minimum and maximum elevation in volume calculation summary

[ice_a]

Could anyone kindly please explain what do the data in the summary of volume calculation mean? In LDD, typically the minimum and maximum elevations are within the range of elevations where the volume is being analyzed. In my current vol calc summary it shows something that really makes me frown, e.g, min elev of -26.00 and max elev of 752. I have checked all the proposed elevations and the minimum is 720.

Please help. Thanks.

[Jeff_M]

Post your drawing and we will likely be able to help much quicker. 

[mathewkol]

If you've made a TIN vilume surface those elevations are the min and max elevation differences between the surfaces. You have an area of cut that is 26 (-26) and you have an area of fill that is 752.

If this does not sound correct then one or both of your comparison surfaces have errors. The 752 fill mighjt suggest to me that your EG surface has a spot in it at elevation 0.

[ice_a]

The -26 is the min elev in the surface property statistic tab. I did a small test site area that i could easily check the volume manually and was correct. The problem is even in this regular small site the surface property tab showed that min and max elev is not within the range of the elev in that specific test area. I used feature lines to define the prop grade and there are only four corners with 2 different elevations to easily calc it manually. What am i missing here? Thanks.

[ice_a]

Will do, first thing in the morning, thanks!

[ice_a]

[wfberry]

When Jeff said drawing, he meant your .dwg file.

Bill

[ice_a · Accepted solution]

courtesy of ArchD:

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TIN Volume surfaces create an average elevation between the base and the comparison surface. While the volume is correct, elevations for one of the surfaces (base or comparison) will not be. To get the proper elevations of the design surface, that information will need to be obtained from the design surface itself instead.

What you are doing is absolutely correct though. You can see that the TIN Volume surface contours vary from the design if you switch it to the same surface style as the design. The contours will not match. Even in Object Viewer, the TIN Volume surface takes on a whole new shape, making elevations different, but volumes and other things found on the analysis tab found in the TIN Volume properties dialog box accurate.

Even the elevations option of analysis tab will be accurate. This option will give you how many units from the base surface to the comparison. Drop down 2 ranges with two colors, red (0 max elev, -50 min elev) and green (0 min elev, 50 max elev), and set your surface style to show elevations, you will see a colored surface showing you what areas will be cut and what areas will be fill.

 Remember that a TIN Volume surface is a comparison between two surfaces. To find the elevations of just one surface, that should be taken from the surface itself. 

Hope this helps.

[ice_a]

oops, pardon my ignorance , how do you upload a dwg file here?

[ArchD]

Mathewk hit this on the head. More accurately than I said as well. Where I said "an average between the base and comparison surface" it's accurate to state that it's not an average, but an elevation difference between the two.

For example, where the base and comparison surfaces intersect each other, that would be elevation 0 in the TIN Volume surface, and anything being cut would show as a negitive elevation and positive to any fill.

I'm glad to have helped. 🙂

[PTMI]

Hi guys,

Pardon me if I seem to missed it, but what I want to ask is, so is it possible for me to have the TIN volume surface in absolute elevation instead of relative elevation? My client would like to see the Cut and Fill surface is its absolute elvation, so they can visualize and analyze better.

Thank you.

P.

[mathewkol]

That's just not how TIN volume surfaces work, so no. I'm wondering what you think a TIN volume surface would look like if it were absolute. It's simply the difference between the other 2 surfaces. What elevation would it be if it were absolute and how would you visualize it differently?

[sboon]

If you are trying to present the cut and fill information in relation to the original surface there are some options which may be worthwhile.  You can display a grid of cut/fill labels on your site, or you can display the volume surface with elevation bands.

[jmayo-EE]

You can move the surface in the z direction and contour labels will display the new location or you can use an expression in a label to add the elevation difference.