Creating Lowest Surface

[cattjake]

Hello guys, I am in dire need of some help ASAP.

I will try to write this as clearly and shortly as possible.

I have two surfaces created lets call them Surface A and Surface B.

They have different eleavations in different areas, sometimes Surface A is below Surface B and other times Surface B is below surface A.

Is there a way to easily create a Surface C which is a combo of Surfaces A and B taking which ever surface is lower?

[neilyj666]

Use a triangulation volume surface

[cattjake]

Thanks for the advice, i have never done that before could you give me a quick 1,2,3 of how to?

[neilyj666]

Having reread your post am I right in thinking that it is a composite lowest surface you want in which case a volume surface may not be appropriate for you? I'm not in front of civil 3d now but will reply tomorrow unless someone else cares to chime

[cattjake]

Your understanding is correct.

I want a new surface, Surface C, which is a composite of A and B depending on which one is the lowest.

[neilyj666]

What version are you running?

[cattjake]

project is in '11 but I have '12 and can move it over i need be.

[sboon]

I can almost see how to do this using a Volume surface but I don't have time to experiment.  Here's the idea but someone else will have to work out the details:

The elevations in a Volume surface are the difference between the elevations of the Base and Comparison surfaces.  When you create a volume surface there are two factors for Cut and Fill (typically set to 1.)  These factors exaggerate the volume surface elevations to allow for shrink/swell factors.  If you set the  fill factor to zero then the volume elevations would only include the areas where the comparison was lower than the base surface.

It is possible to add data from the volume surface to an existing ground surface to create a new "adjusted" surface.  If I'm right it should be possible to add the adjustment data to the base surface, and only change the areas where it's higher than the comparison.

Maybe...

[cattjake]

When / If you figure this out please let me know.

[Neilw_05]

This isn't tested but here is what I think could work,

Create a volume surface where A is the base and B the comparison. All areas in cut are where A is less than B. Everywhere else, B is less than A. Thus if you extract the zero contours you can use them to create hide/show boundaries for surface A. Once you have A clipped to include only the cut areas, create a new composite surface by pasting B then the clipped version of A.

[sboon]

Well that didn't work.

It turns out that you can change the cut/fill factors but that doesn't change the actual TIN elevations of the volume surface.  Without any way to limit the volume surface to only a cut or a fill area my idea won't work.

[neilyj666]

If using 2012 you can extract the minimum distance between surfaces which will show you the "zero contour" although you will still need to determine which surface is higher

[Civil_Engineer_In_Irvine]

This is a very tedious process.

First off, the project I developed this for was done with surfaces that have been created from csv point files only, with no breakline or boundary information. So before I would do anything I had to go through and edit the surfaces individually to make sure the slopes tie together properly and that their was not any weird elevation differerences. A lot of **** out of u and me stuff, right up front...... If I had better survey information I belive the method described below is the most accurate.

I create a volumetric comparison between the two surfaces where "A" is the base surface and "B" is the comparison surface. This volume comparison has an elevation surface style with an elvation range set at "2". Each time I have to edit the surface properties and be sure the anlayisis range goes from a negative number to zero and then from zero to a positive number. This is basically, a two color, cut fill area map done by creating and setting an elevation surface style.

With the volume surface displayed in the elevation style, it is easier to see where surface "B" overlaps surface "A" in cut and where it overlaps surface "A" as fill. I create polyline outer and show boundaries around the areas of of cut; keeping in mind that it is my goal to eliminate the fill. Where "B" doesn't overlap "A", at all, I also create a polyline boudry. The resulting edited surface "B" (with boundries) should only have areas of cut and places where "A" and "B" do not overlap. When "B" is pasted to to surface "A" it will only be the lower portions and places where there is new surface information.

To maintiain the original surfaces it is a good idea to create a composite surface "C". This will have surface "A" pasted to it first, then suface "B"(with boundries) pasted on top of it.

At first, I tried hiding the fill portions of B, but I found this can create holes of information in the composite surface.

To create the boundries, often ,I will extract the solids from the volume surface, convert the cut solids to Regions, merge them with the Union Command, and then Explode the region, to then join all the lines back together as polylines that can be used as a cut boundary.

It would be great if there was an easier way to do this? A PasteCutSurface, or PasteFillSurface command would be fantastic. I am still trying to figure out a better way to paste the cut.....

[liam.mulcahy]

Has there been any development on this in 10 years? 

There is unsuitable soil on site so I need to replace it with engineered fill

As others have said, simply pasting the bulk surface (+ strip) atop the stripped surface will not give me the correct calculation, as I in fact need the lowest combined surface.

Min. distance between surfaces will kinda work, but is super-tedious.

The way I see it is per the image; 

Step 1: Remove uncontrolled fill by cutting to the lowest surface (CUT - poor quality material for spoil or landscape repread only)

Step 2: Place engineered fill from lowest surface to boxing level. (FILL - Good material)

Cheers, Liam

[BVNTRH]

Hi

I just found a third-party module that can do this operation:

"Step 1: Remove uncontrolled fill by cutting to the lowest surface (CUT - poor quality material for spoil or landscape repread only)"
It's called Focus CAT https://www.focus.no/en/products/focus-cat-en/
From their blurb: "Terrain planning and automatic generation of overall lowest / highest terrain."

I have been searching a long time for this and I even have used the extension a couple of years, but I've been so busy I haven't dived deep enough as often is the case with many programs I use. Just skimming the surface, pun intended. 😉

[TerryDotson]

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I just found a third-party module that can do this operation:

Another (much less expensive) option is the Multiple Surface Processor in DotSoft's C3DTools.  It lets you select any number of existing surfaces and generates the lowest, highest and other options.

[BVNTRH]

Thanks, good to know. I'll spread the word at work.