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Find the altitude for a given volume

  • 1.  Find the altitude for a given volume

    Posted 12-02-2021 04:17
    Hi, i've got a basin of which i surveyed a volume limit perimeter and surface points inside that perimeter.

    I can easily get in Siteworks or TBC the overall volume of the basin.

    I want to get the altitude of a given volume inside my basin.

    Example ==> basin goes from Z 100m to Z 80m and it contains 1000cubic meters. If i fill the basin with 800 cubic meter of water, i want to know the Z of that water level.

    Is there any way to achieve this in TBC ? Seems like i can only find a volume inside the parent one but with a given Z (surface against elevation).

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    Gregory Fyot
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  • 2.  RE: Find the altitude for a given volume
    Best Answer

    Posted 12-02-2021 19:46
    Not directly, but you can still do it rather quickly with the Earthworks report and "Volume Breakdown" at the very bottom.
    That will give the volume of each interval slice.
    If you select to export the result into Excel.

    You can just dragselect the Volume fields until you find the desired volume sum.

    Afterwards you can still double check it with a standard volume report to this elevation.

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    Ronny Schneider
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  • 3.  RE: Find the altitude for a given volume

    Posted 12-03-2021 02:17
    Thanks @Ronny Schneider for that. This is what i did when i didnt find any other way. Not precise IMHO, more like a DIY solution, but something we can do after all.

    I remain sorry that this feature doesnt exist in TBC :(​

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    Gregory Fyot
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  • 4.  RE: Find the altitude for a given volume

    Posted 12-29-2021 06:50
    Edited by Ronny Schneider 12-29-2021 09:38
      |   view attached
    I had some time to dig into the computation via macro. I found the issue I had a while ago and also found out how to create a contour via macro.
    https://community.trimble.com/communities/community-home/digestviewer/viewthread?GroupId=415&MessageKey=307c6625-a550-4135-9212-13c7f6928b2e&CommunityKey=8a262af4-a35e-4e9a-9dd3-191cc785899a&tab=digestviewer

    If you can run macros unzip the attached ZIP into a subfolder in "C:\ProgramData\Trimble\MacroCommands" and restart TBC.
    I always just use meters as units, but I spend some time to look into unit conversion as well. It should work with whatever is set in the project settings.

    It does use the same method you've been using with the Excel spreadsheet, so use the slice value wisely. If you have a surface with lots of triangles it can take a long time until you get the result.

    I might try to tweak the code in the future. Instead of having thousands of slices computed, compute total volumes with large increments and iterate recursively with smaller increments.
    Edit: I tested the recursive Algorithm, but it is much slower. In every loop it treats the surface as unknown and needs to compute the prisms, holes etc. from scratch again.



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    Ronny Schneider
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    Attachment(s)

    zip
    SCR_BasinFindVolumeRL.zip   6 KB 1 version


  • 5.  RE: Find the altitude for a given volume

    Posted 12-29-2021 20:46
    Edited by Ronny Schneider 12-29-2021 20:51
      |   view attached
    Since the recursive algorithm was so slow and with the slicer approach I have a list with volumes I thought why not create contours at volume intervals. Might be useful for flood simulations.
    I renamed the whole macro to "VolumeContours".
    The TBC-built-in function to compute all this starts to return only total volumes if I go below a certain slice thickness, 0.0001 m / 0.000329 ft. Which is surprisingly smaller than the earthworks report can do, which starts to return totals if I go below 0.001 m.

    Keep in mind that even with 0.0001 m slices the volume on large surfaces changes too much to compute a 100% accurate result. The result/contour is created once the slice sum is >= the target or the interval.



    Sidenote:
    The earthworks report into Excel also seems to be super inefficient. On a tiny test surface with 10 triangles, 10 m height and slice thickness 0.001 m I can't even press the stop watch quickly enough with my macro, but the report into Excel takes 6 minutes for those 10000 lines. HTML report is much quicker, about 3 seconds, but wouldn't give you all the slice volume decimals.

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    Ronny Schneider
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    Attachment(s)

    zip
    SCR_VolumeContours.zip   7 KB 1 version


  • 6.  RE: Find the altitude for a given volume

    Posted 12-30-2021 09:40
    Edited by GPS User 12-30-2021 09:42


  • 7.  RE: Find the altitude for a given volume

    Posted 12-30-2021 09:44
    Edited by GPS User 12-30-2021 09:47


  • 8.  RE: Find the altitude for a given volume

    Posted 12-30-2021 09:46
    This is a typical slice volume calculation.  

    Use the "Earthworks" routine under the Surface tab, pick your comparison surfaces and select "By Elevation Interval".   Your index elevation is your lowest elevation.  For 20m I'd use 0.5m increments.


    Copy and paste the table from the report into Excel and add a cumulative volumes column.   In order to get your 800m volume elevation (altitude) scan down the chart and find where the cumulative volume is 800cm (or close).  The target elevation will be at this level.



    Hope this helps.

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    Matt Eklund
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