lines a zero height, you can always go to cad and move them to the right height. then just follow the instruction to get a topo from an imported file.

Like others have said, use the topo tools revit gives. There's no point in "reinventing the wheel" on this feature.

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Erik

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I get from our surveyor the XYZ text file and import that into Revitt

I then underlay the surveyor's contour plan as a chek, set the contour intervalls so match the surveyors plan and inveriable the revit contours are matching very acurate the surveyors contours

It works like a charm.  I am however looking forward to acouple of additional features, like banking

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