Surface Volumes

[trynders]

Hey all,

I need some advice.  I have and existing and proposed surface.  I need a volume of fill but only to a certain existing elevation.  The magic number is 441.35 which is the 100 yr flood.  some of the proposed surface is above that.  I need to know how much I am filling up to that elevation.  Can I do a volume analysis and have a ceiling of the proposed at my 441.35?  Any advice is appreciated.

[doni49]

1. Create a new surface.
2. Paste your FG surface into the one created in step #1.
3. Set the Step1 surface to EXCLUDE elevations above 441.35 (right click the surface>Properties>Definition>Build (expand it at the top)>Exclude elevations greater than......441.35

Instead of using the FG surface in your comparison, use Step1 surface.

[trynders]

Thanks,

That sounds like it will work, but it didn't for me.  Should I see the new surface contours adjusted after changing the build definition?  I went to the Volumes Dashboard and selected two volume surfaces.  First one with the FG and a second with the Pasted new surface with edited the "Exclude about xxx elevation".  Rebuilt the new surface.   Returned the same cut/fill volume.

Am I missing something here?  Your idea sounds great

[trynders]

one more question.  When I look at the Statistics tab of my new surface with the FG pasted into and have set to exclude elevations greater than 441.35, should the general part at the top give me the Maximum elevation of 441.35?  and not the same maximum elevation as the original FG surface?

[Joe-Bouza]

have you tried the stage storage tool?

[Dexterel]

Make a flat surface at 441.35, ensure this surface covers all your design surface.

Use minimum distance between two surfaces to generate 3D poly where design meats surface 441.35. see min.png

or edit surface style to display  user contours and set in analyst 1 counter 441.35 see define contour 441.35.png. Extract user contours. The results should be the same.

Make sure the 3D poly are closed.

Add the new created 3D poly as hide boundary to your design.

If it dose not work try uploading your dwg. It will be more reviling if I show you in your dwg how to do it.

[autoMick]

I think the solution is to:

1. create the volume surface between existing and proposed
2. do an elevation analysis with one category (the upper bound being 441.35 minus the min surface elevation)
3. create a surface legend table which has a volume column.

Is this what you need?

Cheers

- Mick

[sboon]

Paste operations ignore all of the rules in the Definition tab of the destination surface.  You get the whole TIN from the source, as is.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[trynders]

Thanks to all.  You too Dexterel.  My workaround was Dexterel's idea of creating a overall flat surface at 441.35.  Did two comparisons.  One of existing to 441.35 and one of fg to 441.35 and did some manual math (subtractions) between my two volumes.  That will work.

Thanks all for the great ideas.

[Dexterel]

Hello autoMick,
I think you are wrong, your point 2.
Elevation analyse in Volume surface refers to the difference between the two compared surfaces, NOT to actual elevations. For example an elevation of 1.00m in a volume surface means the difference between the two compared surfaces is 1 m, the elevation is irrelevant.

[fcernst]

No...You can see below how you would lose your FG surface resolution interfering with its Build.

.

[fcernst]

No he's right..You're missing his Point #3...

[fcernst]

This approach fails if there are islands in the Base surface. Here's a green rectangular slice at elevation 2673:

[autoMick]

The other approach, which is much easier to visualise exactly what you are getting is to use the 3d modelling tools:

- select and extract 3d solids from both EG and proposed surfaces

- create the plane at the critical flood height

- use the slice solid tools (or the boolean sutract) to separate the volume above the flood height

- use MASSPROP to get the volume of the remainder.

A side note with this approach is when you extract the 3d solids of the proposed , you can set the base elevation based on another surface (say the existing ground). The resulting solid will then have both the volume and absolute elevation information.

Cheers

- Mick

[autoMick]

I did a quick video to demonstrate my last post.

Unfortunately the surface I picked was pretty flat to start with, but you should get the idea.

Instead of 441.35, I picked 0.5 as my critical elevation so that it would intersect with my fill volume, but note that the elevations are real world.

Cheers

- Mick

[fcernst]

Civil 3D already has the very quick..and inherent ability to do this with a simple Elevation Analysis.

We just need Development to add a Column Property in the Elevations Table for absolute elevations when analyzing a Volume surface so that the Table output doesn't always look so confusing to everyone when analyzing the Volume surface...

Here is the Idea to vote for:

http://forums.autodesk.com/t5/autocad-civil-3d-ideas/surface-elevation-analysis-of-volume-surface/id...