[Therion] Fwd: Re: How to calculate the volume of a cave

[Bill Gee]

Hi Ben -

The data file I refer to is a Compass file containing centerline and LRUD data from the cave.  It is not from either Therion or Survex.

In this case the cave is very small, only 50 meters, and there are only 14 survey stations.  Retyping it into a Compass data file did not take long.

Compass and MeshLab do very different calculations to come up with volume.  For my cave Compass gives about 2900 cubic feet and MeshLab gives over 20,000 cubic feet (about 585 cubic meters).  Compass is doing a simple calculation based on polygons and using only centerline plus LRUD.  MeshLab is a much more complex calculation based on a 3D model of triangles.  Ultimately its calculation can be traces back to centerline, LRUD, walls, passage height objects and cross sections.  Therion uses all of that to build a .lox file which, through translations, becomes the MeshLab file.

========
Bill Gee


On Saturday, January 29, 2022 3:42:33 AM CST Ben Cooper wrote:
> Hi Bill, Torsten,
> What is that file; is it a standard output file from Therion or Survex?
> Best regards
> Ben
> 
> Sent from my iPhone
> 
> > On 28 Jan 2022, at 12:57, Bill Gee <bgee at campercaver.net> wrote:
> > 
> > Ha!  Torsten, you are a magician.  Thanks!
> > 
> > That was indeed exactly how I calculated this.  I had completely forgotten about it.  Fortunately the data file still exists on my Windows virtual machine, and Compass produces the number I need to defend.  I now know how to reproduce the calculation.
> > 
> > Breathing a huge sigh of relief ...
> > 
> > ========
> > Bill Gee
> > 
> > 
> >> On Friday, January 28, 2022 6:40:00 AM CST Torsten Schnitter wrote:
> >> Hi Bill
> >> 
> >> May be you are looking for this ... !?
> >> 
> >> cheers,
> >> Torsten
> >> 
> >>> ---------- Ursprüngliche Nachricht ----------
> >>> Von: Bill Gee <bgee at campercaver.net>
> >>> An: therion at speleo.sk
> >>> Datum: 14.08.2019 23:38
> >>> Betreff: Re: [Therion] How to calculate the volume of a cave
> >>> 
> >>> 
> >>> Update:  After poking around a bit, I discovered that Compass will calculate cave volume based on centerline and LRUD data.  Doing that means I have to run a Windows computer (ugh!) and type in the survey data twice (double ugh!)  Fortunately the cave for which I need this is small.
> >>> 
> >>> Can this feature be added as a suggestion for future versions of Survex?
> >>> 
> >>> Compass does quite a few other calculations.  For example, it will calculate the volume of the bounding box.  A sample report is attached.  It is nice that the report is in both meters and feet.
> >>> 
> >>>> Hi, I am also interested on volume calculation!
> >>>> 
> >>>> Please keep me updated it!
> >>>> 
> >>>>> On 11 Aug 2019, at 22:22, Benedikt Hallinger <beni at hallinger.org> wrote:
> >>>>> 
> >>>>> It would be awesome if the compiler could derive this fron the loch model and write it to the statistics block (the one where also loop closure info and total west/east and north/south dimwnsions are returned) when compiling this, as the neccessary data should be already present?
> >>>>> 
> >>>>>> Am 09.08.2019 um 14:58 schrieb Bill Gee <bgee at campercaver.net>:
> >>>>>> 
> >>>>>> Hello everyone - 
> >>>>>> 
> >>>>>> What tools can be used to calculate the volume of a cave based on center line and LRUD data?
> >>>>>> 
> >>>>>> I found an email from Martin Sluka from about 4 years ago describing how to use Loch to export a .lox file in other formats, then run that file through CloudCompare or ParaView.  The process looks very complex to me, and besides - Loch does not run on my computers, so there is no way for me to generate an export.
> >>>>>> 
> >>>>>> As far as I can tell, Survex does not have a way to calculate volume.
> >>>>>> 
> >>>>>> Could it be done with a KML file and Google Earth?
> >>>>>> 
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> > 
> > 
> > 
> > 
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