Am I correct in thinking that if you use the AutoCAD COPY command with a surface it is no longer dynamically linked to it's originating surface but if you Create a new surface and use Edit > Paste then it is??
As an example, suppose I had a proposed surface with areas for landscaping, road, paving etc each of which was a different thickness and I want to obtain a formation level surface by reducing each of the areas by the construction thickness, what would be the best way to go about it??
Thanks
neilyj (No connection with Autodesk other than using the products in the real world)
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Yes pasting maintains a link, copy will not
Hi,
Did you ever figure out the best way to do this? I'm having the same problem, where I have a site where different areas have different construction thicknesses. I have built up a Civils 3D model which has the finished levels, which is fine for contouring etc but for my cut/ / fill volumes I want to take account of the construction thicknesses.
Any ideas?
Thanks
To save me typing, check out http://ericchappell.blogspot.co.uk/2012/01/magical-way-to-calculate-volumes.html and post back if you have further queries.
there is a bit of work to set up the "thickness" model but as long as the planietric positions of roads/buildins etc etc don't change the model will dynamically react to finished level adjustments and construction thicknesses (after a manual adjustment has been made)
neilyj (No connection with Autodesk other than using the products in the real world)
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That's a kinda neat method on that blog there. But wouldn't it be easier to just keep all your areas seperate?
I use feature lines at FG, build a surface, copy surface, lower the copy by however much you need for that area. Keep all your areas seperate. This is still dynamic: you edit the feature line and the FG surface rebuilds to FG elevations, the subgrade surface rebuilds too, and it remembers how much lower than the feature line it is supposed to be.
Mark Green
Working on Civil 3D in Canada
I suppose much will depend on whether you receive a "dumb" dwg from an architect (e.g.2D polys) or if you create your own FG from scratch using the C3D tools and also the complexity of the FG i.e. number of different construction thicknesses etc.
At the end of the day, go with whatever is easiest in your situation
neilyj (No connection with Autodesk other than using the products in the real world)
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Why create a separate surface for each material, then paste them together? Why not just build one "Material Depths" surface from all the polylines?
I also suggest that a similar approach will work for removing existing topsoil from the original ground surface. Often we need to remove different depths for different areas as shown by the geotech report.
Mark Green
Working on Civil 3D in Canada
Hi @Joe-Bouza and @neilyj666,
I know this is an old post and newer versions of C3D have made it easier to obtain the desired result of the OP. However, I just want to clarify something to be sure I'm understanding the limits of pasting surfaces.
- I have Surface A
- I paste Surface A into Surface B. All breaklines are copied from A to B and I currently have two identical surfaces and sets of breaklines.
- I use relative featurelines to adjust Surface B for varying construction material thicknesses across the surface.
- I then change the xy positions of the featurelines/breaklines in Surface A
Do the featurelines/breaklines of Surface B update to match the new location of the featurelines/breaklines in Surface A?
If not, is there a workflow that would accomplish this type of dynamic link?
Cheers,
C3D2018, Windows 10
NO. the definition of A is pasted to B. the breaklines remain original an are only controlled by edits to surface A. No duplicating of break lines occur.
Think of it as an XREF for surfaces... changes to file A show in file B. If you start adding geometry to file B, it has no connection to A other than the overlaid reference
What exactly are you trying to build that will be dynamic?
Hi @Joe-Bouza ,
Thanks for clearing that up. I'm trying to accomplish the same as the above people in this thread - a subgrade surface from a finished ground level surface.
I have a FG surface (A) defined by featurelines etc. I need a subgrade surface (B) which has different construction material thicknesses throughout the site, road, landsape, footpath etc. you know the drill. I want Surface B to be dynamically linked to A so that changes in xy, and in z to Surface A breaklines are carried over to B automatically, but surface B's featureline z-values are relative to surface A, xy-values are the identical in both surfaces.
I have done this using Eric Chappel's DDTS method which is a little cumbersome and I feel is now outdated.
What I recently tried was creating surface B using relative featurelines by copying all of the featurelines from A into B and making them relative to surface A, setting the relative difference to correspond with each material thickness. However, as you mentioned, I now have a separate set of breaklines that aren't linked to surface A in any way.
