How to make a stepped surface ?

[x_pro_10]

Hello there,

I am a civil Engineer. I have surveying data for the topography of the project that I work in.

I created a surface in Civil 3d by importing the points from a CSV excel file.

I named my new surface as NGL (Natural Ground Level)

Now I want to calculate the volumes of the required excavation.

We have many retaining walls on our site,because the terrain is very rigid, and hence the excavated surface will look like "Steps".

I would like to create a new surface represents the excavated topography in order then to compare the two surfaces and analyze the total cut/fill volumes of the project.

I've been trying to make stepped topography with a 90 degree angle, no slopes nor grading, but I failed !

Can anyone tell me please how to accomplish this ?!

Thanks in forward.

My Regards.

[Joe-Bouza]

Not quite enough information :
Did you create a separate surface?
Did you add break line data to represent the steps?
Is that data in the form of feature lines or 3dpoly lines,

[autoMick]

You will have trouble creating a Civil3d surface which has 90 degree steps - as Civil3d is in fact Civil2.5D and cannot handle true 3D surfaces.

You will either need to relax a bit on the 90 degrees (i.e. make it 90.1 degrees) and then use Civil3d to create a volume surface which compares the EG and stepped surfaces (this is simpler and will be close enough for volumes). or - if you really want 90 degrees then:

1. Convert the TIN to a 3D solid

2. Create your stepped surface as a 3D solid (i.e. using the 3D workspace and modelling tools)

3. Intersect the 2 solids to create the 3D volume you are after

4. use MASSPROP to report the volume of that solid.

Cheers

- Mick

[x_pro_10]

what I did is:

1) Defined my first surface from a point file, then I called it (NGL)

2) I set my perspective on the Top view to see the natural Topography of the land.

3) I imported the AutoCAD plan which shows the project components, such as buildings, retaining walls, and parking lots, etc ...

4) I traced the excavation works for the whole project as polylines and assigned certain elevations polygons that define an excavated level.

What I need is to define the new surface, which shows the final excavated (man-made) topography, in order to compare the original one with it, to find the total cut/fill volumes for the whole project's site.

Note: For example, in Sketchup you can represent the topography, and then you draw any shape, after that you can extrude the shape for a certain chosen elevation. Can I do the same for surfaces in Civil 3D ?

Thank you !

[x_pro_10]

Thanks Mick,
Actually I thought to do the same, to model my surface to the final shape that I want, then to compare it with the original one.

But since I am a bit new to Civil 3D, do you know any source (video or article) that shows the steps of doing all that modeling procedure ?
I might give this a try.

Regards

[Pointdump]

X,

Here's a really good Autodesk University video (1:24:00-Put on a pot of coffee) by Eric Chappell. He says up front that "Grading cannot be captured in a step-by-step process...", so he gives lots of examples:
http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2012/autocad-civil-3d/ten-practical...

You can also search Autodesk University for more on grading:
http://au.autodesk.com/au-online/classes-on-demand/search?full-text=&productName=AutoCAD+Civil+3D&vi...

Dave

[autoMick]

Ahh... sketchup - a favourite of mine.

Yes you can do all the sketchup things - such as extrude shapes, intersect them etc. This is the functionality I was referring to with the 3D modelling.

For most civil projects though you will find that the civil3d surface functionality is flexible enough to compare surfaces, calculate volumes, etc.

Watch those tutorials that Dave pointed out. If you do a hand drawn sketch of what you're trying to achieve then myself or someone else is bound to do a custom video for you to show you the steps.

Cheers

- Mick

[doni49]

---

@x_pro_10 wrote:

what I did is:

1) Defined my first surface from a point file, then I called it (NGL)

2) I set my perspective on the Top view to see the natural Topography of the land.

3) I imported the AutoCAD plan which shows the project components, such as buildings, retaining walls, and parking lots, etc ...

4) I traced the excavation works for the whole project as polylines and assigned certain elevations polygons that define an excavated level.

What I need is to define the new surface, which shows the final excavated (man-made) topography, in order to compare the original one with it, to find the total cut/fill volumes for the whole project's site.

Note: For example, in Sketchup you can represent the topography, and then you draw any shape, after that you can extrude the shape for a certain chosen elevation. Can I do the same for surfaces in Civil 3D ?

Thank you !

---

In C3D, you can set your surface to show specific contours (user contours) such as 593.50.  Then you can extract your user contours from the surface.  This'll give you polylines for the contours at the specified elevation(s).

[doni49]

---

@x_pro_10 wrote:

what I did is:

1) Defined my first surface from a point file, then I called it (NGL)

2) I set my perspective on the Top view to see the natural Topography of the land.

3) I imported the AutoCAD plan which shows the project components, such as buildings, retaining walls, and parking lots, etc ...

4) I traced the excavation works for the whole project as polylines and assigned certain elevations polygons that define an excavated level.

What I need is to define the new surface, which shows the final excavated (man-made) topography, in order to compare the original one with it, to find the total cut/fill volumes for the whole project's site.

Note: For example, in Sketchup you can represent the topography, and then you draw any shape, after that you can extrude the shape for a certain chosen elevation. Can I do the same for surfaces in Civil 3D ?

Thank you !

---

In C3D, you can set your surface to show specific contours (user contours) such as 593.50.  Then you can extract your user contours from the surface.  This'll give you polylines for the contours at the specified elevation(s).

[x_pro_10]

Thanks Dave, I will check them.
Good Information to know

[x_pro_10]

I have drawn 2 polygons and assigned elevations for them then I defined a surface for each one.
I also compared each one with the NGL surface.
But what I want is to connect the two surfaces together in one surface that shows the difference between the two levels and then compare this one surface to the NGL.

Do you know how to accomplish this ?

Thanks Doni

[x_pro_10]

A video will make life easier ... if possible ^_^

What I think to do is something looks like what is attached in pictures

My Best Regards

[autoMick]

It helps that you've thrown in the pictures.

As I said before the vertical faces of the steps present a problem, so you either have to define faces that are just slightly less than vertical - so you can use 3 civil3d TIN surfaces (NGL, NewSurface, volume surface) or you use the 3D modelling tools as per my initial post.

The inaccuracies associated with off-vertical faces would be minor - so either way is acceptable.

Cheers

- Mick

[autoMick · Accepted solution]

I just did a rough screencast which shows the Civil3d way. You will see that I offset the bottom of each vertical face just slightly so that the resulting 'steps' surface only has one elevation value for any given XY location. 

When you create a volume surface, it displays the elevation difference between the two surfaces being compared, but also provides the volume if you look at the volume dashboard as shown.

Cheers

- Mick

[Pointdump]

Nicely done, Mick!

Dave

[x_pro_10]

Dear Mick,

That's a really great work actually 🙂

Thank you very much !
Well done

[autoMick]

thanks guys - as with everything civil3d there's usually a few ways to achieve a similar result.

Cheers

- Mick