What I'm after is something that allows me to paste surface A into B. Surface B would reference the featurelines similar to a Data Reference or Xref of Surface A but all referenced featurelines in B would get their z values from "relative to surface" of A. Therefore, changes to xyz coordinates of featurelines in A would be updated in Surface B similar to an xref/data reference but the z values of featurelines in B would be relative to A....
Hope that makes sense.
Thank you in advance.
Ollie
neilyj (No connection with Autodesk other than using the products in the real world)
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I used to think the DDS idea was a good solution for getting subgrade volumes for grading. However after trying it a few times I came to realize it requires tripling the number of FG surface models (or is it quadruple?). On a small site that is not a big deal but when you get into larger sites it becomes a problem. We could use a better solution for getting subgrade volumes, no?.
Hi @neilyj666 ,
Thanks for posting. What I was suggesting wouldn't include a new set of featurelines. The second surface would reference the FL's of the original surface and link the PI/EP's z-values using the "relative to surface" function.
Although, I see your point with the common boundary lines. However, if using the DDTS method you also have to manually offset your breaklines to eliminate the same issue. Secondly, there is often already a horizontally offset featureline at the interface of two materials, obviously not always but ie: kerb upstand surrounding a parking area, or a building slab FFL above the surrounding landscaped material. In those cases, now additional FL's or manual edits other than selecting "relative to surface" and setting the relative difference amount would be required.
I'm sure my proposed method is not perfect but I'm with @Neilw_05 in that there has to be a more efficient solution than the DDTS method for such a common surface type.
@Neilw_05 yes we definitely need a better method but I doubt that will be high on Autodesk's priority as it is something that many people will actually use and it isn't anything Cloud/BIM360 related...!!!
I'm intrigued by "...tripling the number of FG surface models (or is it quadruple?)...." can you explain this??
Neil
neilyj (No connection with Autodesk other than using the products in the real world)
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Maybe it is more like triple if you don't consider the depth surface. You have your FG surface. Then you have to make a depth to subgrade surface using polygons with elevation = depth to subgrade. Then you make a volume surface to get the subgrade surface: Fg-depth=subgrade. That is 3 surfaces. Now to Calc earthwork you create a volume surface: subgrade-EG. However you can't use the subgrade surface to Calc earthwork since it is a volume surface. So you have to create a new tin surface and paste it in. So now total of 4 surface to get earthwork. All those surfaces add up to a lot of processing for a large site.
I concur that the addition work for the formation surface can be tedious and on a larger project can be a budget item unto itself ,
The rest is data management and only a few clicks for a small job or large. I am not disputing that it can be onerous to manage. to keep my sanity I try to keep as many surface separate as I can an DS to a calculation file
Keep in mind every time you change the FG surface you have to process it 4 times to get earthwork.
Update FG=1x
Update subgrade vol=1x
Update subgrade TIN=1x
Update earthwork=1x
But when Surface A changes in response to the FL change, Surface B will change in response to the Surface A change.
I use pasted surfaces frequently for this purpose. I'll generate a "composite" surface representing the final grade after all construction. This composite surface typically will have a Corridor surface for the roadway and a surface created from featurelines for the parking lot. Sometimes additional surfaces as well.
If the corridor surface changes the composite is updated to match. If the parking lot changes the composite updates.
Don Ireland
Engineering Design Technician
No,. I think you may be misunderstanding the idea of the DDTS.
the formation surface defines the structural depth as a positive number the Volume of Formation vs FG is then dynamic to any grade change .which in turn is dynamic to the SG surface that has the pasted volume surface in it
the only time you would be compelled to redo the formation is if the geometric layout changes and in that case only the formation has to change the rest is completely dynamic
hence the name Dynamic Differential Tin Surface
I do understand Joe. What I was saying is there are 4 surfaces that have to rebuild whenever a change is made. Likely you would not have Auto-rebuild on when working in this scenario so you would have to step through the rebuilds manually. We all know how fun it is to rebuild large surfaces.